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CHEMISTRY 


GENERAL,  MEDICAL,  AND  PHARMACEUTICAL, 


INCLUDING 


THE  CHEMISTRY  OF  THE  U.  S.  PHARMACOPffilA. 

A MANUAL 


ON  THE  GENERAL  PRINCIPLES  OF  THE  SCIENCE,  AND  THEIR 
APPLICATIONS  TO  MEDICINE  AND  PHARMACY. 


BY 


JOHN  ATTFIELD,  PhD.,  F.O.S., 


PROFESSOR  OF  PRACTICAL  CHEMISTRY  TO  THE  PHARMACEUTICAL  SOCIETY  OF 


FORMERLY  DEMONSTRATOR  OF  CHEMISTRY  AT  ST.  BARTHOLOMEW’S  HOSPITAL,  LONDON; 
. HONORARY  MEMBER  OF  THE  AMERICAN  PHARMACEUTICAL  ASSOCIATION; 
HONORARY  MEMBER  OF  THE  COLLEGES  OF  PHARMACY  OF  PHILADELPHIA,  NEW  YORK, 
MASSACHUSETTS,  AND  CHICAGO  ; 

HONORARY  CORRESPONDING  MEMBER  OF  THE  SOCIETY  OF  PHARMACY  OF  PARIS  ; 
SECRETARY  OF  THE  BRITISH  PHARMACEUTICAL  CONFERENCE. 


FIFTH  EDITION. 


REVISED  FROM  THE  FOURTH  (ENGLISH)  EDITION  BY  THE  AUTHOR. 


PHILADELPHIA: 


HENRY  C . LEA. 

18Y3. 


“Bat  the  greatest  error  of  all  is,  mistaking  the  ultimate  end  of  knowledge  ; for 
some  men  covet  knowledge  out  of  a natural  curiosity  and  inquisitive  temper;  some 
to  entertain  the  mind  with  variety  and  delight ; some  for  ornament  and  reputation  ; 
some  for  victory  and  contention  ; many  for  lucre  and  a livelihood  ; and  but  few  for 
employing  the  Divine  gift  of  reason  to  the  use  and  benefit  of  mankind.  Thus  some 
appear  to  seek  in  knowledge  a couch  for  a searching  spirit ; others,  a walk  for  a 
wandering  mind  ; others,  a tower  of  state;  others,  a fort,  or  commanding  ground; 
and  others,  a shop  for  profit  or  sale,  instead  of  a storehouse  for  the  glory  of  the 
Creator  and  the  endowment  of  human  life.” — Lord  Bacon. 


Entered  according  to  the  Act  of  Congress,  in  the  year  1S73,  by 
HENRY  C.  LEA, 

in  the  Ofiice  of  the  Librarian  of  Congress.  All  rights  reserved. 


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PREFACE. 


The  short  title  on  the  back  of  a book,  and  even  the  words 
on  the  title-page,  are  generally,  and  even  necessarily,  im- 
perfect descriptions  of  the  contents,  and  hence  not  unfre- 
quently  induce  at  the  outset  misconceptions  in  the  minds 
of  readers.  The  Author  of  “Chemistiy,  General,  Medical, 
and  Pharmaceutical”  would  at  once  state,  therefore,  that 
his  sole  aim  is  to  teach  the  general  truths  of  chemistry  to 
medical  and  pharmaceutical  pupils.  Only  in  a conventional 
sense  would  he  speak  of  such  subjects  as  Medical  and  Phar- 
maceutical Chemistry;  for  the  truths  of  Chemistry  are  the 
same  for  all  students — crystalline  verities  which  cannot  be 
expanded  or  compressed  to  suit  any  class  of  workers.  The 
leading  principles  of  the  science,  however,  can  be  as  easily 
illustrated  by  or  deduced  from  those  facts  which  have  in- 
terest as  from  those  which  have  little  or  no  special  interest 
to  the  class  addressed ; and  such  a course  is  adopted  in  this 
volume. 

This  manual  is  intended,  then,  as  a systematic  exponent 
of  the  general  truths  of  Chemistry,  but  is  written  solely 
for  the  pupils,  assistants,  and  principals  engaged  in  medi- 
cine and  pharmacy.  It  will  be  found  equally  useful  as  a 
reading-book  for  gentlemen  having  no  opportunities  of 
attending  lectures  or  performing  experiments,  and  as  a 
handbook  for  college  pupils ; while  its  comprehensive  Index, 
containing  six  thousand  references,  will  fit  the  work  for 
after-consultation  in  the  course  of  business  or  professional 
practice. 

From  other  chemical  text-books  it  differs  in  three  par- 
ticulars : first,  in  the  exclusion  of  matter  relating  to  com- 
pounds which  at  present  are  only  of  interest  to  the  scien- 
tific chemist ; secondly,  in  containing  more  or  less  of  the 
chemistry  of  every  substance  recognized  officially,  or  in 

281952 


IV 


PREFACE. 


general  practice,  as  a remedial  agent;  thirdly,  in  the  para- 
graphs being  so  cast  that  the  volume  may  be  used  as  a 
guide  in  studying  the  science  experimentally. 

The  order  of  subjects  is  that  which,  in  the  author’s 
opinion,  best  meets  the  requirements  of  medical  and  phar- 
maceutical students  in  Great  Britain  and  America.  Intro- 
ductory pages  are  devoted  to  a few  leading  properties  of 
the  elements.  A review  of  the  facts  thus  unfolded  affords 
opportunity  for  stating  the  views  of  philosophers  respect- 
ing the  manner  in  which  these  elements  influence  each 
other.  The  consideration  in  detail  of  the  relations  of  the 
elementary  and  compound  radicals  follows,  synthetical 
and  analytical  bearings  being  pointed  out,  and  attention 
frequently  directed  to  connecting  or  underlying  truths  or 
general  principles.  The  chemistry  of  substances  naturally 
associated  in  vegetables  and  animals  is  next  considered. 
Practical  toxicolog}^  and  the  chemical  as  well  as  microsco- 
pical characters  of  morbid  urine,  urinary  sediments,  and 
calculi  are  then  given.  The  concluding  sections  form  a 
laboratory-guide  to  the  chemical  and  physical  study  of 
quantitative  analysis.  In  the  appendix  is  a long  table  of 
tests  for  impurities  in  medicinal  preparations — also  a short 
one  of  the  saturating-powers  of  acids  and  alkalies,  designed 
for  use  in  prescribing  and  dispensing. 

In  the  course  of  the  treatment  outlined  in  the  preceding 
paragraph,  it  will  be  observed  that  the  whole  of  the  ele- 
ments are  first  noticed  superficially  and  then  fully,  and  that 
the  chemistry  of  the  common  metallic  radicals  precedes 
that  of  the  rarer;  while  the  sections  on  the  acidulous  radi- 
cals are  similarly  divided.  The  basylous  radicals  will  be 
found  to  be  arranged  according  to  analytical  relations,  the 
common  acidulous  according  to  exchangeable  value  or 
quantivalence,  and  the  rarer  acidulous  radicals  alphabeti- 
cally. It  will  be  apparent,  also,  that  in  certain  cases  the 
same  classes  of  facts  and  principles  are  brought  three  or  four 
times  under  consideration,  the  points  of  view,  however, 
differing  according  as  interest  is  concentrated  on  physical, 
synthetical,  analytical,  or  quantitative  properties.  This 


PREFACE. 


V 


arrangement  of  matter  was  adopted  partly  from  the  belief 
that  the  separate  and  general  truths  of  chemistry  never  enter 
the  mind  in  the  order  of  any  scientific  classification  at  pre- 
sent possible.  In  the  current  state  of  chemical  knowledge, 
consistency  in  the  methodical  arrangement  even  of  elements 
can  only  be  carried  out  in  one  direction,  and  is  necessarily 
accompanied  by  inconsistencies  in  other  directions,  a result 
most  perplexing  to  learners,  and  hence  totally  subversive  of 
the  chief  advantage  of  classification.  For  this  reason  the 
writer  has  preferred  to  lead  up  to,  rather  than  follow,  sci- 
entific classification — has  -allowed  analogies  and  affinities 
to  suggest,  rather  than  be  suggested  by,  classification. 
Among  the  acidulous  radicals,  especially,  any  known  sys- 
tem of  classification  would  have  given  undue  prominence 
to  one  set  of  relations  and  undeserved  obscurity  to  others. 
Then,  by  separating  more  important  from  less  important 
matter,  instruction  is  adapted  to  the  wants  of  gentlemen 
whose  opportunities  of  studying  chemistry  vary  greatly, 
and  are  unavoidably  insufficient  to  enable  them  to  gain  a 
thorough  knowledge  of  the  science.  One  great  advantage 
of  the  mode  of  treatment  is  that  diffu^lties  of  nomen- 
clature, notation,  chemical  constitution,  and  even  those 
arising  from  conventionality  of  language,  are  explained  as 
they  arise,  instead  of  being  massed  under  the  head  of 
“Introductory  Chapters,’^  “Preliminary  Considerations,” 
or  “ General  Remarks,”  which  are  commonly  too  difficult 
to  be  understood  by  a beginner,  too  voluminous  to  be  re- 
membered except  by  the  aid  of  subsequent  lessons,  and  are 
consequently  the  cause  of  much  trouble  and  confusion. 
This  plan  has  also  admitted  of  greater  prominence  being- 
given  to  “ The  General  Principles  of  Chemical  Philosophy,” 
the  only  section  which  the  student  is  asked  frequently  to 
return  to  and  employ  in  the  interpretation  of  the  pheno- 
mena obtained  by  experiment.  An  elementary  knowledge 
of  the  subjects  of  Gravitation,  Heat,  Light,  Sound,  Elec- 
tricity, and  Magnetism  cannot  be  too  strongly  recom- 
mended to  the  student  of  Chemistiy.  The  first  portion 

I* 


VI 


PREFACE. 


of  this  Manual  would  have  been  devoted  to  an  exposition 
of  these  branches  of  Physics,  so  far  as  they  bear  on  Che- 
mistry, did  not  the  many  special  books  on  Physics  render 
such  a course  unnecessary.  Quantitative  chemical  analysis 
frequently  involving  determinations  of  temperature,  specific 
gravity,  and  atmospheric  pressure,  a few  paragraphs  on 
these  subjects  are  made  introductory  to  the  sections  on 
quantitative  operations. 

Dalton’s  hypothesis  of  the  atomic  condition  of  all  matter 
is  adopted  in  this  book,  the  author  believing  that,  in  the 
present  state  of  knowledge  and  education,  philosophic 
conceptions  regarding  chemistry  can  only  be  taught  to 
medical,  pharmaceutical,  and  the  great  majority  of  general 
students  in  some  such  objective  manner. 

The  chemical  notation  of  the  work  is  in  accordance  with 
modern  theories.  Equations  illustrative  of  pharmacopceial 
processes  have  a name  attached  to  each  formula. 

Chemical  nomenclature  has  been  modernized  to  the  ex- 
tent of  defining  the  alkali-metal  and  earthy  salts  as  those 
of  potassium,  sodium,  ammonium,  barium,  calcium,  magne- 
sium, and  aluminium,  instead  of  potash,  soda,  ammonia, 
baryta,  lime,  magnesia,  and  alumina.  The  author  con- 
fidently believes  that  this  change,  founded  on  views  now 
adopted  by  all  prominent  writers  on  chemistry,  and  used 
in  the  Pharmacopoeia  of  the  United  States,  will  be  accepted 
and  become  popular  with  pharmacists ; it  is  a step  in  the 
direction  of  simplicity  and  consistenc}^,  and  involves  far 
less  hypothesis  than  is  contained  in  the  old  system.  The 
name  nitrate  of  potash,  for  example,  was  based  on  the  pure 
assumption  that  nitre  contained  oxide  of  potassium  or 
potash  and  nitric  anhydride,  then  erroneously  termed  acid. 
By  the  modern  name  nitrate  of  potassium,  all  that  is  in- 
tended to  be  conveyed  is  that  nitre  contains  the  element 
common  to  all  potassium  compounds,  and  the  group  of 
elements  common  to  all  nitrates.  Under  the  old  method, 
students  always  experienced  difficulty  in  distinguishing 
salts  of  the  metal  from  salts  of  its  oxide — salts  of  potas- 
sium, for  instance,  from  salts  of  potash;  under  tlie  nevy 


PREFACE. 


vii 


view  no  such  difficulty  arises.  Names  such  as  potassium 
nitrate  or  potassic  nitrate  are  also  consistent  with  modern 
views,  but  for  general  adoption  are  too  unlike  the  original. 
The  contractions  in  Latin  for  names  like  “ nitrate  of  potas- 
sium’^ are  identical  with  those  names  resembling  “ nitrate 
of  potash;”  an  accidental  circumstance  that  will  much 
facilitate  the  general  introduction  of  the  former  among 
medical  practitioners  and  pharmacists,  and  a practical  ad- 
vantage that  must  determine  the  choice  over  the  other 
chemically  equivalent  names  just  mentioned.  The  author 
ventures  to  express  his  extreme  gratification  at  the  adop- 
tion of  this  system  of  nomenclature  in  the  recently  pub- 
lished Pharmacopoeia  of  the  United  States  (1873). 

The  Metric  System  of  Weights  and  Measures  (that 
which,  doubtless,  is  destined  to  supersede  all  others)  is 
alone  used  in  the  sections  on  Quantitative  Analysis.  In 
other  parts  of  the  Manual  avoirdupois  weights  and  impe- 
rial measures  are  employed. 

It  is  hoped  that  the  numerous  etymological  references 
scattered  throughout  the  following  pages  will  be  found 
useful.  Words  in  Greek  have  been  rendered  in  English 
characters,  letter  for  letter.  The  word  “ official”  is  used 
throughout  for  things  recognized  officially  by  the  compilers 
of  the  Pharmacopoeia ; officinal”  in  its  original  applica- 
tion to  the  officina  or  shop. 

Students  are  strongly  recommended  to  test  their  pro- 
gress by  frequent  examination.  To  this  end  appropriate 
questions  are  appended  to  each  subject. 

The  Author’s  ideal  of  a Manual  of  Chemistry  for  medi- 
cal and  pharmaceutical  students  (one  he  is  conscious  of 
not  having  yet  realized)  is  one  in  which  the  chemistry  of 
every  substance  having  interest  for  the  followers  of  medi- 
cine and  pharmacy  is  noticed  at  more  or  less  length  in 
proportion  to  its  importance,  and  at  least  its  position  in 
relation  to  the  leading  principles  of  chemistry  set  forth 
with  all  attainable  exactness.  Such  a work  will  doubtless 
in  certain  parts  partake  of  the  character  of  a dictionary ; 
but  this  is  by  no  means  a fault,  especially  if  a good  index 


viii 


PREFACE. 


be  appended ; for  the  points  of  contact  between  pure  and 
applied  chemistry  are  thus  multiplied,  and  abundant  out- 
lets supplied,  by  which  a lover  of  the  science  may  pass  into 
other  chemical  domains  by  aid  of  other  guides,  or  even 
into  the  regions  of  original  research.  Among  the  rarer 
alkaloids,  bitter  bodies,  glucosides,  salts  of  organic  radi- 
cals, solid  fats,  fixed  oils,  volatile  oils,  resins,  oleo-resins, 
gum-resins,  balsams,  and  coloring-matters,  mentioned  in 
this  volume,  will  be  found  many  such  points  whence  the 
ardent  student  may  start  for  the  well-known  obscure  or 
untrodden  paths  of  scientifiie  chemistry. 


Within  five  years  a demand  has  arisen  for  five  editions 
of  this  Manual.  The  First  was  intended  as  a handbook  of 
practical  chemistry  for  medical  and  pharmaceutical  pupils  ; 
but  the  notes  and  remarks  made  respecting  most  of  the  ex- 
periments were  found  to  be  so  useful  by  students  that  this 
portion  of  the  volume  was  in  the  Second  Edition  suffi- 
ciently extended  to  render  the  book  more  fairly  complete 
in  itself.  In  response  to  a call  from  professional  friends 
in  the  United  States  in  1870,  the  work  was  revised  by  the 
Author  for  the  followers  of  medicine  and  pharmacy  in 
America,  the  chemistry  of  the  Preparations  and  Materia 
Medica  of  the  United  States  Pharmacopoeia  being  intro- 
duced, and  such  other  adaptations  included  as  to  form  a 
Third  Edition.  A Fourth  was  presented  to  English  work- 
ers in  the  autumn  of  1872,  and  on  that  is  now  founded  this 
Fifth  Edition  for  American  students.  Each  of  the  latter 
editions  is  entirely  distinct  from  the  other ; but  both  con- 
tain such  corrections  and  additions  (altogether  about 
seventj^  P^-ges)  as  seemed  necessary  to  present  the  science 
in  its  latest  developments — also  a rewritten  chapter  on  the 
General  Principles  of  Chemical  Philosophy,  and  black- 
letter  headings  to  all  paragraphs  relating  to  Preparations 
of  the  respective  Pharmacopoeias. 

17  Bloomsbury  Square,  London, 

Mar  ell,  1873. 


APPARATUS. 


IX 


APPARATUS  FOR  EXPERIMENTS  IN  ANALYSIS. 


List  of  Apparatus  suitable  for  a three  months’  course  of  practical 
chemistry  in  the  summer  session  of  medical  schools,  or  for  any  similar 
series  of  lessons — including  the  preparation  of  elementary  gases,  ana- 
lytical reactions  of  common  metals  and  acidulous  radicals,  analysis 
of  single  salts,  chemical  toxicology,  and  the  examination  of  urine, 
urinary  sediments,  and  calculi : — 


One  dozen  test-tubes. 

Test-tube  stand. 

Test-tube  cleaning-brush. 

A few  pieces  of  glass  tubing,  8 to 
16  in.  long,  with  a few  inches  of 
India-rubber  tubing  to  fit. 

Small  flask. 

Two  small  beakers. 

Two  small  funnels. 

Two  watch-glasses. 

Two  or  three  glass  rods. 
Wash-bottle. 

Small  pestle  and  mortar. 

A 2-pint  earthenware  basin. 

( This  set,  packed  in  a deal-box, 
apparatus  maker  for  about  seven 


A 2-inch  and  a 3-inch  evap.  basin. 
Two  porcelain  crucibles. 
Blowpipe. 

Crucible  tongs. 

Bound  file. 

Triangular  file. 

Small  retort-stand. 

Sand-tray. 

Wire  triangles. 

Platinum  wire  and  foil. 
Test-paper. 

Filter-paper. 

Towel. 

Two  dozen  corks. 

can  be  obtained  of  any  chemical- 
dollars.) 


APPARATUS  FOR  EXPERIMENTS  IN  SYNTHESIS  AND  ANALYSIS. 

A larger  set,  suitable  for  the  performance  of  most  of  the  synthe- 
tical as  well  as  analytical  experiments  described  in  this  manual : — 


A set  of  evaporating-basins,  of  the 
following  sizes : — 

One  8J-inch.  One  4-inch. 

One  l^-inch.  Two  3-inch. 

One  6J-inch. 

One  retort-stand  and  three  rings. 
Two  test-glasses. 

One  half-pint  fiask. 

One  half-quire  filter-paper. 

Two  porcelain  crucibles. 

One  measure-glass,  5 oz. 
Blowpipe,  8-inch,  Black’s. 

Two  glass  funnels. 

One  doz.  test-tubes  (German  glass). 
One  test-tube  brush. 


One  pair  of  8-inch  brass  crucible- 
tongs. 

Two  soup-plates. 

One  fiat-plate. 

Two  spatula  knives. 

One  pair  of  scissors. 

One  round  file. 

One  triangular  file. 

One  half-pound  glass  rod. 

One  half-pound  glass  tubing. 

One  ft.  small  India-rubber  tubing. 
Three  dozen  corks  of  various  sizes. 
Platinum  wire  and  foil. 
Test-papers. 

A nest  of  three  beakers. 


[This  set,  packed  in  a case,  can  be  obtained  of  any  chemical- 
apparatus  maker  for  about  twelve  dollars.) 

A sponge,  towels,  and  note-book  may  be  included. 


X 


APPARATUS  AND  REAGENTS. 


FURNITURE  OF  A LABORATORY. 

The  following  apparatus  should  be  ready  to  the  hand  of  students 
following  an  extended  course  of  practical  chemistry,  in  a room  set 
apart  for  the  purpose  : — 


A bench  or  table  and  stool. 

Water-supply  and  waste-pipe. 

A cupboard  attached  to  a chim- 
ney with  an  outward  draught. 

A furnace  fed  with  coke ; tongs, 
hot-plate,  or  sand-bath,  etc. 

A waste-box. 

Shelves  for  chemicals  and  other 
materials  in  jars  or  bottles. 

Gas-supply  and  lamp  with  flexible 
tube  (or  a spirit  lamp  and  spirit). 


Test-tube  rack,  two  dozen  holes. 
Iron  stand  or  cylinder  for  sup- 
porting large  dishes. 

Iron  adaptors  for  fitting  dishes  to 
cylinder. 

Pestle  and  mortar,  5 or  6 inches. 
One  6-inch  funnel. 

Brown  pan,  1 or  2-gallon. 

White  jug,  1-gallon. 
Water-bottle,  quart. 

Twenty-eight  test-bottles,  6-oz. 


Other  articles,  such  as  flasks,  retorts,  receivers,  condensers,  large 
evaporating-dishes,  may  be  obtained  as  wanted.  In  Quantitative 
Analysis  the  apparatus  described  in  the  sections  on  that  subject  will 
be  required. 


REAGENTS. 


Certain  chemicals  are  used  so  frequently  in  analytical  processes 
that  it  is  desirable  to  have  small  quantities  placed  in  bottles  in  front 
of  the  operator.  As  these  reagents  or  “tests’"  are  generally  em- 
ployed in  a state  of  solution,  nearly  all  the  solid  salts  may  at  once 
iDe  dissolved  (in  distilled  water).  The  bottles  employed  should  be 
well  stoppered,  and  of  5 or  6 ounces  capacity.  The  bottles  should 
not  be  more  than  three-quarters  full ; single  drops,  if  required,  can 
then  be  poured  out  with  ease  and  precision.  The  following  list  of 
test  solutions  is  recommended;  directions  for  methods  of  preparing 
those  not  readily  purchasable  will  be  found  by  referring  to  the 
Index : — 


Sulphuric  Acid,  strong. 
Nitric.  Acid,  strong. 
Hydrochloric  Acid,  strong. 
Acetic  Acid,  strong. 


Sol.  of  Potash,  5 per  cent,  or  B.P. 
“ Soda,  5 to  15  per  cent. 

“ Ammon.  10  per  cent,  or  B.P. 
Lime-water,  saturated. 


The  next  nine  may  contain  about  10  per  cent,  of  solid  salt : — 


Carbonate  of  Ammonium,  with  a 
little  solution  of  Ammonia 
added. 

Chloride  of  Ammonium. 

Phosphate  or  Arseniate  of  Am- 
monium. 


Sulphydrate  of  Ammonium. 
Chloride  of  Barium. 
Chloride  of  Calcium. 
Phosphate  of  Sodium. 
Neutral  Chromate. 


CHEMICALS. 


XI 


The  succeeding  seven  may  have  a strength  of  about  5 per  cent. : — 


Ferrocyanide  of  Patassium. 
Ferridcyanide  of  Potassium. 
Iodide  of  Potassium. 
Oxalate  of  Ammonium. 


Perchloride  of  Iron. 
Nitrate  of  Silver. 
Perchloride  of  Platinum. 


LISTS  OF  CHEMICALS. 


List  of  chemicals  necessary  for  the  practical  study  of  the  non- 
metallic  elements  mentioned  on  pp.  13  to  28.  The  quantities  are 
sufficient  for  several  experiments. 


Chlorate  of  Potassium  . . I oz. 

Black  Oxide  of  Manganese  1 oz. 

Zinc 1 oz. 

Oil  of  Yitriol 2 oz. 


Phosphorus  . . 

Hydrochloric  Acid 
Sulphur  .... 
Iodine  .... 


2 oz. 
1 oz. 
i oz. 
i oz. 


List  of  chemicals  necessary  for  the  analytical  study  of  the  metal- 
lic and  acidulous  radicals  (pages  51  to  310).  The  quantities  will 
depend  on  the  frequency  with  which  experiments  are  repeated  or 
analysis  performed ; those  mentioned  are  sufficient  for  one  or  two 
students.  The  articles  are  given  in  the  order  in  which  they  will  be 
required.  The  eight  substances  mentioned  in  the  above  list  are 
included. 


The  set  of  test  solutions 

Bicarbonate  of  Potassium 

1 oz. 

described  on  the  pre- 

Acetate of  Lead  .... 

1 oz. 

vious  page. 

Cyanide  of  Potassium  . . 

i oz. 

Carbonate  of  Potassium 

1 

OZ. 

Hyposulphite  of  Sodium 

1 oz. 

Tartaric  Acid 

1 

oz. 

A Lithium  salt  ...  10  grs. 

Litmus 

1 

4 

oz. 

Nitrate  of  Strontium  . . 

i oz. 

Sulphate  of  Magnesium  . . 

1 

oz. 

Black  Oxide  of  Manganese 

i\h. 

Sulphate  of  Zinc  .... 

1 

oz. 

Chloride  of  Manganese  . . 

i oz. 

Alum • . 

1 

oz. 

Chloride  of  Cobalt  . . 50  grs. 

Sulphide  of  Iron  .... 

1 

lb. 

Nitrate  of  Nickel  . . . 

i oz. 

Oak-galls 

1 

oz. 

Chloride  of  Chromium  . . 

i oz. 

Sulphocyanate  of  Potassium 

1 

4 

oz. 

Gold  leaves 2 

or  3. 

White  Arsenic  .... 

i 

oz. 

Chloride  of  Cadmium  . . 

i oz. 

Zinc 

1 

2 

lb. 

Nitrate  of  Bismuth  . . . 

i oz. 

Charcoal  . . . . . . 

1 

lb. 

Bromide  of  Potassium  . . 

i oz. 

Sulphate  of  Iron  . . i . 

1 

oz. 

Starch  

1 oz. 

Copper  Foil 

1 

oz. 

Nitrate  of  Potassium  . . 

1 oz. 

Sulphate  of  Copper  . . . 

1 

oz. 

Copper  borings  or  turnings 

l.oz. 

Tartar  Emetic  .... 

1 

2 

oz. 

Indigo 

i oz. 

Mercury 

1 

oz. 

Chlorate  of  Potassium  . . 

1 oz. 

Corrosive  Sublimate  . . . 

i 

oz. 

Iodine 

i oz. 

Calomel  ....... 

X 

oz. 

Spirit  of  Wine  .... 

1 oz. 

Tin 

1 

oz. 

Sulphur 

1 oz. 

xii 


CHEMICALS. 


Acid  Oxalate  of  Potassium  1 oz. 


Citric  Acid 1 oz. 

Phosphorus 1 oz. 

Borax 1 oz. 

Turmeric 1 oz. 


Benzoic  Acid  . 
Pluor  Spar  . . 

Tannic  Acid 
Gallic  Acid 
Pyrogallic  Acid 


. . 50  grs. 

. . . 1 oz. 

. . 50  grs. 

. . 50  grs. 

. . 50  grs. 


The  quantities  of  materials  required  for  the  study  of  chemistry 
synthetically  will  necessarily  vary  with  the  desires  and  tastes  of 
the  operator,  or  according  to  the  number  and  requirements  of  stu- 
dents working  together. 


CONTENTS. 


PAGE 

Preface iii 

Apparatus . . . ix 

Reagents  x 

Lists  of  Chemicals • . . . xi 

Introduction 13 


General  Properties  of  the  ^s'  on-Metallic  Elements  1 5 
Symbols  and  Derivation  of  Names  qf  Elements  . 28 

The  General  Principles  of  Chemical  Philosophy  . 32 

Common  Metallic  Elements,  their  Official  Pre- 
parations, AND  Tests  : — 

Salts  of  Potassium,  Sodium,  Ammonium,  Barium, 
Calcium,  Magnesium,  Zinc,  Aluminium,  Iron, 
Arsenicum,  Antimony,  Copper,  Mercury,  Lead, 

Silver 52 

Analytical  Charts,  for  Ordinary  Metals  . . . 197 

Rarer  Metallic  Elements,  their  Official  Prepara- 
tions, AND  Tests  : — 

Salts  of  Lithium,  Strontium,  Manganese,  Cobalt, 
Nickel,  Chromium,  Tin,  Gold,  Platinum,  Cad- 


mium, Bismuth . 200 

Analytical  Charts,  for  all  Metals 229 


Common  Acidulous  Radicals,  Official  Acids,  and 
Tests  : — 

Chlorides,  Bromides,  Iodides,  Cyanides,  Nitrates, 
Chlorates,  Acetates,  Sulphides,  Sulphites, 
Sulphates,  Carbonates,  Oxalates,  Tartrates, 

Citrates,  Phosphates,  Borates 

2 


235 


XIV 


CONTENTS. 


PAGE 

Salts  of  Rarer  Acidulous  Radicals  : — 

Benzoates,  Cyanates,  Formates,  Hippurates,  Fer- 

ROCYANIDES,  FeRRIDCYANIDES,  FlUORIDES,  HyPO- 
PHOSPHITES,  Hyposulphites,  Lactates,  Malates, 
Meconates,  Metaphosphates,  [N'itrites,  Phos- 
phites, Pyrophosphates,  Silicates,  Sulphocy- 
anates,  T annates,  Gallates,  Urates,  Yaleri- 


ANATES 298 

Analytical  Chart  for  Acidulous  Radicals  . . . 326 

Sy^stematic  Analy'sis  328 


Alkaloids,  Amylaceous  and  Saccharine  Sub- 
stances, Glucosides,  Alcohol  and  Allied 
Bodies,  Albumenoid  and  Gelatigenous  Sub- 
stances, Pepsine,  Fatty  Bodies,  Resinoid  Sub- 


stances, Coloring-matters 338 

Toxicology 418 

Examination  of  Morbid  Urine  and  Calculi  . . . 429 

Official  Galenical  Preparations 442 

Official  Chemical  Preparations 444 

Quantitative  Analysis  : — 

Introductory  Remarks 445 

Measurement  of  Temperature 441 

Estimation  of  Weight 452 

Weights  and  Measures 453 

Specific  Gravity 463 

Correction  of  the  Yolume  of  Gases  for  Pres- 
sure AND  Temperature 469 

Yolumetric  Analysis 475 

Gravimetric  Analysis 497 

Dialysis  . 537 


CONTENTS. 


XV 


PAGE 

Appendix: — 

Table  of  Official  Tests  for  Impurities  in  Pre- 
parations OF  THE  British  Pharmacopceia  . . 541 


Saturation  Tables 549 

The  Elements,  their  Symbols  and  Atomic 

Weights 551 

Index 553 


CHEMISTEY: 

GENERAL,  MEDICAL,  AND  PHARMACEUTICAL. 


INTRODUCTION.* 

The  infinite  variety  of  solid,  liquid,  and  gaseous  sub- 
stances of  which  our  earth  and  atmosphere  are  composed, 
may  be  resolved  with  more  or  less  difficulty  into  sixt}- 
three  distinct  forms  of  matter.  These  are  appropriately 
termed  Elements,  for  by  no  known  means  can  they  be  fur- 
ther decomposed  or  subdivided.  Only  a few  (such  as  gold) 
occur  naturally  in  the  uncombined  state,  but  the  greater 
number  are  combined  in  so  subtle  a manner  as  to  conceal 
them  from  ordinary  methods  of  observation.  Thus  none 
of  the  common  properties  of  water  indicate  that  it  is  com- 
posed of  two  elements,  both  gases,  but  differing  much  from 
each  other : nor  can  the  senses  of  sight,  touch,  and  taste, 
or  other  common  means  of  examination,  detect  in  their 
concealment  the  three  elements  of  which  sugar  is  com- 
posed. The  art  by  which  these  and  all  other  compound 
substances  are  resolved  into  their  elements,  is  termed 
Chemistry,  derived  possibly  from  the  Arabic  word  kamai^ 
to  conceal,  whence  al  kimia^  or  alchemy,  an  art  which  at  the 
time  the  name  alchemy  was  given  had  but  little  more  for 
its  object  than  the  transmutation  of  the  baser  metals  into 
gold.  The  art  of  chemistry  also  includes  the  construc- 
tion of  compounds  from  elements,  and  the  conversion  of 
substances  of  one  character  into  those  of  another.  The 
general  principles  or  leading  truths  relating  to  the  elements, 
to  the  manner  in  which  they  severally  combine,  and  to  the 
properties  of  the  compound  substances  formed  by  their 
union,  constitute  the  science  of  chemistry.*}* 

* Students  using  this  book  as  a guide  in  following  chemistry  prac- 
tically should  read  the  first  three  pages,  and  then  commence  work  by 
preparing  oxygen. 

t Persons  who  practise  the  art  and  science  of  Chemistry  are  known 
as  Chemists,  though  conventionally  the  latter  name  includes  those 
2 


14 


NON  - METALLIC  ELEMENTS. 


From  these  few  words  concerning  the  nature  of  the  art 
and  science  of  chemistr3",  it  will  be  seen  that  in  most  of  the 
occupations  that  engage  tlie  attention  of  man  chemistry 
plays  an  important  part — in  few  more  so  than  in  the  prac- 
tice of  Therapeutics*  and  Pharmac3\f 

Air,  water,  food,  drugs,  and  chemicals,  in  short  all  ma- 
terial substances,  are  composed  of  a few  elements.  An 
intimate  knowledge^of  the  properties  of  these,  and  of  the 
various  substances  the3"form  by  combining  with  each  other, 
a knowledge  of  the  power  or  force  (the  chemical  force,  or 
chemical  affinit3^)  by  which  the  elements  contained  in  those 
compounds  are  held  together,  and  an  application  of  such 
knowledge  to  Pharmac3’  and  Medicine,  must  be  the  objects 
sought  to  be  attained  by  the  learner,  for  whom  this  work 
has  been  especially  written. 


The  Elements. — Of  the  sixt3^-three  known  elements  thirt3^- 
nine  are  of  medical  or  pharmaceutical  interest ; of  these, 
about  two-thirds  are  metals,  and  one-third  non-metals:  the 
remainder  are  so  seldom  met  with  in  nature  as  to  have 
received  no  practical  application  either  in  medicine,  art,  or 

who  simply  deal  in  chemicals.  Hence  have  risen  the  distinguishing 
appellations  of  Analytical,  Pharmaceutical,  and  Manufacturing  Che- 
mists. The  compounder  of  medicine  is  by  common  consent  a chemist 
only  because  he  is  constantly  engaged  in  operations  with  chemical 
substances  used  as  remedial  agents,  his  moral  right  to  the  name 
depending  on  the  amount  oL chemical  knowledge  he  possesses  con- 
cerning those  substances.  If  he  keep  an  open  shop,  lie  is  in  Great 
Britain  known  as  a Chemist  and  Druggist^  his  higher  title  being  Phar- 
maceutical Chemist ; these  respective  designations  he  legally  assumes 
on  passing  the  Minor  and  Major  Examinations,  conducted  by  the 
Pharmaceutical  Society  of  Great  Britain  in  accordance  with  the  pro- 
visions of  the  Pharmacy  Acts  of  1852  and  18(18.  These  classes  are 
frequently  spoken  of  collectively  as  Pharmaceutists,  a term  also  used 
in  the  United  States. 

* Therapeutics  (0epa7r£uT(xo?,  therapeutikos,  from  Bepamviu,  therapeuo, 
to  nurse,  serve,  or  cure)  is  that  branch  of  medicine  which  treats  of 
the  application  of  remedies  for  diseases  ; it  includes  dietetics.  The 
therapeutist  also  takes  cognizance  of  hygiene,  that  department  of  me- 
dicine which  respects  the  preservation  of  health. 

f Pharmacy  (from  ipap/txctKov,  pharmakon,  a drug)  is  the  generic 
name  for  the  operations  of  preparing  or  compounding  medicines, 
whether  performed  by  the  Medical  Practitioner  or  by  the  Chemist  and 
Druggist.  It  is  also  sometimes  applied,  like  the  corresponding  term 
^Surgery,’  to  the  apartment  in  which  the  operations  are  conducted. 


OXYGEN. 


15 


manufacture.  Before  intimately  studying  the  elements, 
it  is  desirable  to  acquire  some  general  notions  concerning 
them : such  a Jrrocedure  will  also  serve  to  introduce  the 
practical  student  to  his  apparatus,  and  make  him  better 
acquainted  wdtli  the  various  methods  of  manipulation.* 

Metallic  Elements. — With  regard  to  the  metallic  ele- 
ments, it  may  be  safely  assumed  thakthe  reader  has  suffi- 
cient knowledge  for  present  purposes  ; but  little,  therefore, 
need  now  be  said  respecting  them.  He  has  an  idea  of  the 
appearance,  relative  w^eight,  hardness,  etc.,  of  such  metals 
as  gold,  silver,  copper,  lead,  tin,  zinc,  and  iron.  If  he  has 
not  a similar  knowledge  of  mercury,  antimony,  arsenicum, 
platinum,  nickel,  aluminium,  magnesium,  potassium,  and 
sodium,  he  should  commence  his  studies  by  seeing  and 
handling  specimens  of  each  of  these  metals. 

Non-Metallic  Elements.’\ — With  regard  to  the  non-me- 
tallic  elements,  it  is  here  supposed  that  the  student  has  no 
general  knowledge.  He  should  commence  his  studies 
therefore  by  a series  of  operations  as  follows,  on  eight  out 
of  their  number. 


OXYGEN. 

Preparation. — As  oxygen  is  the  most  abundant  element  in  nature, 
forming,  though  in  a combined  state,  about  one-half  of  the  whole 
weight  of  our  globe,  it  may  safely  be  assumed  that  this  element  can 
readily  be  obtained  in  the  free  condition  in  a state  of  purity.  In  fact, 
the  air  itself  contains  about  one-fifth  of  its  bulk  of  oxygen,  though 
that  element  cannot  be  separated  sufficiently  easily  and  readily  for 
experimental  purposes.  It  is  preferable  to  apply  heat — that  force 
which  will  often  be  noticed  as  antagomstic,  so  to  speak,  to  chemical 
union.;  heat  generally  separating  particles  of  matter  further  from 
each  other,  while  chemical  attraction  tends  to  bind  them  closer 
together — it  is  better  to  heat  certain  compounds  containing  oxygen  ; 

* This  allusion  to  apparatus  need  not  discourage  the  youngest  pupil. 
With  the  aid  of  a few  phials,  wine-glasses,  or  other  similar  vessels 
always  at  hand,  he  may,  by  studying  the  following  pages,  learn  the 
chemical  reactions  which  are  constantly  occurring  in  the  course  of 
making  up  medicines,  understand  the  processes  by  which  medicinal 
preparations  are  manufactured,  and  detect  adulterations,  impurities, 
or  faults  of  manufacture.  Among  the  substances  used  in  medicine, 
will  be  found  nearly  all  the  chemicals  required.  If,  in  addition,  a 
dozen  test-tubes,  and  a few  feet  of  glass  tubing  be  procured,  many  of 
the  experiments  described  may  be  performed.  For  full  lists  of  ap- 
paratus and  chemicals  see  introductory  pages. 

t These  bodies  are  sometimes  termed  metalloids  (from  fXEraXXoVf 
metallon,  a metal,  and  eidos,  likeness);  but  the  name  is  not  ap- 
propriate, for  the  non-metallic  elements  have  no  likeness  to  metals. 


16 


NON-?»IETALLTC  ELEMENTS. 


the  latter  is  then  evolved  in  its  normal,  natural  condition  of  gas. 
Several  substances,  when  heated,  yield  oxygen ; but,  for  convenience 
and  economy,  the  crystalline  body  known  as  chlorate  of  potassium  is 
best  fitted  for  the  experiment.  The  size  and  form  of  the  vessel  in 
which  to  heat  it  will  mainly  depend  on  the  quantity  required;  but 
for  the  purposes  of  the  student  the  best  is  a test-tube,  an  instrument 
in  constant  requisition  in  studying  practical  chemistry.  It  is  simply 
a thin  tube  of  glass,  a few  inches  in  length,  and  half  or  three-quarters 
of  an  inch  in  diameter,  closed  by  fusion  at  one  end.  It  is  made  of 
thin  glass,  in  order  that  it  may  be  rapidly  heated  or  cooled  without 
risk  of  fracture. 

Outline  of  the  Pi'ocess. — Heat  chlorate  of  potassium  (say, 
as  much  as  will  lie  on  a shilling)  in  a test-tube,  by  means 
of  a spirit-  or  gas-flame  ; gaseous  oxygen  is  quickly  evolved. 
Before  applying  heat,  however,  provision  should  be  made 
for  collecting  the  gas. 

Collection  of  Gases, — Procure  a piece  of  glass  tubing 
about  the  thickness  of  a quill  pen,  and  a foot  or  eighteen 
inches  long,  and  fit  it  accurately  to  the  test-tube  by  means 
of  a cork.  (Longer  tubes  may  be  neatly  cut  to  any  size 
by  smartly  drawing  the  edge  of  a triangular  file  across  the 
glass  at  the  required  point,  then  clasping  the  tube,  the 
scratch  being  between  the  hands,  and  pulling  the  portions 
asunder,  force  being  exerted  in  a slightly  curved  direction 
so  as  to  open  out  the  crack  which  the  file  has  commenced.) 
The  tube  is  fixed  in  the  cork  through  a round  hole  made 
by  the  aid  of  a red-hot  wire,  or,  better,  a rat-tail  file,  or, 
best  of  all,  by  one  of  a set  of  cork-borers — pieces  of  brass 
tubing  sharpened  at  one  end  and  having  a flat  head  at  the 
other.  Setting  aside  the  test-tube  for  a few  minutes,  pro- 
ceed to  bend  the  long  piece  of  tubing  to  the  most  conve- 
nient shape  for  collecting  the  gas. 

To  bend  Glass^  Tubes, — Hold  the  part  of  the  tube  re- 
quired to  be  bent  in  any  gas- or  spirit-flame  (a  fish-tail  gas- 
jet  answers  very  well),  constantl}' rotating  it,  so  that  about 
an  inch  of  the  glass  becomes  heated.  It  will  soon  be  felt 
to  soften,  and  will  then,  yielding  to  the  gentle  pressure  of 
the  fingers,  assume  an}-  required  angle.  In  the  present 
case,  the  tube  should  be  heated  at  about  four  inches  from 
the  extiemity  to  which  the  cork  is  attached,  and  bent  to 
an  angle  of  about  90  degrees. 

Source  of  Heat. — The  source  of  heat  for  the  test-tube  may  be  the 
flame  of  an  ordinary  s])irit-lamp,  or,  still  better  where  coal-gas  is 
procurable,  a mixture  of  the  latter  with  air.  The  simple  flame  of  a 
common  argand  gas-burner  is  preferred  by  some  operators,  especially 


OXYGEN. 


11 


when  the  usual  gas  chimney  is  replaced  by  a metal  one  about  four  or 
five  inches  long.  If  a piece,  or  cap,  of  wire  gauze  be  fixed  on  to 
the  top  of  the  metal  chimney,  then  the  unlit  gas  which  issues  from 
the  jets  of  the  argand  burner  become  mixed  with  air  inside  the 
chimney,  and  the  mixture,  when  lit  on  the  outer  side  of  the  gauze, 
burns  with  a flame  as  smokeless  and  as  little  colored  as  that  of  a 
spirit-lamp.  Gas-lamps  especially  constructed  to  burn  a mixture  of 
coal-gas  and  air  are  sold  by  chemical-apparatus  manufacturers. 

Collection^  etc.  {continued).-— Yit  the  cork  and  bent  tube 
into  the  test-tube;  the  apparatus  will  then  be  ready  for 
delivering  gas  at  a convenient  distance  from  the  heated 
portion  of  the  arrangement.  To  collect  it,  have  ready 
three  or  four  test-tubes  (or  small  wide-mouthed  bottles) 
filled  with  water,  and  inverted  in  a basin,  or  other  similar 
vessel,  also  containing  water,  taking  care  to  keep  the 
mouths  of  the  tubes  a little  below  the  surface.  Now 
apply  heat  to  the  chlorate  contained  in  the  test-tube,  and 
so  arrange  the  open  end  of  the  bent  tube  under  the  water 
that  the  gas  which  presently  issues  may  bubble  into  and 
gradually  fill  the  inverted  test-tubes.  The  first  tubeful 
may  be  rejected,  as  it  probably  consists  of  little  more  than 
the  air  originally  in  the  apparatus,  and  w'hich  has  been 
displaced  by  the  oxygen.  That  which  comes  afterwards 
will  be  pure  oxygen. 

As  each  tube  or  bottle  is  collected,  the  mouth  (still 
under  the  surface  of  the  water)  may  be  closed  by  a cork 
and  set  aside  ; or  a little  cup  (such  as  a porcelain  crucible 
or  small  gallipot)  may  be  brought  under  the  mouth,  and 
the  cup,  with  the  mouth  of  the  tube  in  it,  be  lifted  out  of 
the  water  and  placed  close  by  till  wanted,  the  water  re- 
maining in  the  cup  efiectually  preventing  the  gas  from 
escaping. 

On  the  large  scale,  oxygen  may  be  made  in  the  same  way,  larger 
vessels  (glass  flasks  or  iron  bottles)  being  employed.  Less  heat  also 
will  be  necessary  if  the  chlorate  of  potassium  be  previously  mixed 
with  very  fine  sand,  or,  still  better,  with  about  an  equal  weight  of 
common  black  oxide  of  manganese. 

Note  on  the  Collection  and  Storage  of  Gases. — It  may  be  as 
well  to  state  that  nearly  all  gases,  whether  for  experimental  or 
practical  purposes,  are  collected  and  stored  in  a similar  manner. 
Even  coal-gas  is  generated  at  gas-works  in  iron  retorts  very  much 
the  shape  of  test-tubes,  only  they  are  as  many  feet  long  as  a test- 
tube  is  inches ; and  the  well-known  gigantic  gas-holders  may  be 
viewed  as  inverted  iron  test-tubes  of  great  diameter. 

: Properties. — Oxygen  is  a colorless  gas.  It  cannot  be 

f liquefied  or  solidified.  Obviously  it  is  not  very  soluble 

2* 


18 


NON  - METAL  Lie  ELEMENTS. 


in  water,  or  it  could  not  be  collected  by  the  aid  of  that 
liquid. 

Oxygen  is  soluble  to  a certain  extent,  however  (about  3 volumes 
in  100,  at  common  temperatures),  or  fishes  could  not  breathe. 

Other  noticeable  features  are  its  want  of  taste  and  smell. 
]Sext,  to  show  the  relation  of  ox^^gen  to  combustion,  re- 
move one  of  the  tubes  from  the  water  b}"  placing  the 
thumb  over  its  mouth,  apply  for  a second  a lighted  wood 
match  to  the  orifice ; the  gas  will  be  found  to  be  incom- 
bustible. Extinguish  the  flame  of  the  match,  and  then 
quickly  introduce  the  still  incandescent  carbonaceous  ex- 
tremity of  the  wood  halfway  down  the  test-tube  ; the  wood 
will  at  once  burst  into  flame,  owing  to  the  extreme  vio- 
lence with  which  oxygen  supports  combustion.  These 
tests  of  the  presence  of  oxygen  may  also  be  applied  at  the 
extremity  of  the  delivery-tube  whilst  the  gas  is  being 
evolved.  (It  is  desirable  to  retain  two  tubes  of  the  gas 
for  use  in  subsequent  experiments  ; also  one  tube  in  which 
only  one-third  of  the  water  has  been  displaced  by  oxygen.) 

Relation  of  Oxygen  to  Animal  and  Vegetable  Life. — Not  only 
the  carbon  at  the  end  of  a piece  of  charred  wood,  but  any  other 
substance  that  will  burn  in  air  (which,  as  will  be  seen  presently,  is 
diluted  oxygen)  will  burn  more  brilliantly  in  pure  oxygen.  The 
warmth  of  the  body  of  animals  is  kept  up  by  the  continuous  burning 
of  the  carbonaceous  matter  of  the  blood  in  the  oxygen  of  the  air 
drawn  into  the  lungs.  The  product  of  this  combustion-  is  a gaseous 
compound  of  carbon  and  oxygen  termed  carbonic  acid  gas,  a gas 
which,  in  sunlight,  is  decomposed  in  the  cells  of  plants  with  fixation 
of  the  carbon  and  liberation  of  the  oxygen  ; hence  the  atmosphere  is 
kept  constant  in  composition. 

Memorandum. — At  present  it  is  not  advisable  that  the  reader 
should  trouble  himself  with  the  consideration  of  the  chemical  action 
which  occurs  either  in  the  elimination  of  oxygen  from  its  compounds, 
or  in  the  separation  of  any  of  the  following  non-metallic  elements 
from  their  combinations.  It  is  to  the  properties  of  the  elements 
themselves  that  he  should  restrict  his  attention.  Working  thus  from 
simple  to  more  complex  facts,  he  will  in  due  time  find  that  the  com- 
prehension of  such  actions  as  occur  in  the  preparation  of  these  few 
elements  will  be  easier  than  if  he  attempted  their  full  study  now. 

HYDROGEN. 

Preparation  and  Collection, — The  element  of  hydrogen 
is  also  a gas,*  and  is  obtainable  from  its  commonest  com- 

* Graham  obtained  alloys  of  hydrogen  with  palladium  and  oth«r 
metals,  compounds  in  which  several  hundred  times  its  bulk  of  gas 


HYDROGEN* 


19 


pound,  water  (of  which  one-ninth  by  weight  is  hydrogen), 
i)y  the  agency  of  hot  zinc  or  iron,  but  more  conveniently 
by  the  action  of  either  of  these  metals  on  cold  diluted  sul- 
phuric acid.  The  apparatus  used  for  making  oxygen  may 
be  employed  for  this  experiment ; but  no  lamp  is  required. 
Place  several  pieces  of  thin  zinc*  in  the  generating-tube, 
or  in  any  common  glass  bottle,  and  cover  them  with  water. 
The  collecting-tubes  (these  may  be  wide-mouthed  bottles) 
being  ready,  add  strong  sulphuric  acid  (oil  of  vitriol)  to 
the  zinc  and  water,  in  the  proportion  of  about  1 volume 
of  acid  to  5 of  water,  and  fit  on  the  delivery-tube  ; the 
hydrogen  is  at  once  evolved.  Having  rejected  the  first 
portions  (or  having  waited  until  the  air  originally  in  the 
bottle  may  be  considered  to  be  all  expelled),  collect  four 
or  five  tubes  of  the  gas  in  the  manner  described  under 
Oxygen. 

In  making  larger  quantities  bottles  of  appropriate  size  may  be 
employed. 

Other  metals,  notably  potassium  and  sodium,  liberate  hydrogen 
the  moment  they  come  into  contact  with  water;  but  the  processes 
are  not  economical. 

Properties — Like  oxygen,  h^^drogen  is  invisible,  inodor- 
ous, and  tasteless.  If  made  with  iron  it  has  a strong  smell, 
but  this  is  due  to  impurities  contained  in  the  metal. 

Apply  a flame  to  the  mouth  of  the  delivery  tube  (care 
being  taken  that  the  gas  is  coming  off  briskl}" — a guaran- 
tee that  no  air  remains  in  the  generating  vessel) ; ignition 
of  the  hydrogen  ensues,  showing  that,  unlike  oxygen,  it  is 
combustible. 

Immerse  a lighted  match  into  a tube  (or  wide-mouthed 
bottle)  containing  hydrogen  ; the  gas  is  ignited,  but  the 
match  becomes  extinguished.  This  shows  that  hydrogen 
is  not  a supporter  of  combustion. 

is  retained  by  tlie  metal  in  vacuo  or  even  at  a red  beat.  This  is 
physical  confirmation  of  the  opinion  long  held  by  chemists,  that 
hydrogen  is  a gaseous  metal.  Graham  termed  it  hydrogenium  (other 
chemists  hydrium),  and  considered  ’ its  relative  weight  in  the  solid 
state  to  be  nearly  three-fourths  that  of  water. 

* The  best  form  is  granulated  zinc  {Zincum  Granulatum,  B.  P.) 
made  by  heating  scraps  of  common  sheet  zinc  in  a ladle  over  a fire, 
and  as  soon  as  melted  pouring,  in  a slow  stream,  into  a pail  of  water 
from  a height  of  8 or  10  feet.  Each  drop  of  zinc  thus  yields  a thin 
little  bell,  which,  for  its  weight,  presents  a large  surface  to  the  action 
of  the  acid  water.  If  the  zinc  is  allowed  to  become  hotter  than  ne- 
cessary, the  little  bells  will  not  be  formed. 


20 


NON  - METAL  Lie  ELEMENTS. 


Hydrogen  in  burning  unites  with  the  oxygen  of  the  air 
and  forms  water,  wdiich  may  be  condensed  on  a cool  glass 
or  other  surface.  Prove  this  by  holding  a glass  vessel  a 
few  inches  above  a hydrogen-flame.  In  burning  the  h3^dro- 
gen  contained  in  one  of  the  tubes  or  bottles,  the  flame  is 
best  seen  when  the  tube  is  held  mouth  upwards,  and  water 
poured  in  so  as  to  force  out  the  gas  gradualljL 

If,  instead  of  this  gradual  combination  of  the  two  ele- 
ments oxj^gen  and  h^^drogen,  they  be  mixed  together  in 
the  right  proportions  and  then  ignited,  the}^  will  rapidly 
combine,  in  other  words,  explosion  results.  Prepare  a mix- 
ture of  this  kind  b^^  filling  up  with  hj’drogen  a test-tube 
from  which  one-third  of  the  water  has  been  expelled  by 
oxj^gen.  Remove  the  tube  from  the  w^ater,  placing  a finger 
over  the  mouth,  and,  having  a lighted  match  read}^,  appl^^ 
the  flame;  a slight  explosion  will  result,  owing  to  the  in- 
stantaneous combination  of  the  two  elements,  and  the  ex- 
pansive force  of  the  steam  produced.  If  an^dhing  larger 
than  a test-tube  is  emplo^^ed  in  this  experiment,  it  should 
be  a soda-water  bottle,  or  some  such  vessel  equally  strong. 

These  two  gases  thus  unite  at  a temperature  considerably  above 
that  of  boiling  water,  two  volumes  of  hydrogen  and  one  of  oxygen 
yielding  two  volumes  of  gaseous  water  (true  steam). 

The  noise  of  such  explosions  is  caused  by  concussion  between  the 
particles  of  the  gaseous  body  and  those  of  air. 

The  force  of  the  explosion,  or,  in  other  words,  the  expansive  force 
of  the  highly-heated  steam  produced,  is  exceedingly  slight,  certainly 
very  far  below  that  necessary  to  break  the  test-tube.  Some  force, 
however,  is  exerted,  and  hence  the  necessity  of  the  precaution  pre- 
viously suggested  of  allowing  all  the  air  which  may  be  in  a hydro- 
gen-apparatus to  escape  before  proceeding  with  the  experiments.  If 
a flame  be  applied  to  the  delivery-tube  before  all  the  air  is  expelled, 
the  probable  result  will  be  ignition  of  the  mixture  of  hydrogen  and 
oxygen  (of  the  air)  and  consequent  explosion.  But  even  in  this  case 
the  generating-vessel  is  not  often  fractured  unless  it  be  large  and  of 
thin  glass,  the  ordinary  effect  being  that  the  cork  is  blown  out,  and 
the  delivery-tube  broken  on  falling  to  the  ground. 

Hydrogen  is  a prominent  constituent  of  all  the  substances  used  for 
producing  artificial  light,  such  as  tallow,  oil,  and  coal-gas.  The  ex- 
plosive force  of  large  quantities,  such  as  a roomful,  of  coal-gas  and 
air,  though  vastly  below  that  of  an  equal  weight  of  gunpowder,  is 
well  known  to  be  sufficient  at  least  to  blow  out  that  side  of  the  room 
which  offers  least  resistance. 

The  composition  of  ivater  can  be  proved  analytically  as  well  as 
synthetically,  a current  of  electricity  decomposing  it  into  its  con- 
stituent gases,  twice  as  much  hydrogen  as  oxygen,  by  volume,  being 
produced. 


HYDROGEN. 


21 


Combustion  (from  comhuro,  to  burn). — The  experiments  with 
hydrogen  and  oxygen  illustrate  the  true  character  of  combustion. 
Whenever  chemical  combination  is  sufficiently  intense  to  be  accom- 
panied by  heat  and  light,  the  materials  are  said  to  undergo  combus- 
tion. Combustion  only  occurs  at  the  line  of  contact  of  the  combining 
bodies ; a jet  of  oxygen  will  burn,  in  an  atmosphere  of  hydrogen 
quite  as  easily  as  a jet  of  hydrogen  in  oxygen.  A jet  of  air  (diluted 
oxygen)  will  burn  as  readily  in  a jar  of  coal-gas  as  a jet  of  coal-gas 
burns  in  air ; each  is  combustible,  each  supports  the  combustion  of 
the  other.  Hence  the  terms  combustible  and  supporter  of  combus- 
tion are  purely  conventional,  and  only  applicable  so  long  as  the  cir- 
cumstances under  which  they  are  applied  remain  the  same.  In  the 
case  of  substances  burning  in  air,  the  conditions  are,  practically, 
always  the  same;  hence  no  confusion  arises  from  regarding  air  as  the 
great  supporter  of  combustion,  and  bodies  which  burn  in  it  as  being 
combustible. 

Structure  of  Flame.- — A candle-flame  or  oil-flame  is  a jet  of  gas 
intensely  heated ; the  central  portion  is  unburnt  gas ; the  next  envelope 
is  formed  of  partially  burnt  and  very  dense  gaseous  particles  heated 
sufficiently  high  to  give  light,  and  the  outer  cone  of  completely  burnt 
gases.  Air  made,  by  any  mechanical  contrivance  of  burner,  to  mix 
with  the  interior  of  a flame  at  once  burns  up,  or  perhaps  prevents  the 
formation  of  dense  gases,  giving  a hotter,  but  non-luminous,  jet.  The 
“Bunsen”  gas-burners  commonly  used  in  chemical  laboratories  are 
constructed  on  this  principle : their  flame  has  the  additional  advan- 
tage of  not  yielding  a deposition  of  soot. 

In  the  Bunsen  gas-burner  a mixture  of  gas  and  air  passes  along  a 
pipe.  It  only  burns  at  the  end,  and  not  within  the  pipe,  because  the 
metal  of  the  burner,  by  conducting  heat  aw^ay,  cools  the  mixture 
below  the  temperature  at  which  it  can  ignite.  The  Davy  safety- 
lamp  acts  on  the  same  principle  : a wire-gauze  cage  surrounds  an  oil- 
flame  ; an  inflammable  mixture  of  gas  (fire-damp)  and  air  can  pass 
through  the  gauze  and  catch  fire  and  burn  inside  ; but  the  flame 
cannot  be  communicated  to  the  mixture  outside,  because  the  metal 
of  the  gauze  and  other  parts  cools  down  the  gas  below  the  tempera- 
ture at  which  it  can  burn. 

Properties  (continued). — Hydrogen  is  the  lightest  sub- 
stance known.  It  Avas  formerly  used  for  filling  balloons, 
but  was  soon  superseded  by  coal-gas.  Coal  gas  is  not  so 
light  as  hydrogen,  but  is  cheaper  and  more  easily  obtained. 
The  lightness  of  hydrogen  may  be  rendered  evident  by  the 
following  experiment : Fill  two  test-tubes  with  the  gas, 
and  hold  one  with  its  mouth  downwards  and  the  other 
with  its  mouth  upwards.  The  hydrogen  will  have  escaped 
from  the  latter  in  a few  seconds,  whereas  the  former  will 
still  contain  the  gas  after  the  lapse  of  some  minutes.  This 
may  be  proved  by  applying  a lighted  match  to  the  mouths 
of  the  respective  tubes. 


22 


NON-METALLIC  ELEMENTS. 


The  relative  weight  or  specific  gravity  of  oxygen  is  sixteen  times 
that  of  hydrogen.  A vessel  holding  one  grain  of  hydrogen  will  hold 
sixteen  grains  of  oxygen.  The  relation  of  the  weight  of  hydrogen 
to  air  is  as  1 to  14.44  or  as  0.0693  to  1.0.  One  grain  of  hydrogen  by 
weight  would  measure  about  27  fluidounces. 

Mem, — It  is  desirable  to  retain  two  tubes  of  hydrogen  for  use  in 
subsequent  experiments. 

Diffusion  of  Gases, — Hydrogen  cannot  be  kept  in  such  vessels  as 
the  inverted  test-tube  ; for,  though  much  lighter  than  air,  it  diffuses 
downwards  into  the  air,  while  the  air,  though  much  heavier,  diffuses 
upwards  into  the  hydrogen.  This  power  of  diffusion  is  character- 
istic of  all  gases,  and  proceeds  according  to  a fixed  law,  namely,  “ in 
inverse  proportion  to  the  square  root  of  the  specific  gravity  of  the 
gas”  (Graham).  Thus  hydrogen  diffuses  four  times  faster  than 
oxygen. 


PHOSPHORUS. 

Appearance  and  Source, — Phosphorus  [Phosphorus,  B.  P.  and 
U.  S.  P.)  is  a solid  element,  in  appearance  and  consistence  resem- 
bling white  wax ; but  it  gradually  becomes  yellow  by  exposure  to 
light.  It  is  a characteristic  constituent  of  bones,  and  is  always  pre- 
pared from  that  source  by  a process  which  will  be  subsequently 
described. 

Caution, — Phosphorus,  on  account  of  its  great  affinity  for  oxygen, 
takes  fire  very  readily,  and  should  therefore  be  kept  under  water. 
When  wanted  for  use  it  must  be  cut  under  water.  It  is  employed  in 
tipping  lucifers,  though  red  or  amorphous  phosphorus  [vide  Index) 
is  least  objectionable  for  this  purpose. 

Properties, — Dry  a piece  about  one-fourth  the  size  of  a 
pea  by  quickly  and  carefully  pressing  it  between  the  folds 
of  porous  (filter  or  blotting)  paper;  place  it  on  a plate, 
and  ignite  b}^  touching  it  with  a piece  of  warm  wire  or 
wood.  Observe  that  the  product  of  combustion  is  a dense 
wdiite  smoke,  which  must  be  confined  at  once  by^  placing  an 
inverted  tumbler,  test-glass,  or  other  similar  vessel  over 
the  phosphorus.  The  fumes  rapidly  aggregate,  and  fall  in 
white  flakes  on  the  plate.  When  this  has  taken  place,  and 
the  phosphorus  is  no  longer  burning,  moisten  the  powder 
with  a drop  or  two  of  water,  and  observe  that  some  of  the 
water  is  converted  into  steam,  an  effect  duetto  the  intense 
affinity^  with  which  the  two  combine. 

The  powder  produced  by  the  combustion  of  phosphorus  is  phos- 
phoric anhydride ; the  combination  of  the  latter  with  the  elements 
of  water  produces  a variety  of  phosphoric  acid  which  dissolves  in  the 
water,  forming  on  standing  a dilute  solution  of  ordinary  phosphoric 
acid.  The  Diluted  Phosphoric  Acid  of  the  British  and  United  States 
Pharmacopoeias  is  a somewhat  similar  solution,  made,  however,  in  a 
different  way,  and  of  a definite  strength. 


NITROGEN. 


23 


NITROGEN. 

Source. — The  chief  source  of  this  gaseous  element  is  the  atmo- 
sphere, nearly  four-fifths  of  which  consists  of  nitrogen  (the  remaining 
fifth  being  almost  entirely  oxygen). 

Preparation. — Burn  a piece  of  dried  phosphorus,  the  size 
of  a pea,  in  a confined  portion  of  air.  The  oxygen  is  thus 
removed,  and  nitrogen  alone  remains.  The  readiest  mode 
of  performing  this  experiment  is  to  fix  a piece  of  eartlien- 
ware  (the  lid  of  a small  porcelain  crucible  answers  very 
well)  on  a thin  piece  of  cork,  so  that  it  may  float  in  a dish 
of  water.  Place  the  phosphorus  on  the  lid,  ignite  hy  a warm 
rod,  and  then  invert  a tumbler,  or  any  glass  vessel  of  about 
a half-pint  capacity,  over  the  burning  phosphorus,  so  that 
the  glass  may  dip  into  the  water.  Let  the  arrangement 
rest  for  a short  time  for  the  fumes  of  phosphoric  anhydride 
to  subside  and  dissolve  in  the  water,  and  then  decant  the 
gas  into  test-tubes  in  the  manner  already  indicated,  using 
a vessel  of  water  of  sufficient  depth  to  admit  of  the  glass 
containing  the  nitrogen  to  be  turned  on  one  side  without 
air  gaining  access. 

Larger  quantities  are  made  in  the  same  way.  Other  combustibles, 
such  as  sulphur  or  a candle,  might  be  used  to  burn  out  the  oxygen 
from  a given  quantity  of  air,  but  none  answer  so  quickly  and  com- 
pletely as  phosphorus  ; added  to  which,  the  product  of  their  combus- 
tion would  not  always  be  dissolved  by  water,  but  would  remain  with 
and  contaminate  the  nitrogen. 

3Iem. — The  statement  concerning  the  composition  of  the  air  is 
roughly  confirmed  in  preparing  nitrogen,  about  one-fifth  of  the  volume 
of  the  air  originally  in  the  glass  vessel  having  disappeared,  its  place 
being  occupied  by  water  from  the  dish. 

Properties. — Like  ox3^gen  and  h^^drogen,  nitrogen  is  in- 
visible, tasteless,  and  inodorous.  It  is  only  slightly  soluble 
in  water.  It  is  distinguished  from  all  other  gases  by  the 
absence  of  any  characteristic  or  positive  properties.  Apply 
a flame  to  some  contained  in  a tube  ; it  will  be  found  to  be 
incombustible.  Immerse  a lighted  match  in  the  gas  ; the 
flame  is  extinguished,  showing  that  nitrogen  is  a rion-sup- 
IDorter  of  combustion. 

The  chief  office  of  nitrogen  in  the  air  is  to  dilute  the  energetic 
oxygen,  a mere  mechanical  mixture  resulting.  The  chemical  com- 
pounds of  nitrogen  and  oxygen  are  numerous  (;vide  Index).  The 
compound  formed  by  the  union  of  nitrogen  with  hydrogen  is  gaseous 
ammonia. 


24 


NON  - METALLIC  ELEMENTS. 


Nitrogen  is  fourteen  times  as  heavy  as  hj^drogen. 

The  air  is  nearly  fourteen  and  a,  half  (14.44)  times  as  heavy  as 
hydrogen.  Its  average  composition,  including  minor  constituents, 
which  will  be  referred  to  subsequently,  is  as  follows  : — 

Composition  of  the  Atmosphere. 

In  100  volumes. 


Oxygen 20.61 

Nitrogen 77.95 

Carbonic  acid  gas  ....  .04 

Aqueous  vapor  ......  1.40 

Nitric  acid 1 

Ammonia > traces. 

Carburetted  hydrogen  . . . . ] 

Sulphuretted  hydrogen  . . .1  traces  in 

Sulphurous  acid j towns. 


The  above  proportions  are  by  volume.  By  weight  there  will  be 
nearly  23  parts  of  oxygen  to  nearly  77  of  nitrogen,  oxygen  being  the 
heavier  in  the  ratio  of  16  to  14.  Ozone  {vide  Index)  is  also  said  to 
be  a normal  constituent  of  air. 

CHLORINE. 

Source. — This  element  is  a gas.  Its  chief  source  is  common  salt, 
more  than  half  of  which  is  chlorine. 

Preparation. — About  a quarter  of  an  ounce  of  salt  and 
the  same  amount  of  black  oxide  of  manganese  are  placed 
in  a test-tube  with  sufficient  water  to  cover  them  ; on  add- 
ing a small  quantity  of  sulphuric  acid,  the  evolution  of 
chlorine  commences. 

Another  Process. — As  the  action  of  the  sulphuric  acid  on  the 
salt  in  the  above  process  is  mainly  to  give  hydrochloric  acid,  the 
latter  acid  (about  4 parts)  and  the  black  oxide  of  manganese  (about 
1 part)  may  be  used  in  making  the  gas,  instead  of  salt,  sulphuric 
acid,  and  black  oxide  of  manganese.  This  is  the  process  of  the 
British  and  United  States  Pharmacopoeias. 

Larger  quantities  may  be  made  from  hydrochloric  acid  and  black 
oxide  of  manganese  (about  4 parts  to  1)  in  a Florence  flask,  fitted 
with  a delivery-tube,  the  flask  being  supported  over  a flame  by  the 
ring  of  a retort  stand  or  any  similar  mechanical  contrivance. 

Mem. — Flasks  and  similar  glass  vessels  are  less  liable  to  fracture 
if  protected  from  the  direct  action  of  the  flame  by  being  placed  on  a 
piece  of  wire  gauze  2 to  4 inches  square,  or  on  a sand-bath,  that  is, 
a saucer-shaped  tray  of  sheet  iron,  on  which  a thin  layer  of  sand  is 
placed. 

Collection  and  Properties. — Chlorine  is  a most  suflTo- 
cating  gas.  Great  care  must  consequently  be  observed  in 


CHLORINE. 


25 


experimenting  with  this  element.  As  soon  as  its  pene- 
trating odor  indicates  that  it  is  escaping  from  the  test- 
tube,  the  cork  and  delivery-tube  should  be  fitted  on,  and 
the  gas  allowed  to  pass  to  the  bottom  of  another  test-tube 
half  filled  with  water.  When  thirty  or  forty  small  bubbles 
have  passed,  their  evolution  being  assisted  by  slightly 
heating  the  generating-tube,  the  latter  should  be  removed 
to  the  cupboard  usually  provided  in  laboratories  for  per- 
forming operations  with  noxious  gases,  or  dismounted, 
and  the  contents  washed  away.  The  water  in  the  collect- 
ing-tube will  now  be  found  to  smell  of  the  gas,  chlorine 
being,  in  fact,  soluble  in  about  half  its  bulk  of  water. 
Chlorine-water  is  official*  in  the  British  and  United  States 
Pharmacopoeias  {Liquor  Ghlori^  B.  P.,  Aqua  Ghlorinii^ 
U.  S.  P.). 

The  Vapor  Ghlori,  B.  P.,  or  Inhalation  of  Chlorine,  is  simply 
moist  chlorinated  lime  so  placed  that  some  of  the  chlorine  given  off 
may  be  inhaled. 

During  these  manipulations  the  operator  will  have  noticed  that 
chlorine  is  of  a light  green  color.  That  tint  is  readily  observed  when 
the  gas  is  collected  in  large  vessels.  As  it  is  soluble  in  water  (2|- 
vols.  in  1 vol.  at  60^  F.),  it  cannot  be  economically  stored  over  that 
liquid.  Being,  however,  nearly  twice  and  a half  as  heavy  as  air,  it 
may  be  collected  by  simply  allowing  the  delivery-tube  to  pass  to  the 
bottom  of  the  test-tube  or  dry  bottle. 

The  distinctive  property  of  chlorine  is  its  bleaching- 
power.  Prepare  some  colored  liquid  by  placing  a few  chips 
of  logwood  or  other  dyeing  material  in  a test-tube  half  full 
of  hot  water.  Pour  off  some  of  this  red  decoction  into 
another  tube,  add  a few  drops  of  the  chlorine-water,  and 
note  how  rapidly  the  red  color  is  destroyed. 

Chlorine  readily  decomposes  noxious  gases,  and  hence  is  one  of 
the  most  powerful  of  the  deodorizers.  Used  in  excess  it  arrests  and 
prevents  putrefaction,  hence  it  is  one  of  the  best  of  disinfectants. 

* The  Pharmacopoeia  and  all  in  it  are  official  {office,  Fr.  from  L. 
officium,  an  office).  There  are  many  things  which  in  pharmacy  are 
officinal  (Fr.  from  L.  officina,  a shop)  but  not  official.  To  restrict 
the  word  officinal  to  the  contents  of  a pharmacist’s  shop,  and  to  that 
portion  of  the  contents  which  is  Pharmacopoeial,  is  radically  wrong, 
and  should  be  avoided.  ‘‘An  official  formula  is  one  given  under 
authority.  An  officinal  formula  is  one  made  in  obedience  to  the  cus- 
tomary usage  of  the  shop  (officina)..  To  state  that  any  preparation 
under  the  sanction  of  the  Pharmacopoeia  is  officinal,  is  a misappre- 
hension of  the  meaning  of  the  word.” — Brough, 

3 


26 


NON  - METALLIC  ELEMENTS. 


Combination  of  Hydrogen  with  Chlorine^  forming  Hydro- 
chloric  Acid, — If  an  opportunity  occurs  of  generating  the 
gas  in  a closed  chamber  or  in  the  open  air,  a test-tube  of 
the  same  size  as  one  of  those  in  which  hydrogen  has  been 
retained  from  a previous  operation,  is  filled  with  the  gas. 
The  hydrogen-tube  is  then  inverted  over  that  containing 
the  chlorine,  the  mouths  being  kept  together  by  encircling 
them  with  a fin'ger.  After  the  gases  have  mixed,  the  mouths 
of  the  tubes  are  quickly  in  succession  brought  near  a flame, 
when  explosion  occurs,  and  fumes  of  hydrochloric  acid 
combined  with  the  moisture  of  the  air  are  formed.  The 
Hydrochloric  Acid  of  pharmacy  {Acidum  Hydrochloricuin,^ 
B.  P.,  Acidum  Muriaticum,^  U.  S.  P.)  is  a solution  of  the 
gas  (made  in  a more  economical  way)  in  water. 

The  foregoing  experiment  affords  evidence  of  the  powerful  affinity 
of  chlorine  and  hydrogen  for  each  other.  Chlorine  dissolved  in  water 
will,  in  sunlight,  slowly  remove  hydrogen  from  some  of  the  water  and 
liberate  oxygen.  The  bleaching-power  of  chlorine  is  generally  re- 
ferred to  this  oxidizing  effect  which  it  produces  in  presence  of  water  ; 
for  dry  chlorine  does  not  bleach. 

Density. — Chlorine  is  thirty-five  and  a half  times  as  heavy  as 
hydrogen. 

SULPHUR,  CARBON,  IODINE. 

The  physical  properties  of  those  elements  (color,  hardness,  weight, 
etc.)  are  familiar.  Their  leading  chemical  characters  will  also  be 
understood  when  a few  facts  concerning  each  are  made  the  subject  of 
experiment. 

Sulphur. — Burn  a small  piece  of  sulphur;  a penetrating 
odor  is  produced,  due  to  the  formation  of  a colorless  gas, 
the  same  as  that  formed  on  igniting  a sulphur-tipped  lucifer 
match. 

This  product  is  a perfectly  definite  chemical  compound  of  the 
oxygen  of  the  air  with  the  sulphur.  It  is  termed  sulphurous  anhy- 
dride or  sulphurous  acid  gas. 

Carbon  is  familiar  in  the  forms  of  soot,  coke,  charcoal, 
graphite  (plumbago,  popularly  termed  blacklead),  and  dia- 
mond. The  presence  of  carbon  in  wood,  and  in  other  vege- 
table and  animal  matter,  is  at  once  rendered  evident  by 
heat.  Place  a little  tartaric  acid  on  the  end  of  a knife  in  a 
flame ; the  blackening  that  occurs  is  due  to  the  separation 
of  carbon.  The  black  matter  at  the  extremity  of  a piece 
of  half-burned  wood  is  also  carbon. 


THE  ELEMENTS,  THEIR  SYMBOLS,  ETC.  27 

Carbon,  like  hydrogen,  phosphorus,  and  sulphur,  has  a great 
affinity  for  oxygen  at  high  temperatures.  A striking  evidence  of 
that  affinity  is  the  evolution  of  sufficient  heat  to  make  the  materials 
concerned  red  or  even  white-hot.  When  ignited  in  the  dilute  oxygen 
of  the  air,  carbon  simply  burns  with  a moderate  glow,  as  seen  in  an 
ordinary  coke  or  charcoal  fire,  but  when  ignited  in  pure  oxygen,  the 
intensity  of  its  combination  is  greatly  exalted.  The  product  of  the 
combination  of  the  two  elements,  if  the  oxygen  be  in  excess,  is  an  in- 
visible gaseous  body  termed  carbonic  acid  gas ; if  the  carbon  be  in 
excess,  another  invisible  gas  termed  carbonic  oxide  results. 

Iodine. — A prominent  chemical  characteristic  of  iodine 
is  its  great  affinity  for  metals.  Place  a piece  of  iodine, 
about  the  size  of  a pea,  in  a test-tube  with  a small  quantity 
of  water,  and  add  a few  iron-filings  or  small  nails.  On 
gently'  warming  this  mechanical  mixture,  or  even  shaking 
if  longer  time  be  allowed,  the  color  and  odor  of  the  iodine 
disappear;  it  has  chemically  combined  with  the  iron;  a 
chemical  compound  has  been  produced.  If  the  solution  be 
filtered,  a clear  aqueous  solution  of  the  compound  of  the 
two  elements  is  obtained. 

This  compound  is  an  iodide  of  iron.  Its  solution,  made  as  above, 
and  mixed  with  sugar,  forms,  when  of  a certain  strength,  the  ordinary 
Syrup  of  Iodide  of  Iron  of  pharmacy  {Syrupus  Ferri  lodidi,  B.  P. 
and  IT.  S.  P.).  A strong  solution  mixed  with  sugar  and  liquorice- 
root  (sugar,  liquorice,  liquorice-root,  gum  Arabic,  and  reduced  iron, 
U.  S.  P.)  constitutes  the  corresponding  Pill  [Pilida  Ferri  lodidi^ 
B.  P.  and  U.  S.  P.).  The  solid  iodide  [Ferri  lodidiim,  B.  P.)  is 
obtained  on  removing  the  water  of  the  above  solution  by  evaporation. 

Sulphur  and  Iron,  also,  when  very  strongly  heated,  chemically  com- 
bine to  form  a substance  which  has  none  of  the  properties  of  a mix- 
ture of  sulphur  and  iron,  that  is,  has  none  of  the  characters  of  sulphur 
and  none  of  iron,  but  new  properties  altogether.  The  product  is 
termed  Sulphide  of  Iron.  Its  manufacture  and  uses  will  be  alluded 
to  in  treating  of  the  compounds  of  iron : it  is  mentioned  here  as  a 
simple  but  striking  illustration  of  the  difference  between  a chemical 
compound  and  a mechanical  mixture. 

THE  ELEMENTS,  THEIR  SYMBOLS,  Etc. 

From  the  foregoing  statements  a general  idea  will  have  been 
obtained  of  the  nature  of  several  of  the  more  frequently  occurring 
elements.  Some  additional  facts  concerning  them  may  be  gathered 
from  the  following  Table,  which  gives  the  name  in  full,  the  symbol 
(or  short-hand  character*)  of  the  name,  and  its  origin. 

* The  symbol  is  also  much  more  than  the  short-hand  character,  as 
will  be  presently  apparent. 


28  THE  ELEMENTS,  THEIR  SYMBOLS,  ETO. 


For  the  purposes  of  study  the  elements  may  be  divided  into  three 
classes,  viz.,  those  frequently  used  in  pharmacy,  those  seldom,  and 
those  never  used. 


Name. 

Symbol. 

Derivation  of  Name. 

Oxygen  

0 

From  ofu?  (oxus)  acid,  and  yivia-iti  (gene- 
sis) generation,  i.  e.,  generator  of  acids.  It 
was  supposed  to  enter  into  the  composition 
of  all  acids  when  first  discovered. 

Hydrogen  

H 

From  v^oop  (liudor)  water,  and  yivsa-i^  (ge- 
nesis) generation,  in  allusion  to  the  product 
of  its  combustion  in  air. 

Nitrogen 

N 

From  vhpov  (nitron),  and  yina-i^  (genesis), 
generator  of  nitre. 

Carbon  

C 

From  carho,  coal,  which  is  chiefly  carbon. 

Chlorine 

Cl 

From  ;s(^x«po?*(chloros)  green,  the  color  of 
this  element. 

Iodine 

I 

From  lov  (ion)  a violet,  and  (eidos) 

likeness,  in  reference  to  the  color  of  its 
vapor. 

Sulphur  

s 

From  sal  a salt,  and  (pur)  fire,  indi- 

cating its  combustible  qualities.  Its  com- 
mon name,  brimstone,  has  the  same  mean- 
ing, being  the  slightly  altered  Saxon  word 
hrynstone,  i.  e.,  burnstone. 

(phos)  light,  and  <f£peiv  (pherein)  to 
bear.  The  light  it  emits  may  be  seen  on 
exposing  it  in  a dark  room. 

Phosphorus 

p 

Potassium.. 

(Kalium.) 

K 

Kalium,  from  kali,  Arabic  for  ashes.  Manu- 
factories in  which  certain  compounds  of 
potassium  and  allied  sodium  salts  are  made 
are  called  alkali-works  to  this  day.  Potas- 
sium, from  pot-ash;  so  called  because  ob- 
tained by  evaporating  the  lixivium  of  wood- 
ashes  in  pots.  From  such  ashes  the  element 
was  first  obtained,  hence  the  name. 

Sodium 

(Natrium.) 

Na 

Natrium,  from  natron,  the  old  name  for 
certain  natural  deposits  of  carbonate  of 
sodium.  Sodium,  from  soda-ash  or  sod-ash, 
the  residue  of  the  combustion  of  masses  or 
sods  of  marine  plants.  These  were  the 
sources  of  the  metal. 

Ammonium 

Am 

(NH,) 

This  body  is  not  an  element ; but  its 
components  exist  in  all  ammoniacal  salts, 
and  apparently  play  the  part  of  such  ele- 
ments as  potassium  and  sodium.  Sal  am- 
moniac (chloride  of  ammonium)  was  first 
obtained  from  near  the  temple  of  Jupiter 
Ammon  in  Libya  ; hence  the  name. 

Barium 

Ba 

From  Bapvi  (barus)  heavy,  in  allusion  to 
the  high  specific  gravity  of  “heavy  spar,” 
the  most  common  of  the  barium  minerals. 

THE  ELEMENTS,  THEIR  SYMBOLS,  ETC.  29 


Name. 

Symbol. 

Derivation  of  Name. 

Calcium  

Ca 

Calx^  lime,  the  oxide  of  calcium. 

From  Magnesia,  the  name  of  the  town  (in 
Asia  Minor)  near  which  the  substance  now 
called  “ native  carbonate  of  magnesia”  was 
first  discovered. 

Magnesium 

Mg 

Iron 

(B'errum.) 

Fe 

The  spelling  is  from  the  Saxon  iren,  the 
pronunciation  probably  from  the  kindred 
Gothic  ^^iarn;'^  the  derivation  is  unknown 
to  the  author. 

Aluminium 

A1 

The  metallic  basis  of  alum  was  at  first 
confounded  with  that  of  sulphate  of  iron, 
which  was  the  alum  of  the  Romans,  and 
was  so  called  in  allusion  to  its  tonic  pro- 
perties, from  alo,  to  nourish. 

The  derivation  of  this  word  is  unknown 
to  the  author. 

Zinc  

Zn 

Arsenicum 

As 

*Apa-iviy.Qv  (arsenikon),  the  Greek  name  for 
orpiment,  a sulphide  of  arsenicum.  Com- 
mon white  arsenic  is  an  oxide  of  arsenicum. 

Antimony 

(Stibium.) 

Sb 

(stibi),  or  crrifxfja  (stimmi),  was  the 
Greek  name  for  the  native  sulphide  of  an- 
timony. The  word  aiitimony  is  said  to  be 
derived  from  avrl  (anti)  against,  and  moine, 
French  for  monk,  from  the  fact  that  certain 
monks  were  poisoned  by  it. 

Copper 

(Cuprum.) 

Cu 

From  Cyprus,  the  name  of  the  Mediterra- 
nean island  where  this  metal  was  .first 
worked. 

Lead 

(Plumbum.) 

Pb 

The  Latin  word  is  expressive  of  “ some- 
thing heavy,”  and  the  Saxon  Imd  has  a 
similar  signification. 

Mercury 

(Hydrargyrum.) 

Hg 

Hydrargyrum,  from  L'Jcup  (hudor)  water, 
and  apyvpo^  (arguros)  silver,  in  allusion  to  its 
liquid  and  lustrous  characters.  Mercury, 
after  the  messenger  of  the  gods,  on  account 
of  its  susceptibility  of  motion.  The  old 
name  quicksilver  also  indicates  its  ready 
mobility  and  argentine  appearance. 

Silver 

(Argentum.) 

Ag 

''Apyvpct;  (arguros)  silver,  from  apyoQ  (argos) 
white.  Words  resembling  the  term  silver 
occur  in  several  languages,  and  indicate  a 
white  appearance. 

The  following  are  the  names  of  some  of  the  less  frequently 
occurring  elements,  compounds  of  which,  however,  are 
alluded  to  in  the  British  and  U.  S.  Pharmacopoeias,  or  met 
with  in  pharmac}". 


3* 


30  THE  ELEMENTS,  THEIR  SYMBOLS,  ETC. 


Name. 

Symbol. 

Derivation  of  Name. 

Bromine 

Br 

From  Bfdofxo;  (bromos),  a stink.  It  has  an 
intolerable  odor. 

Fluorine 

FI 

Fluo,  to  flow.  Fluoride  of  calcium,  its 
source,  is  commonly  used  as  a flux  in  me- 
tallurgic  operations. 

Boron  

Bo 

From  borax  or  haurak^  the  Arabic  name 
of  borax,  the  substance  from  which  the 
element  was  flrst  obtained. 

Silicon 

Si 

From  silex,  Latin  for  Jiint,  which  is  nearly 
all  silica  (an  oxide  of  silicon). 

Lithium 

L 

From  (litheios)  stony,  in  allusion 

to  its  supposed  existence  in  the  mineral 
kingdom  only. 

This  name  is  commemorative  of  Stron- 
tian,  a mining  village  in  Argyleshire,  Scot- 
land, in  the  neighborhood  of  which  the 
mineral  known  as  strontianite  or  carbonate 
of  strontium  was  first  found. 

Strontium  

Sr 

Cerium  

Ce 

Discovered  in  1803,  and  named  after  the 
planet  Ceres,  which  was  discovered  on  Jan. 
1,  1801.  The  oxalate,  CeC204, 311^0,  is  offi- 
cial, but  seldom  used. 

Chromium 

Cr 

From  XPftJ.wa  (chioma)  color,  in  allusion 
to  the  characteristic  appearance  of  its  salts. 

Manganese 

Mil 

Probably  a mere  transposition  and  re- 
petition of  most  of  the  letters  of  the  word 
magnesia,  with  whose  compounds  those  of 
manganese  were  confounded  till  the  year 
1740. 

Cobalt ; 

Co 

Cobalus  or  Kobold  was  the  name  of  a de- 
mon supposed  to  inhabit  the  mines  of  Ger- 
many. The  ores  of  cobalt  were  formerly 
troublesome  to  the  German  miners,  and 
hence  received  the  name  their  metallic 
radical  now  bears. 

Nickel 

Ni 

Nickel,  from  nil,  is  a popular  German 
term  for  worthless.  The  mineral  now  known 
as  nickel  ore  was  formerly  called  by  the 
Germans  Kiipfernickel,  false  copper,  on  ac- 
count of  its  resemblance  to  copper  {Kupfer) 
ore.  When  a new  metallic  element  was 

- 

found  in  the  ore,  tlie  name  nickel  was  re- 
tained. 

Tin  (Stannum)... 

Sn 

Both  words  are  possibly  corruptions  of 
the  old  British  word  staen,  or  the  Saxon 
word  Stan,  a stone.  Tin  was  first  discovered 
in  Cornwall,  and  the  ore  (an  oxide)  is  called 
tinstone  to  the  present  day. 

THE  ELEMENTS,  THEIR  SYMBOLS,  ETC.  31 


Name. 

Symbol. 

Derivation  of  Name. 

Gold  (Aurum)  ... 

Au 

Aurum  (Latin)  from  a Hebrew  word  sig- 
nifying the  color  of  fire. 

Gold,  an  old  Saxon  word  expressive  of 
yellow,  the  color  of  this  metal 

Platinum 

Pt 

From  platina  (Spanish),  diminutive  of 
plata,  silver,  in  allusion  to  its  inferiority  in 
lustre,  but  otherwise  general  resemblance 
to  silver. 

Bismuth 

Bi 

Slightly  altered  from  the  German  TL’s- 
muth,  derived  from  Wiesematte  “ a beauti- 
ful meadow,”  a name  given  to  it  originally 
by  the  old  miners  in  allusion  to  the  prettily 
variegated  tints  presented  by  the  freshly 
exposed  surface  of  this  crystalline  metal. 

Cadmium 

Cd 

(Kadmeia)  was  the  ancient  name 
of  calamine  (carbonate  of  zinc),  with  which 
carbonate  of  cadmium  was  long  confounded, 
the  two  often  occurring  together. 

Gold,  Platinum,  Tin,  and  Silicon  are  classed  with  the  less  impor- 
tant elements,  because  their  salts  are  seldom  used  in  pharmacy. 

It  will  be  noticed  that  the  symbol  of  an  element  is  simply  the  first 
letter  of  its  Latin  name,  which  is  generally  the  same  as  in  the  Eng- 
lish. Where  two  names  begin  with  the  same  letter,  the  less  import- 
ant has  an  additional  letter  added. 


QUESTIONS  AND  EXERCISES. 

1.  Of  how  many  elements  is  terrestrial  matter  composed  ? 

2.  In  what  state  do  the  elements  occur  in  nature  ? 

3.  Distinguish  between  the  art  and  the  science  of  chemistry. 

4.  What  is  the  difference  between  an  element  and  a compound  ? 

5.  Enumerate  the  chief  non-metallic  elements. 

6.  Describe  a process  for  the  preparation  of  oxygen. 

7.  How  are  gases  usually  stored? 

8.  Mention  the  chief  properties  of  oxygen. 

9.  What  is  the  source  of  animal  warmth? 

10.  State  the  proportion  of  oxygen  in  air. 

11.  Is  the  proportion  constant,  and  why  ? 

12.  Give  a method  for  the  elimination  of  hydrogen  from  water. 

13.  State  the  properties  of  hydrogen. 

14.  Why  is  a mixture  of  hydrogen  and  air  explosive  ? 

15.  Explain  the  effects  producible  by  the  ignition  of  large  quanti- 
ties of  coal-gas  and  air. 

16.  What  is  the  nature  of  combustion? 

17.  Define  a combustible  and  a supporter  of  combustion. 


32 


GENERAL  PRINCIPLES  OF 


18.  Describe  the  structure  of  flame. 

19.  State  the  principle  of  the  Davy  safety-lamp. 

20.  To  what  extent  is  hydrogen  lighter  than  oxygen? 

21.  What  do  you  mean  by  diffusion  of  gases  ? 

22.  State  Graham’s  law  concerning  diffusion. 

23.  Name  the  source  of  phosphorus,  and  give  its  characters. 

24.  Why  does  phosphorus  burn  in  air  ? 

25.  What  remains  when  ignited  phosphorus  has  removed  all  the 
oxygen  from  a confined  portion  of  air  ? 

26.  Mention  the  properties  of  nitrogen. 

27.  What  office  is  fulfilled  by  the  nitrogen  of  air? 

28.  State  the  proportions  of  the  chief  constituents  of  air. 

29.  Mention  the  minor  or  occasional  constituents  of  air. 

30.  What  is  the  proportion  by  weight  of  nitrogen  to  oxygen  in  the 
atmosphere  ? 

31.  Give  the  specific  gravity  of  nitrogen. 

32.  How  is  chlorine  prepared? 

33.  Enumerate  the  properties  of  chlorine. 

34.  Define  the  terms  deodorizer  and  disinfectant, 

35.  Explain  the  bleaching  effect  of  chlorine. 

36.  What  proportion  of  hydrogen  to  chlorine  is  necessary  for  the 
formation  of  hydrochloric  acid  gas  ? 

37.  State  the  prominent  physical  and  chemical  characters  of  sul- 
jihur. 

38.  State  the  prominent  characters  of  carbon. 

39.  State  the  prominent  characters  of  iodine. 

40.  Give  the  derivations  of  the  names  of  some  of  the  elements. 

41.  What  are  the  symbols  of  oxygen,  hydrogen,  nitrogen,  carbon, 
chlorine,  iodine,  sulphur,  phosphorus  ? 


The  Learner  is  recommended  to  read  the  following  para- 
graphs ON  THE  General  Principles  of  Chemical  Philosophy 

CAREFULLY  ONCE  OR  TWICE,  THEN  TO  STUDY  (EXPERIMENTALLY,  IF 
possible)  the  SUCCEEDING  PAGES,  RETURNING  TO  AND  READING  OVER 

THE  General  Principles  from  time  to  time  until  they  are 

THOROUGHLY  COMPREHENDED. 


THE  GENERAL  PRINCIPLES  OF  CHEMICJlL 
PHILOSOPHY. 


Definition  of  Chemical  Action. 

The  learner  may  now  proceed  to  study  the  manner  in  which  sub- 
stances act  chemically  on  each  other.  Ry  acting  chemically  it  will 
be  obvious,  from  the  preceding  experiments,  that  what  is  meant  is 
so  affecting  each  other  that  the  substances  are  greatly  altered  in 
properties.  A mixture  of  oxygen  and  hydrogen  is  still  a gas ; a 
chemical  compound  of  oxygen  and  hydrogen  is  a licpiid,  namely 


CHEMICAL  PHILOSOPHY. 


33 


water.  Iodine  is  only  slightly  soluble  in  water,  and  forms  a brown- 
colored  solution,  and  iron  is  insoluble ; but  when  iodine  and  iron  are 
chemically  combined  the  product  is  very  soluble  in  water,  forming  a 
light-green  solution  in  which  the  eye  can  detect  neither  iodine  nor 
iron,  and  which  is  utterly  unlike  iron  or  iodine  in  any  one  of  their 
properties.  Sand,  sugar,  and  butter  rubbed  together  form  a mere 
mixture,  from  which  water  would  extract  the  sugar,  and  ether  dis- 
solve out  the  butter,  leaving  the  sand.  Tartaric  acid,  carbonate  of 
sodium,  and  water  added  to  each  other  form  a chemical  compound 
containing  neither  tartaric  acid,  nor  carbonate  of  sodium,  these  bodies 
having  attacked  each  other  and  formed  fresh  combinations.  Either 
of  these  illustrations  shows  that  chemical  action  is  distinguished 
from  all  other  actions  by  producing  an  entire  change  of  properties  in 
the  bodies  on  which  it  is  exerted.  Chemical  action  is  further  distin- 
guished by  the  fact  that  it  only  takes  place  between  definite  weights 
and  volumes  of  matter;  a subject  that  will  be  more  fully  discussed 
immediately. 

Atoms. 

In  a chemical  compound  what  has  become  of  the  constituents? 
Let  the  reader  place  before  him  specimens  of  sulphur,  iron,  and  sul- 
phide of  iron ; or  iodine,  iron,  solid  iodide  of  iron  and  its  solution  in 
water  or  syrup  [Syrupus  Ferri  lodidi,  B.  P.  and  U.  S.  P.).  In  the 
sulphide  of  iron  what  has  become  of  the  sulphur  and  of  the  iron  from 
which  it  was  made  ? The  mixture  of  sulphur  and  iron  in  combining 
to  form  sulphide  of  iron  has  not  lost  weight,  and,  indeed,  by  certain 
processes  it  is  possible  to  recover  its  sulphur  as  sulphur,  and  its  iron  as 
iron  ; so  that  we  are  compelled  to  believe,  we  cannot  avoid  the  conclu- 
sion, that  sulphide  of  iron  contains  particles  of  sulphur  and  of  iron.  But 
how  small  must  be  those  particles ! Bub  a minute  fragment  to  dust 
in  a mortar  and  place  a trace  of  the  powder  under  the  highest  power 
of  the  best  microscope ; no  yellow  particle  is  visible,  not  the  minutest 
portion  of  lustrous  metal,  but  dull-brown  miniature  fragments  of  the 
original  mass.  The  elementary  particles  of  sulphur  and  iron,  or  of 
the  elements  in  any  other  compound  (the  chlorine  and  sodium  in 
common  salt  or  the  iodine  and  iron  in  solution  of  iodide  of  iron),  are, 
in  short,  too  small  to  be  seen.  Can  they  be  imagined?  Again,  no. 
The  mind  cannot  conceive  of  a particle  of  anything  (sulphur,  iron, 
sulphide  of  iron,  or  what  not)  so  small  but  what  the  next  instant  the 
imagination  has  divided  it.  Yet  learner  and  teacher  must  have  some 
common  platform  on  which  to  reason  and  converse.  The  difficulty 
is  met  by  speaking  of  these  inconceivably  small  particles  as  atoms 
[atofio^,  atomos,  indivisible ; from  the  privative  a and  tsiA.vco,  temno, 
to  cut — that  which  cannot  be  cut,  or  divided)  an  expedient  suggested 
by  our  countryman  Dalton  at  the  commencement  of  the  present 
century.  It  is  a somewhat  unsatisfactory  expedient,  no  doubt,  but 
the  only  one  possible  to  the  majority  of  minds  in  the  present  state  of 
knowledge  and  education.  We  cannot  speak  of  iodine  and  iron 
uniting  lump  to  lump,  as  two  bricks  are  cemented  together  or  blocks 
of  wood  glued  together,  for  such  is  not  the  kind  of  action.  We 
cannot  select  a minute  fragment  of  each  to  regard  as  the  combining 


34 


GENERAL  PRINCIPLES  OF 


portions,  for  the  minutest  fragment  we  could  obtain  is  visible,  and 
iodide  of  iron  contains  neither  visible  iodide  nor  visible  irou.  And 
yet  iodide  of  iron  contains  both  iodine  and  iron,  or,  at  least,  a given 
weight  of  the  compound  is  obtained  from  the  same  weight  of  con- 
stituents, and  the  same  weight  of  constituents  is  obtainable  from  an 
equal  weight  of  the  compound.  We  might  say  that  molecules  are 
concerned  in  the  operation,  but  molecules  means  little  masses  of — of 
what?  there  is  positively  no  word  left  with  which  to  carry  on  con- 
versation and  description  but  atoms.  Any  other  mode  of  treating 
the  matter  is  too  subjective  for  general  employment.  Moreover  any 
difficulty  in  forming  a definite  conception  of  an  atom  concerns  the 
student  of  physics  rather  than  of  chemistry,  the  chemist  regarding 
an  atom  as,  in  the  words  of  Kekule,  “ a particle  of  matter  which 
undergoes  no  further  division  in  chemical  metamorphoses^^ 

The  Chemical  Force. 

What  power  binds  the  atoms  of  a chemical  compound  together  in 
such  marvellous  closeness  of  union  that  in  the  couple  or  group  they 
lose  all  individuality?  Clearly  an  attractive  force  of  enormous 
power,  a force  remotely  resembling,  perhaps,  that  which  attracts  a 
piece  of  iron  to  a magnet.  Only  by  such  an  assumption  can  we  con- 
ceive that  common  salt  contains  chlorine  and  a metal  (sodium),  or 
that  wood  contains  carbon,  hydrogen,  and  oxygen.  Were  not  this 
force  thus  all-powerful  the  carbon  in  wood  would  show  its  blackness 
and  other  qualities,  and  the  hydrogen  and  oxygen  give  indications  of 
their  gaseous  and  other  characters.  This  attractive  force  is  com- 
monly termed  the  chemical  force,  sometimes  chemical  affinity.  The 
word  chemism  has  also  been  proposed  for  it,  just  as  the  magnetic 
force  is  termed  magnetism,  but  has  not  been  generally  adopted. 

Molecules. 

A single,  free,  uncombined  atom  cannot  exist  in  a state  of  isola- 
tion for  any  appreciable  length  of  time.  For  an  atom  is  the  home  of 
an  attractive  force  of  great  intensity,  and  the  moment  it  is  liberated 
from  a state  of  combination  (hydrogen  from  water  for  instance,  or 
chlorine  from  salt)  finds  itself  in  proximity  to  another  atom  having 
similar  desires  for  union,  so  to  speak ; the  result  is  an  impetuous 
rushing  together  and  formation  of  either  couples,  trios,  or  groups, 
according  to  the  nature  of  the  atoms.  It  would  be  as  difficult  to  con- 
ceive of  separate  atoms  as  to  imagine  that  a strong  magnet  and  a 
piece  of  steel  could  be  suspended  close  to  each  other  without  being 
drawn  together.  These  pairs  and  other  groups  of  atoms  are  conve- 
niently designated  by  the  one  word  molecule,  the  diminutive  of  mole, 
a mass ; literally,  little  masses.  Dissimilar  kinds  of  atoms  seem  to 
have  greater  attraction  for  each  other  than  similar  kinds  ; for,  first, 
the  masses  of  matter  met  with  in  nature  in  the  great  majority  of 
cases  contain  two  or  more  dissimilar  elements ; and,  secondly,  at  the 
moment  certain  elements  are  liberated  from  their  combination,  they 
are  far  more  active  towards  other  elements  than  afterwards,  when 
the  atoms  have  probably  united  to  form  molecules. 


CHEMICAL  PHILOSOPHY. 


35 


Eecapitulation. 

It  is  desirable  that  the  learner  should  here  make  some  experiment 
which  will  serve  to  bring  again  under  notice  in  an  applied  form  what 
has  just  been  stated  respecting  the  substances  termed  chemical  com- 
pounds, and  concerning  the  character  of  that  chemical  force  which 
resides  in  the  atoms  of  molecules.  The  following  will  usefully  serve 
this  purpose ; it  is  the  process  for  detecting  a trace  of  sulphurous 
acid  in  common  liquid  hydrochloric  acid. 

As  already  proved,  hydrogen  gas  and  chlorine  gas,  when 
united,  form  hydrochloric  acid  gas  : the  latter  dissolved  in 
water  is  the  ordinary  liquid  of  the  shops  termed  Hydro- 
chloric Acid^  the  Acidum  Hydrochloricum  of  Pharmaco- 
poeias. Commercial  samples  of  this  liquid  not  unfrequently 
contain  as  an  impurity  a trace  of  sulphurous  acid  gas,  a 
body  also  already  mentioned  and  experimentally  prepared 
— a trace  too  small  to  be  detected  by  its  odor.  Obtain  a 
specimen  of  common  liquid  hydrochloric  acid  containing 
as  an  impurity  a trace  of  sulphurous  acid,  or  adopt  the 
more  simple  course  of  purposely  adding  a few  drops  of 
aqueous  solution  of  sulphurous  acid  {Acidum  Sulphuro- 
sumf^  B.  P.)  to  some  h^^drochloric  acid.  (If  no  sulphur- 
ous acid  is  at  hand,  the  object  may  be  accomplished  by 
pouring  a quarter  or  half  an  ounce  of  liquid  hydrochloric 
acid  into  a wide-mouthed  bottle,  then  burning  a fragment 
of  sulphur  on  a wire  or  strip  of  wood  inside  the  bottle  for 
a few  seconds,  and  shaking  the  gas  and  liquid  together.) 
Pour  some  of  the  impure  liquid  hydrochloric  acid  into  a 
test-tube,  add  about  an  equal  bulk  of  water,  and  then  drop 
in  some  fragments  of  the  metal  zinc.  Effervescence  will 
occur,  due  to  the  escape  of  inodorous  hydrogen  gas,  to- 
gether with  a small  quantity  of  another  badly-smelling  gas 
termed  sulphuretted  hydrogen  gas.  Bring  the  mouth  of 
the  tube  under  the  nose ; the  presence  of  sulphuretted  hy- 
drogen will  at  once  be  recognized. 

The  hydrochloric  acid  has  now  been  tested  for  sulphurous  acid.  If 
the  experiment  be  performed  on  any  commercial  specimen  of  the 
acid,  and  a smell  of  sulphuretted  hydrogen/be  observed,  the  operator 
would  at  once  be  able  to  state  that  the  specimen  contains  sulphurous 
acid  as  an  impurity. 

The  true  explanation  of  what  occurs  in  the  successive  steps  of  the 
foregoing  experiment  is  as  follows : — 

Hydrochloric  acid  is  a chemical  compound  of  hydrogen  and  chlo- 

* These  aqueous  solutions  of  acids  are  generally,  for  the  sake  of 
brevity,  simply  termed  acids. 


36 


GENERAL  PRINCIPLES  OP 


rine.  That  it  is  a chemical  compound,  and  not  a mere  mechanical 
mixture  of  hydrogen  and  chlorine,  is  shown  by  the  fact  that  its  pro- 
perties are  altogether  different  from  the  properties  of  its  constituents. 
The  attractive  power  or  chemical  force  resident  in  the  atoms  of 
chlorine  and  of  hydrogen  have  caused  them  to  combine  in  the  closest 
manner  imaginable  and  form  pairs  of  atoms  or  molecules  of  the 
chemical  compound — hydrochloric  acid.  Zinc  being  introduced  into 
the  acid,  and  the  atoms  of  zinc  and  chlorine  having,  as  a matter  of 
fact,  even  still  greater  attraction  for  each  other  than  the  hydrogen 
for  the  chlorine,  the  zinc  and  chlorine  atoms  combine  and  form  a new 
molecule  (termed  chloride  of  zinc)  which  remains  in  the  liquid,  while 
the  hydrogen  atoms,  having  the  atoms  of  no  other  element  to  combine 
with,  if  the  acid  is  pure,  unite  to  form  pairs,  or  molecules  of  hydro- 
gen, and  in  that  state  escape  from  the  vessel.  If  the  acid  be  impure 
from  the  presence  of  sulphurous  acid  (sulphurous  acid  gas,  it  will  be 
remembered,  is  a compound  of  sulphur  and  oxygen),  some  of  the  hy- 
drogen atoms,  at  the  moment  of  their  birth,  their  nascent  state 
(from  nascor,  to  be  born),  finding  the  atoms  of  other  elements  pre- 
sent, namely,  the  atoms  of  sulphur  and  o:?s^ygen  of  the  sulphurous 
acid,  combine  by  preference  with  these  atoms  and  form  new  mole- 
cules, the  sulphur  and  hydrogen  forming  sulphuretted  hydrogen,  and 
the  oxygen  and  hydrogen  producing  water : the  former  escapes  with 
the  great  bulk  of  the  hydrogen,  while  the  water  remains  with  the 
water  already  in  the  vessels. 


Conditions  and  nature  of  the  manifestation  of  the  Chemical 

Force. 


The  exertion  of  chemical  affinity  is  only  possible  when  substances 
are  in  close  contact.  Thus  it  was  necessary  to  bring  the  oxygen, 
hydrogen,  phosphorus,  chlorine,  sulphur,  carbon,  iodine,  and  iron  into 
intimate  contact  before  reaction  occurred.  The  exact  nature  of  these 
actions,  as  indeed  of  all  in  which  substances  act  chemically,  would 
seem  to  be  an  interchange,  most  generally  a mutual  one,  of  the  atoms 
of  which  the  molecules  consist — a change  of  partners,  so  to  speak. 
Thus  in  the  experiment  in  which  hydrogen  and  chlorine  gases  united 
to  form  hydrochloric  acid  gas,  a pair  of  atoms  in  a hydrogen  mole- 
cule, and  a pair  of  atoms  in  a chlorine  molecule,  finding  themselves 
opposite  to  each  other,  re-paired  with  each  other,  the  atoms  of  each 
of  the  old  molecules  unlinking,  so  to  say,  and  pairing  off  in  fresh 
couples — as  two  brothers  who  for  many  years  have  been  close  com- 
panions, and  two  sisters  similarly  united,  thrown  freshly  into  each 
other’s  society  soon  accept  new  and  still  more  congenial  couplement. 


Hydrogen  , Chlorine 
Hydrogen  Chlorine 


become 


Hydrogen  , Hydrogen 

Chlorine  ^ Chlorine. 


Or,  using  the  symbols  of  these  elements  instead  of  the  full  names, 


H H and  Cl  Cl  become  H Cl  and  H Cl. 


Still  further  economizing  space  and  trouble,  the  same  statement  may 
be  made  in  the  following  form : 

H2  and  CI2  become  2HC1. 


CHEMICAL  PHILOSOPHY. 


SI 


Once  more,  by  using  the  plus  sign  (+)  instead  of  the  words  “and” 
or  “ added  to,”  and  the  sign  or  symbol  = or  equal  instead  of  the 
words  “ become”  or  “ are  equal  to,”  we  reach  the  shortest  method  of 
expressing  this  chemical  action  : — 

H,  + CI2  = 2HC1. 

This  is  the  form  in  which  such  an  action  may  be  expressed  in  the 
student’s  note-book.  It  is  the  shortest  and  most  convenient  form, 
and  is  instructive  and  suggestive  to  the  mind. 

Chemical  Notation. 

We  have  thus  gradually  arrived  at  a spot  in  the  path  of  chemical 
philosophy  at  which  we  must  halt  to  more  fully  discuss  the  usual 
method  of  recording  chemical  travels.  We  have  arrived  at  the  sub- 
ject of  chemical  notation  (from  noto,  to  mark),  the  art  or  practice 
of  recording  chemical  facts  by  short  marks,  letters,  numbers,  or  other 
signs.  Already  the  first  capital  letter,  or  the  first  and  one  of  the 
following  small  letters  of  the  Latin  names  of  the  elements  have  been 
employed  as  contractions,  or  short-hand  expressions,  or  symbols  of 
the  whole  name.  Thus  H has  been  used  for  the  word  “hydrogen,” 
and  Cl  for  “ chlorine.”  A second  function  of  such  a symbol  is  that 
of  indicating  one  atom.  Thus  H stands  not  only  for  the  word  or 
substance  “hydrogen,”  but  for  one  atom  of  hydrogen.  Large  and 
small  figures  (2  or  2)  indicate  a corresponding  number  of  atoms,  the 
small  figure  only  multiplying  the  one  particular  symbol  to  which  it 
is  attached,  while  a larger  figure  multiplies  all  the  symbols  it  pre- 
cedes. Thus  H2  means  two  atoms  of  hydrogen,  and  CI2  two  atoms 
of  chlorine  ; while  2HC1  means  two  atoms  of  hydrogen  and  two  atoms 
of  chlorine,  or,  in  one  word,  two  molecules  of  hydrochloric  acid  gas. 
A third  function  of  such  a symbol  as  H or  Cl  is  that  of  indicating 
one  volume  of  the  element  in  the  gaseous  state.  Thus  H,  Cl,  or  0 
stand,  first,  for  the  substances  named  hydrogen,  chlorine,  and  oxygen  ; 
secondly,  for  single  atoms  of  hydrogen,  chlorine,  and  oxygen;  and 
thirdly,  for  single  and  equal  volumes  (be  they . gallons,  pints,  or 
minims)  of  chlorine,  hydrogen,  and  oxygen.  It  will  be  remembered 
that  one  test-tubeful  of  hydrogen  and  an  equal  sized  test-tubeful  of 
chlorine  were  employed  in  forming  hydrochloric  acid  gas,  HCl. 

The  position  of  symbols  tells  for  something.  Thus  HCl  indicates 
not  only  the  substances  hydrogen  and  chlorine,  single  atoms  of  each 
of  the  substances,  and  equal  volumes  of  each,  but  also  that  the  two 
substances  are  joined  together  by  the  chemical  force.  If  the  two 
letters  were  placed  one  under  the  other,  or  at  some  distance  apart, 
or  were  separated  by  a comma  or  a plus  sign  (-j-),  they  would  be 
understood  to  mean  a mere  mixture  of  the  elements ; but  placed  as 
close  as  the  printer’s  types  will  conveniently  and  consistently  allow, 
they  must  be  considered  to  stand  for  a compound  of  the  elements, 
that  is  to  say,  hydrochloric  acid  gas  (HCl).  The  collection  of  sym- 
bols representing  a molecule  is  termed  formula.  H2,  CI2,  and  HCl 
are  the  formulce  of  hydrogen,  chlorine,  and  hydrochloric  acid  gas, 
H2+  Cl2  = 2HCL 


4 


38 


GENERAL  PRINCIPLES  OF 


Such  a set  of  letters,  figures,  and  marks  as  those  on  the  above  line 
are  collectively  termed  an  equation,  because  indicating  the  equality 
of  the  number  and  nature  of  the  atoms  before'  and  after  chemical 
action.  On  the  left-hand  of  the  sign  of  equality  are  shown  two 
molecules,  and  on  the  right-hand  two  molecules  ; but,  of  the  mole- 
cules on  the  left,  one  contains  two  atoms  of  hydrogen  and  the  other 
two  atoms  of  chlorine,  while  of  the  molecules  on  the  right  each  con- 
tains one  atom  of  hydrogen  and  one  of  chlorine.  The  equation  forms 
a short  and  convenient  plan  of  recording  the  facts  of  experiment. 

Instead  of  an  equation,  a diagram  may  be  employed  to  exhibit 
the  same  facts.  Thus  : 


HOT 


HCl 


Eelation  of  Gases  to  Liquids  and  Solids. 


The  molecules  of  a gas  are  not  close  together,  for  a quantity  of  gas 
may  be  compressed  with  very  little  force  to  half  or  one-fourth  its  bulk, 
in  short  to  such  an  extent  that  in  many  cases  the  molecules  sufficiently 
approximate  to  form  a liquid.  Moreover  from  recent  researches  there 
would  seem  to  be  no  sharp  line  of  demarcation  between  the  gaseous 
and  liquid  condition  of  a substance  (Andrews).  In  a liquid  the 
molecules  are  still  free  to  glide  about  with  ease  amongst  each  other ; 
and  though  in  solids  they  exhibit  less  mobility,  still  even  solids  may 
be  compressed  by  powerful  pressure,  so  that  probably  in  no  instance 
are  molecules  in  absolute  contact.  Why  a gas  under  pressure  should 
immediately  return  to  its  original  bulk  when  the  pressure  is  removed, 
while  a liquefied  or  solidified  gas  only  slowly  resumes  the  'gaseous  or 
vaporous  state,  is  a question  which  requires  for  discussion  a knowl- 
edge of  the  nature  of  forces  other  than  the  chemical : here  chemistry 
joins  the  domain  of  physics.  It  was  necessary,  however,  to  state 
thus  much  respecting  the  condition  of  the  molecules  of  a gas  in  order 
that  the  learner  might  be  prepared  for  the  fact,  that  mixtures  of 
certain  gaseous  elements,  in  combining  to  form  gaseous  compounds, 
diminish  considerably  in  volume.  Thus,  w^hile  a pint  of  hydrogen 
and  a pint  of  chlorine  give  a quart  of  hydrochloric  acid  gas,  two 
pints  of  hydrogen  and  one  of  oxygen  are  necessary  to  produce  a 
quart  of  gaseous  water  (steam).  It  will  be  remembered  that  two 
volumes  of  hydrogen  and  one  of  oxygen  were  necessary  in  a previous 
experiment  in  which  water  was  formed.  With  regard  to  the  nota- 
tion of  the  matter,  it  will  be  sufficient  to  state  here  that  while  a 
symbol  represents  one  volume  of  any  gas,  a formxda  of  any  gas  or 
vapor  represents  two  volumes.  I^y  remembering  this  general  rule 
we  may,  by  looking  at  a formula,  tell  how  many  volumes  of  constitu- 
ents were  concerned  in  the  formation  of  a compound,  and  therefore 
w'hat  amount  of  condensation,  if  any,  occurred  during  the  act  of 


CHEMICAL  PHILOSOPHY. 


39 


formation.  By  thus  reading  and  interpreting  the  formula  for  water, 
11,0,  we  see  that  two  volumes  of  steam  (at  any  temperature)  may 
be  obtained  from  two  volumes  of  hydrogen  and  one  volume  of  oxygen 
(at  the  same  temperature)  and  thus  that  the  extent  of  condensation 
when  hydrogen  and  oxygen  (at  a stated  temperature)  unite  to  form 
gaseous  water  (at  the  same  temperature)  is  from  three  to  two.  This 
subject  will  again  be  treated  of  in  connection  with  those  of  Chemical 
Combination  and  Specific  Gravity  of  Gases. 

Further  Eemarks  on  Chemical  Notation. 

We  may  now  take  the  experiment  just  alluded  to  as  an  additional 
example  of  chemical  action,  and  the  best  and  simplest  way  of  ex- 
pressing the  same  by  notation.  When  two  volumes  of  hydrogen 
and  one  of  oxygen  were  caused  to  combine,  the  production  of  flame 
and  noise  proved  that  chemical  action  of  some  kind  had  taken  place  ; 
had  the  experiment  been  performed  in  dry  vessels,  evidence  of  the 
precise  action  would  have  been  found  in  the  bedewment  or  moisture 
produced  by  the  condensation  of  the  water  on  the  sides  of  the  tube. 
Similar  evidence  was  afforded  on  holding  a cool  glass  surface  over 
the  hydrogen-flame.  The  action  is  expressed  in  the  following  equa- 
tion : — 

+ 0,  = 2H,0. 

Instead  of  an  equation,  the  following  diagram  may  be  employed : — 


The  foregoing  aggregation  of  symbols  or  short-hand  characters,  or 
formula,  11,0,  is,  then,  a convenient  picture  of  the  facts  that  have 
already  come  before  us,  viz.,  that  water  is  formed  of  the  elements 
hydrogen,  H,  and  oxygen,  0 ; moreover,  that  it  is  formed  of  two 
measures  or  volumes  of  hydrogen,  H,,  to  one  of  oxygen,  0 ; and, 
thirdly,  that  the  molecule  of  water  (H,0)  is  formed  of  two  atoms  of 
hydrogen  (H,)  and  one  of  oxygen  (0).  The  formula  also  fulfils  the 
fourth  function  of  indicating  that  the  two  volumes  of  hydrogen  and 
one  of  oxygen  in  combining  condensed  to  two  volumes  of  steam. 
That  the  resulting  bulk  of  steam  afterwards  shrunk  most  considerably 
in  condensing  to  water  is  another  matter  altogether,  a physical  and 
not  a chemical  result,  and  due  to  the  approximation  of  the  molecules 
of  water  after  formation. 

Another  experiment  already  performed,  illustrating  the  character 
of  the  manifestations  of  chemical  force,  and  its  symbolic  expression, 
was  that  in  which  the  red-hot  carbon  of  wood  was  plunged  into 
oxygen.  The  evidence  of  chemical  action  in  that  case  was  the  sudden 
inflammation  of  the  carbonaceous  extremity  of  the  wood.  The  par- 
ticles of  carbon  and  oxygen,  having  intense  attraction  or  affinity  for 


40 


GENERAL  PRINCIPLES  OF 


each  other  at  that  temperature,  rushed  together  so  impetuously  as 
suddenly  to  produce  a large  additional  quantity  of  heat,  an  amount 
sufficient  to  cause  the  particles  to  emit  an  intense  white  light.  The 
action  between  carbon  and  oxygen  is  expressed  on  paper  in  either 
of  the  following  ways: — 

C,  + 20^  = 2CO, 

0.{g 
{§: 

CO2  is  the  formula  of  the  well-known  gaseous  body  commonly  termed 
carbonic  acid  gas. 

The  reader  should  here  draw  for  himself  equations  or 
diagrams  similar  to  the  three  just  given,  and  thus  show 
the  formation  of  the  three  bodies  he  has  already  produced 
— namely,  phosphoric  anh^^dride  sulphurous  acid 

gas  (SO2),  and  iodide  of  iron  (Fel2),  submitting,  the  same, 
if  possible,  to  a tutor  or  other  authority  to  assure  himself 
of  their  correctness. 

Note. — In  the  foregoing  experiments  several  illustrations  occur  of 
the  formation  of  compounds  having  the  gaseous,  liquid,  and  solid 
conditions,  in  one  of  which  three  forms  all  matter  in  the  universe 
exists. 


Laws  of  Chemical  Combination  (by  Weight). 

Chemistry  as  a science  is  little  more  than  a hundred  years  old, 
though  very  many  of  the  facts  and  operations  we  now  term  chemical 
have  been  known  as  isolated  items  of  knowledge  for  centuries.  Thus, 
the  ancient  Egyptians  made  glass,  vitriol,  soap,  and  vinegar ; and  the 
Greeks  started  the  idea  that  matter  was  composed  of  a few  elements, 
imagining  earth,  air,  fire,  and  w^ater  to  be  elements.  But  the  great 
general  principles  which  interlace  and  bind  together  separate  facts, 
those  which  from  their  extensive  application  and  importance  are  de- 
nominated laws,  have  all  been  brought  to  light  since  the  year  1770. 
Between  1785  and  1800,  Bryan  Higgins,  William  Higgins,  Wenzel, 
Richter,  and  Proust  made  analyses  and  researches  which  led  up  to 
the  following  generalizations:  When  comp02inds  finite  to  form  de- 
finite  chemical  substances,  they  always  combine  in  the  same  propor- 
tions. The  curious  character  of  this  fact  could  but  be  most  striking, 
and  indeed  is  so  now,  to  the  mind  receiving  it  for  the  first  time.  Thus 
w’ater  added  to  quicklime  gives  slaked  lime,  a perfectly  definite 
chemical  substance.  But  whereas  sand  and  water,  sugar  and  water, 
sand  and  sugar,  and  such  mixtures  may  be  obtained  by  adding  to- 
gether the  ingredients  in  any  proportions  whatever,  say,  90  of  sugar 


CHEMICAL  PHILOSOPHY. 


41 


and  10  of  sand,  or  10  of  sugar  and  90  of  sand,  slaked  lime  invariably 
results  from  the  combination  of  75 J of  quicklime  and  24i  of  water. 
If  a larger  proportion  than  75f  per  cent,  of  quicklime  be  employed, 
the  excess  remains  as  quicklime  mixed  with  the  slaked  lime ; and  if 
more  than  24i  per  cent,  of  water  be  used,  an  excess  of  water  remains 
with  the  slaked  lime  and  evaporates  if  the  mixture  be  exposed  to 
the  air.  Dalton  discovered  that  when  elements  unite  to  form  a de- 
finite substance,  they,  like  compounds,  always  combine  in  the  same 
proportions ; and  he  was  the  first  to  set  forth  the  law  in  a clear 
manner. 

First  Law  of  Chemical  Combination. 

A definite  compound  always  contains  the  same  elements 
in  the  same  proportions. 

Thus  common  salt  always  contains  39^  per  cent,  of  the  metal  so- 
dium to  60 1 of  chlorine,  and  water  always  89  of  oxygen  to  11  per 
cent,  of  hydrogen  (more  exactly  88.89  to  11.11).  As  with  the  quick- 
lime and  water,  so  with  the  chlorine  and  sodium,  and  the  constitu- 
ents of  many  other  chemical  compounds  ; in  such  cases  if  either  be 
added  to  the  other  in  any  quantity  beyond  stated  proportions,  the 
excess  plays  no  part  whatever  in  the  act  of  combination.  (In  some 
eases,  as  will  be  seen  directly,  excess  of  either  plays  a very  simple 
but  very  remarkable  part.)  In  short,  whether  a compound  be  made 
directly  from  its  elements,  or  by  the  combination  of  other  compounds, 
or  indirectly  as  one  of  two  products  of  the  action  of  substances  chem- 
ically on  each  other,  whatever  be  its  origin,  if  it  is  a definite  com- 
pound it  always  contains  the  same  elements  in  the  same  proportions. 

Dalton  further  made  such  experimental  researches  as  enabled  him 
to  lay  down  a second  great  law.  He  found  that,  while  many  sub- 
stances only  united  chemically  in  one  proportion,  others  combined  in 
two  or  even  more,  and  he  studied  several  such  naturally  related  bodies. 
He  found  that  while  carbonic  oxide  (a  gas  formed  when  charcoal  is 
burned  with  an  insufficient  supply  of  air)  contains  such  a percentage 
of  carbon  and  oxygen  as  is  represented  by  (to  use  the  simplest  fig- 
ures) 3 and  4,  carbonic  acid  (a  gas  formed  when  charcoal  is  burned 
with  excess  of  air)  contains  3 of  carbon  to  exactly  twice  4 of  oxygen. 
He  proved  that  a similar  relation  existed  between  two  compounds  of 
carbon  and  hydrogen,  and  between  a cluster  of  compounds  of  nitro- 
gen and  oxygen.  The  first  of  the  latter,  to  a given  quantity  of  ni- 
trogen, contains  a certain  proportion  of  oxygen ; the  next,  to  the 
same  quantity  of  nitrogen,  had  twice  the  proportion  of  oxygen ; and 
the  others  have  respectively  three,  four,  and  five  times  as  much  oxy- 
gen as  the  first,  the  quantity  of  nitrogen  remaining  the  same  through- 
out. Dalton  thus  generalized  these  facts  : — 


4* 


42 


GENERAL  PRINCIPLES  OF 


Second  Law  of  Chemical  Combination, 

When  two  elements  unite  in  more  than  one  proportion^ 
the  resulting  compounds  contain,,  to  a constant  proportion 
of  one  element,^  simple  multiple  proportions  of  the  other — or 
the  weights  of  the  constituent  elements  hear  some  similar 
simple  relation  to  each  other. 

Thus  carbonic  oxide  gas  is  a definite  compound  always  containing 
fixed  proportions  of  carbon  and  oxygen,  and  carbonic  acid  gas  also  a 
definite  compound  always  containing  fixed  proportions  of  carbon  and 
oxygen.  Both  thus  obey  the  first  law  of  combination.  But  whereas 
carbonic  oxide  contains,  or  may  be  made  from,  30  parts  (ounces, 
grains,  or  other  weights)  of  carbon  and  40  of  oxygen,  carbonic  acid 
contains,  or  may  be  made  from,  30  parts  of  carbon  and  exactly  twice 
40  of  oxygen. 

This  second  law  cannot  but  be  as  striking  as  the  first  when  freshly 
unveiled  to  the  mind.  Sand  and  sugar,  or  any  substances  which  do  not 
act  chemically  on  each  other,  may  be  mixed  in  the  proportions  of  30 
to  40,  30  to  80,  30  to  60,  or  any  other  quantities ; but  if  an  attempt 
be  made  to  burn  30  parts  of  carbon  in  60  of  oxygen,  the  elements 
will  themselves  naturally  assert  their  own  special  combining  powers, 
and  refuse,  so  to  say,  to  unite  in  these  proportions  : the  30  of  carbon 
will  first  combine  with  40  of  oxygen  and  form  70  of  carbonic  oxide, 
and  this  gas,  which,  had  it  the  opportunity,  would  combine  wdth  40 
more  of  oxygen  and  form  carbonic  acid  gas,  finding  only  half  that 
quantity,  namely,  20  of  oxygen  present,  contents  itself  by  one  half 
(that  is  35  of  carbonic  oxide)  accepting  the  20  of  oxygen  and  be- 
coming carbonic  acid  gas,  while  the  other  half  remains  as  carbonic 
oxide.  This  is  a most  wonderful  fact.  Again,  if  30  parts  of  carbon  be 
burnt  in  more  than  80,  say  85,  of  oxygen,  only  80  will  be  used,  the 
other  5 remaining  as  oxygen  merely  mixed  with  the  resulting  car- 
bonic acid  gas.  If  we  attempt  to  burn  30  parts  of  carbon  in  less 
than  40  of  oxygen,  the  oxygen  will  take  up  three-fourths  its  weight 
of  carbon  and  form  carbonic  oxide,  while  the  excess  of  carbon  wdll 
remain  as  carbon. 

Careful  consideration  of  the  foregoing  two  great  la\vs 
has  suggested  an  important  truth  sometimes  termed  The 
Third  Law  of  Chemical  Combination,^  : The  pro- 

portions  in  which  two  elements  unite  with  a third  are  the 
proportions  (or  simple  multiples  or  submultiples  of  the  pro- 
portions) in  which  they  unite  with  each  other.  Thus  oxy- 
gen in  proportions  of  16  unites  with  hydrogen,  and  carbon 
in  proportions  of  12  unites  wdth  hydrogen;  therefore  16 
and  12  are  the  proportions  in  which  oxygen  and  carbon 
'will  unite  with  each  other, 


CHEMICAL  PHILOSOPHY 


43 


The  Atojuic  Theory. 


The  laws  which  Dalton  (1803  to  1808)  so  largely  aided  to  unveil — • 
two  grand  and  wonderful  truths — he  explained  and  correlated  by  a 
simple  and  beautiful  hypothesis.  Dalton  suggested  that  matter  was 
not  infinitely  divisible,  hut  composed  of  minute  particles  or  atoms 
having  am  invariable  character.  In  the  words  of  Wurtz,  “ To  an 
old  and  vague  notion  he  attached  an  exact  meaning  by  supposing 
that  the  atoms  of  each  hind  of  matter  possess  a constant  iveight,- 
and  that  combination  between  two  kinds  of  matter  takes  place  not 
by  penetration  of  their  substance,  but  by  juxtaposition  of  their 
atoms.” 

Thus  under  this  hypothesis,  or  atomic  theory  as  it  is  generally 
termed,  carbonic  oxide  is  a definite  compound  always  containing  the 
same  elements  in  the  same  proportions,  because  each  particle  of  it  is  ^ 
composed  of  an  atom  of  carbon  and  an  atom  of  oxygen  chemically 
united,  the  weights  of  the  atoms  being  in  the  proportion  of  3 and  4, 
that  is,  having  a constant  weight  of  12  and  16,  as  we  now  believe. 

/ Carbonic  acid  gas  is  also  a definite  compound  always  containing  the 
same  elements  in  the  same  proportions,  and  the  proportion  of  oxygen 
is  just  double  that  in  carbonic  oxide,  because  each  particle  of  it  is 
composed  of  an  atom  of  carbon  (weighing  12)  and  two  atoms  of  oxy- 
gen (each  weighing  16). 


Imaginary  pictures  of  molecules  of  carbonic  oxide  gas  and  carbonic  acid  gas* 


Again,  the  facts  that  with  12  of  carbon  oxygen  unites  in  the  pro- 
portion of  16,  or  a multiple  of  16  ; that  with  12  of  carbon  sulphur 
unites  in  the  proportion  of  32,  or  a multiple  of  32  (the  liquid  known 
as  disulphide  of  carbon  is  a chemical  compound  of  12  of  carbon  to 
twice  32  of  sulphur) ; and,  thirdly,  that  oxygen  and  sulphur  unite  in 
proportions  of  16  and  32,  are  at  once  explained  on  the  assumption 
that  these  elements  exist  in  atoms  which  have  the  respective  weights 
mentioned.  Existing  in  indivisible  particles  (atoms)  w^hich  weigh 
16,  12,  and  32,  oxygen,  carbon,  and  sulphur  must  unite  in  indivisible 


weights  of  16,  12,  and  32. 


AtOxMic  Weights. 


AVhat  has  just  been  stated  respecting  two  or  three  elements  is  true 
of  all  the  elements.  It  is  a fact,  that,  when  elements  unite  with  one 

* The  size  of  atom’s,  their  shape,  their  absolute  weight — whether 
or  not  they  are  in  actual  contact — whether  or  not  they  are  fixed  in 
relation  to  each  other,  free  to  move  about  each  other,  or  in  a constant 
state  of  motion — and  whether  or  not  the  chemical  force  actuates  them 
as  the  force  of  gravitation  influences  our  earth  and  moon  and  solar 
systems,  are  matters  of  which  at  present  we  known  nothing.  The 
two  pictures  are  not  intended  to  convey  any  impression  that  the  fol- 
lowing formula  do  not  give  : CO  or  OC,  OCO  or  OOC  or  COO  or  CO2. 


44 


GENERAL  PRINCIPLES  OF 


another  in  the  peculiar  and  intimate  manner  termed  chemical,  they 
do  not  combine  in  the  haphazard  proportions  of  a mere  mixture,  but 
in  one  fixed  and  constant  proportion.  Such  proportions  or  weights 
represent,  according  to  Dalton,  the  weights  of  their  atoms.  Oxygen 
unites  with  other  elements  in  proportions  of  16,  therefore  16  is  the 
w^eight  of  the  atom  of  oxygen.  Chlorine  unites  with  other  elements 
in  proportions  of  35^,  therefore  35^  is  the  atomic  weight  of  chlorine. 
And  for  a similar  reason  the  atomic  weights  of  hydrogen  will  be  1, 
carbon  12,  sulphur  32,  nitrogen  14,  and  iodine  127.  Of  course  it  will 
be  understood  that  these  are  the  relative  weights  of  atoms,  for  we 
cannot  know  the  absolute  weights.  All  that  is  known  is  that  the 
chlorine  atom,  for  instance,  is  35.5  times  as  heavy  as  the  hydrogen 
atom,  whatever  the  absolute  weight  of  the  latter  may  be,  and  the 
iodine  atom  127  times  as  heavy.  The  quantity  of  metal  which  with 
35.5  of  chlorine  will  form  a chloride,  and  with  twice  35.5  a second 
chloride  (dichloride  or  bichloride),  will  require  127  of  iodine  to  form 
an  iodide,  and  twice  127  of  iodine  to  form  a second  iodide  (a  diniodide 
or  biniodide).* 

Laws  of  Chemical  Combination  (by  Volume). 

In  1809  Gay-Lussac  showed  it  to  be  a fact  that  when  gaseous  ele- 
ments unite  with  one  another  in  the  intimate  manner  termed  chemical, 
they  do  not  combine  in  the  haphazard  proportions  (that  is,  propor- 
tions by  measure  or  volume)  of  a mere  mixture,  but  in  constant  pro- 
portions in  the  case  of  any  single  definite  compound,  and  in  simple 
multiple  proportions  in  cases  where  two  elements  form  more  than  one 
definite  compound.  He  thus  proved  that  the  laws  respecting  the 
constancy  of  weight  with  which  elements  combine  hold  good  with 
reference  to  volume,  at  all  events  in  those  cases  in  which  elements 
exist  in  or  can  be  made  to  assume  the  gaseous  condition.  A volume 
of  hydrogen  gas  and  an  equal  one  of  chlorine  gas  give  hydrochloric 
acid  gas.  Two  volumes  of  hydrogen  and  one  of  oxygen  give  water- 
vapor  or  steam.  Such  volumes  or  simple  multiples  are  alone  the 
proportions  by  bulk  in  which  elements  combine.  If  any  excess  of 
either  gas  be  mixed  and  combination  attempted,  only  the  stated  pro- 
portions really  combine,  the  excess  remaining  unaltered.  Further, 
following  Gay-Lussac,  on  weighing  these  similar  and  equal  volumes 
of  hydrogen,  chlorine,  and  oxygen,  we  find  that  the  chlorine  is 
35.5  times  as  heavy  as  hydrogen,  and  oxygen  16  times  as  heavy  as 
hydrogen. 

In  1811  and  1814,  Avogadro  and  Ampere,  reasoning  on  the  fact 
that  all  gases  are  similarly  affected  by  variations  of  temperature  and 
pressure,  concluded  that  all  must  have  been  similarly  constituted — 
similarity  in  properties  always  indicating  similarity  in  character  or 
nature  ; in  other  words,  that,  if  equal  volumes  of  gases  be  taken,  each 
will  contain  the  same  number  of  molecules,  similar  in  size  and  equally 

* Only  the  atomic  weights  of  the  above  and  a few  of  the  chief 
metallic  elements  need  be  committed  to  memory  ; others  can  be 
sought  out  as  occasion  may  require.  A complete  Table  of  Atomic 
Weights  is  given  at  the  end  of  the  volume. 


CHEMICAL  PHILOSOPHY. 


45 


distant  apart.  The  deduction  is  obvious.  The  weights  of  molecules 
of  elements  (that  is,  of  pairs  of  atoms,  and  therefore  of  atoms  them- 
selves) must  differ  to  the  extent  that  the  weights  of  equal  volumes 
of  those  elements  differ.  Equal  volumes  of  hydrogen,  chlorine,  and 
oxygen,  weighing  respectively  1,  35.5,  and  16,  and  each  of  these  vol- 
umes containing  an  equal  number  of  molecules,  each  formed  of  two 
atoms,  it  follows  that  the  relative  weights  of  the  atoms  will  be  1, 
35.5,  and  16. 

It  will  thus  be  seen  that  the  weight  of  the  volume  in  which  an 
elemmnt  combines,  and. the  actual  weight  in  which  it  combines,  irre- 
spective of  volume,  are  identical.  For  instance,  we  should  find  by 
experiment  that,  as  a simple  matter  of  fact,  oxygen  unites  with  other 
elements  in  proportions  of  16  by  weight,  while  hydrogen  combines 
in  proportions  of  1.  Turning,  then,  to  experiments  on  the  volumes 
in  which  hydrogen  or  oxygen  combine,  and  having  ascertained  those 
volumes,  and  then  having  weighed  them,  we  should  find  that  the 
oxygen  volume  weighs  16,  while  the  hydrogen  weighs  1.  In  com- 
pounds in  which  hydrogen  were  found  in  proportions  of  1 grain, 
oxygen  would  be  found  in  proportions  of  16  grains.  In  gaseous 
compounds  in  which  hydrogen  were  found  in  proportions  of,  say,  27 
ounces  by  measure,  oxygen  would  be  found  in  proportions  of  27 
ounces  by  measure ; the  27  ounces  of  hydrogen  would  be  found  to 
weigh  1 grain,  and  the  27  ounces  of  oxygen  to  weigh  16  grains. 

Thus  the  two  great  facts  or  laws  respecting  chemical  compounds 
which  Dalton  laid  down  by  ascertaining  the  exact  weights  in  which 
bodies  combine,  Gay-Lussac  confirmed  by  experiments  on  the  exact 
volumes  in  which  elements  combine.  Further,  Gay-Lussac’s  experi- 
ments and  Avogadro’s  reasoning  strongly  supported  Dalton’s  theory 
of  atoms. 


Eecapitulation. 

What  are  atomic  weights  or  combining  weights  ? First,  they  are 
represented  by  the  smallest  proportion  (relative  to  1 part  of  hydro- 
gen) in  which  an  element  migrates  from  compound  to  compound. 
Thus  1 part  by  weight  of  hydrogen  can  be  eliminated  from  18  similar 
parts  of  water  by  action  of  certain  metals,  leaving  1 of  hydrogen  and 
16  of  oxygen  combined  with  the  metal.  From  the  latter  compound 
1 more  of  hydrogen  is  eliminated  by  a second  experiment  with  more 
metal,  leaving  16  of  oxygen  combined  with  the  metal.  In  these  and 
other  well-known  reactions  16  parts  of  oxygen  take  part  in  the 
various  operations ; 16,  therefore,  is  the  probable  atomic  weight  of 
oxygen;  and  so  with  other  elements  and  radicals.  Secondly,  the 
weights  of  the  atoms,  or  the  atomic  weights  of  the  gaseous  elements 
already  studied,  must  differ  from  each  other  to  the  extent  that  equal 
volumes  of  those  elements  differ  in  weight.  For  equal  volumes  of  an 
element  contain  an  equal  number  of  molecules  equal  in  size  (Avoga- 
dro’s and  Ampere’s  law),  and  each  molecule  is  composed  of  two 
atoms ; so  that  equal  volumes  of  elements  contain  an  equal  number 
of  atoms.  Now,  bulk  for  bulk,  chlorine  is  thirty-five  and  a half 
(35.5)  times  as  heavy  as  hydrogen ; so  that  the  molecule  of  chlorine 
must  be  35.5  times  the  weight  of  the  molecule  of  hydrogen ; for 


46 


GENERAL  PRINCIPLES  OF 


molecules  are  equal  in  bulk.  And  as  the  molecules  of  chlorine  and 
hydrogen  contain  two  atoms  each,  the  atom  of  chlorine  must  be  35.5 
times  as  heavy  as  that  of  hydrogen.  The  actual  weight  of  atoms 
can  never  be  ascertained,  but  that  is  of  little  consequence  if  we  can 
only  determine,  wdth  exactitude,  their  comparative  weights.  Com- 
paring, then,  all  atomic  weights,  sometimes  obscurely  termed  equiva- 
lents, with  each  other,  and  selecting  hydrogen  as  the  standard  of 
comparison  (because  it  is  the  lightest  body  known,  and  therefore, 
probably,  will  have  the  smallest  atomic  weight),  and  assigning  to  it 
the  number  1,  we  see  that  the  atomic  weight  of  chlorine  will  be 
represented  by  the  number  35.5.  By  parity  of  reasoning  the  atomic 
weight  of  oxygen  is  1 6 ; for  oxygen  is  found,  by  experiment,  to  be 
16  times  as  heavy  as  hydrogen.  Similarly  the  atomic  weight  of 
nitrogen  is  found  to  be  14.  The  atomic  weight  of  carbon  is  12 — not 
because  its  vapor  has  been  proved  to  be  12  times  as  heavy  as  hydro- 
gen, for  it  has  never  yet  been  converted  into  the  gaseous  state,  but 
because  no  gaseous  compound  of  carbon,  which  has  been  analyzed, 
has  been  found  to  contain  in  2 volumes  (one  of  which,  if  hydrogen, 
would  weigh  1 part)  less  than  12  parts  of  carbon. 

By  thus  weighing  equal  volumes  of  gaseous  elements,  or  equal 
volumes  of  gaseous  compounds  of  non-volatile  elements,  and  ascer- 
taining by  analysis  the  proportion  of  the  non-volatile  element  whose 
atomic  weight  is  being  sought,  to  the  volatile  element,  whose  atomic 
weight  is  known,  the  atomic  weights  of  a large  number  of  the  ele- 
ments have  been  determined.  Some  of  the  elements,  however,  do 
not  form  volatile  compounds  of  any  kind ; the  stated  atomic  weights 
of  these  elements,  therefore,  are  at  present  simply  the  proportions  by 
weight  in  which  they  combine  with  or  displace  elements  w^hose  atomic 
w^eighfs  have  been  determined,  the  proportion  being  in  most  cases 
checked  by  isomorphic  considerations  and  the  relation  of  the  element 
to  other  forces,  especially  heat.*  [Vide  infra.) 

Molecular  Weight  and  Molecular  Volume. 

The  weight  of  the  molecule  is  simply  the  sum  of  the  weights  of  its 
atoms  ; thus 

H2=2,  0^=32,  Cl2=71,  1120  = 18,  HC1  = 36.5. 

Molecular  Volume. — If  the  quantities  just  mentioned  be  weighed 
out  (in  grains  or  other  weights),  or  if  the  molecular  weight  of  any 
gases  or  liquids  be  taken  and  exposed  to  similar  (high)  temperatures 

* Isomorphous  bodies  (from  tVo?,  ?sos,  equal,  and  f^op<phf  morphs,  form) 
are  those  which  are  similar  in  the  shape  of  their  crystals.  The  iden- 
tity in  crystalline  form  is  so  commonly  associated  with  similarity  of 
constitution  that  non-crystalline  substances  resembling  each  other  in 
structure  are  often  regarded  as  isomorphous.  When  one  element 
unites  with  another  in  more  than  one  proportion,  and  consequently 
its  atomic  weight  is  uncertain,  the  isomorphism  of  either  of  its  com- 
pounds with  some  other  compound  of  known  constitution  is  usually 
accepted  as  decisive  evidence  as  to  which  proportion  is  atomic.  The 
specific  heat  of  elements  wid  be  treated  of  subsequently. 


CHEMICAL  PHILOSOPHY. 


47 


and  pressures,  they  loill  all  he  found  to  occupy  the  same  volume. 
Conversely,  if  equal  volumes  of  gases  or  vapors  be  measured  out, 
and  then  the  whole  weighed,  the  resulting  figures  (all  referred  to  2 
of  hydrogen  as  a starting-point  or  standard)  are  the  molecular  weights 
of  the  respective  substances.  Thus  a measure  of  hydrogen  (about 
half  a gallon)  which,  at  a temperature  of,  say,  300^  F.  or-  400^  F., 
and  common  atmospheric  pressure,  would  weigh  2 grains,  would  in 
the  case  of  vapor  of  water  (steam)  weigh  18  grains.  Hence  we  are 
justified  in  considering,  indeed  compelled  to  consider,  the  molecule 
of  water  to  contain  two  atoms  of  hydrogen  (=2)  and  one  of  oxygen 
(=16),  and  its  formula  to  be  H^O  (=18),  and  not  H^Og,  in  which 
case  its  vapor  would  be  twice  as  heavy  as  it  really  is  found  to  be. 

Construction  of  Formuloe. — The  composition  of  hydrochloric  acid 
(HCl),  water  (H2O),  ammonia  (NH3),  carbonic  acid  gas  (CO2),  or 
any  other  compound,  as  well  as  the  weight  of  an  element  that  may 
be  concerned  in  its  formation,  cannot  be  ascertained  by  actual  ex- 
periment until  the  student  is  far  advanced  in  practical  chemistry — • 
until  he  is  able  to  analyze  not  only  qualitatively , but,  by  help  of  a 
balance,  quantitatively.  The  percentage  composition  of  a substance 
having  been  detetermined  by  quantitative  analysis,  its  formula  is 
constructed  by  aid  of  the  foregoing  and  other  theoretical  considera- 
tions. The  correctness  of  such  formulae  can  be  verified  by  expert 
analysts,  but  must  be  taken  for  granted  by  learners.  This  subject 
will  again  be  referred  to  in  the  latter  part  of  this  Manual. 

Quantivalence  of  Atoms. 

Turning  from  the  weights  of  atoms,  their  value  may  now  be  con- 
sidered ; their  quantivalence  (from  quantitas,  quantity,  and  valens, 
being  worth)  may  be  stated.  The  chemical  value  of  atoms  in  relation 
to  each  other  may  be  compared  to  the  exchangeable  value  of  coins. 
As  compared  with  a penny  (IcZ.)  a groat  (45.)  is  four- valued;  as 
compared  with  hydrogen  carbon  is  quadrivalent.  Here  again  hydro- 
gen is  conventionally  adopted  as  the  standard  of  comparison.  An 
atom  of  oxygen  in  its  relations  to  an  atom  of  hydrogen  is  bivalent 
(pronounced  thus,  biv'-a-lent;  of  double  worth,  from  bis,  twice,  and 
valens) ; an  atom  of  it  will  displace  two  atoms  of  hydrogen,  or  com- 
bine with  the  same  number ; nitrogen  is  usually  trivalent  (triv'-a- 
lent ; from  tres,  three,  and  valens) ; and  carbon  quad-riv'-a-lent  (from 
quatuor,  four,  or  quater,  four  times,  and  valens).  Chlorine,  iodine, 
and  bromine,  as  well  as  potassium,  sodium,  and  silver  among  the 
metals,  are,  like  hydrogen,  univalent  (u-niv'-a-lent ; from  unus,  one, 
and  valens).  Barium,  strontium,  calcium,  magnesium,  zinc,  cad- 
mium, mercury,  and  copper,  like  oxygen,  are  bivalent.  Phosphorus, 
arsenicum,  antimony,  and  bismuth,  like  nitrogen,  usually  exhibit 
trivalent  properties  ; but  the  composition  of  certain  compounds  of 
these  elements  shows  that  the  several  atoms  are  sometimes  quinquiv- 
alent (quin-quiv'-a-lent ; quinquies,  five  times,  and  valens).  Gold 
and  boron  are  trivalent.  Silicon  (the  characteristic  element  of  Hint 
and  sand),  tin,  aluminium,  platinum,  and  lead  resemble  carbon  in 
being  quadrivalent.  Sulphur,  chromium,  manganese,  iron,  cobalt, 
and  nickel  are  sexivalent  (sex-iv'-a-lent ; from  sex,  six,  or  sexies,  six 


48 


GENERAL  PRINCIPLES  OF 


times,  and  valens),  but  frequently  exert  only  bivalent,  trivalent,  or 
quadrivalent  activity.  This  quantivalence  (quant-iv'-a-lenee  ; from 
quantitas,  quantity,  and  valens),  also  termed  atomicity  (maximum 
quantivalence),  dynamicity,  and  equivalence  of  elements,  may  be 
ascertained  at  any  time  on  referring  to  the  Table  of  the  Elements  at 
the  end  of  this  volume,  where  Roman  numerals,  i,  ii,  iii,  iv,  v,  vi,  are 
attached  to  the  symbols  of  each  element  to  indicate  atomic  univa- 
lence, bivalence,  trivalence,  quadrivalence,  quinquivalence,  or  sexiva- 
lence.  Dashes  (H',  0",  N'")  similar  to  those  used  in  accentuating 
words  are  often  used  instead  of  figures  in  expressing  quantivalence. 
The  quantivalence  of  elements,  as  they  one  after  another  come  under 
notice,  should  be  carefully  committed  to  memory;  for  the  composition 
of  compounds  can  often  be  thereby  predicated  with  accuracy  and  re- 
membered with  ease.  For  instance,  the  hydrogen  compounds  of  chlo- 
rine, Cl',  oxygen,  0",  nitrogen,  N'",  and  carbon,  C"",  will  be  respec- 
tively H'Gl',  and  one  univalent  atom,  H', 

balancing  or  saturating  one  univalent  atom  Cl' ; two  univalent  atoms, 
H'2,  and  one  bivalent  atom  0",  saturating  each  other;  three  univa- 
lent atoms,  H'g,  and  one  atom  having  trivalent  activity,  N'",  satu- 
rating each  other ; and  four  univalent  atoms,  H'^,  and  one  quadriva- 
lent atom,  C"",  saturating  each  other.  Carbonic  acid  gas, 
again,  is  a saturated  molecule  containing  one  quadrivalent  and  two 
bivalent  atoms. 

The  subject  of  quantivalence  will  he  further  explained  after  the 
first  six  metals  have  been  studied,  luhen  abundant  illustrations  of 
its  applications  will  have  occurred. 

DEFINITIONS. 

Chemistry  is  the  study  of  the  chemical  force. 

The  Chemical  Force,  like  other  forces,  cannot  be  described,  for, 
like  them,  it  is  only  known  by  its  effects.  It  is  distinguished  from 
other  forces  by  the  fact  that  it  produces  an  entire  change  of  proper- 
ties in  the  bodies  on  which  it  is  exerted.  The  chemical  force  resides 
in  the  atoms  of  elements;  it  is  exerted  only  between  definite  weights 
and  volumes  of  matter. 

An  Element  is  a substance  which  cannot  by  any  known  means  be 
resolved  into  any  simpler  form  of  matter. 

An  Atom  of  any  element  is  a particle  so  small  that  it  undergoes 
no  further  subdivision  in  chemical  transformations. 

A Molecule  is  the  smallest  particle  of  matter  that  can  exist  in  a 
free  state. 

A mere  Mixture  of  substances  is  one  in  which  each  ingredient  re- 
tains its  properties. 

A Chemical  Compound  is  one  in  which  definite  weights  of  con- 
stituents have  combined,  and  during  combination  have  undergone  an 
entire  change  of  properties.  A “ compound”  in  pharmacy  is  an  in- 
timate mixture  of  substances,  but  still  only  a mixture;  it  is  not  a 
chemical  compound,  the  ingredients  have  not  entered  into  chemical 
union  or  combination. 

Combustion  is  a variety  of  chemical  combination,  a variety  in 


CHEMICAL  PHILOSOPHY. 


49 


which  the  chemical  union  is  sufficiently  intense  to  produce  heat  and, 
generally,  light. 

The  Law  of  Diffusion  is  one  under  which  gases  mix  with  each 
other  at  a rate  which  is  in  inverse  proportion  to  the  square  root  of 
their  relative  weights ; that  is,  irrespective  of  and  even  in  spite  of 
their  comparative  lightness  or  heaviness. 

A Chemical  Symbol  is  a capital  letter,  or  a capital  and  one  small 
letter.  It  has  four  functions,  namely  : — 

1.  It  is  short-hand  for  the  name  of  the  element. 

2.  It  represents  one  atom  of  the  element. 

3.  It  stands  for  a constant  weight  of  the  element — the  atomic 

weight  or  combining  weight. 

4.  Symbols  represent  single  and  equal  volumes  of  gaseous  ele- 

ments. 

A Chemical  Formula  represents  a molecule  either  of  an  element 
or  of  a compound.  It  also  has  four  functions  : — 

1.  It  indicates  at  a glance  the  names  of  the  elements  in  a mole- 

cule. 

2.  Its  symbol,  or  symbols,  together  with  a small  figure  attached 

to  the  foot  of  any  symbol,  show  the  number  of  atoms  in  a 
molecule. 

3.  It  stands  for  a constant  weight  of  a compound — the  molecular 

w^eight,  that  is,  the  sum  of  the  weights  of  the  atoms  in  a 
molecule. 

4.  It  represents  two  volumes  of  the  substance  in  the  state  of  gas 

or  vapor.  (Ift  the  case  of  bodies  which  cannot  be  volatil- 
ized this  statement  is  only  probably  correct.) 

A Chemical  Equation  or  a Chemical  Diagram  is  a collection  of 
formulae  and  symbols  so  placed  on  paper  as  to  form  a picture  or  illus- 
tration of  the  state  of  things  before  and  after  that  attack  of  mole- 
cules on  each  other  which  results  in  the  formation  of  molecules  of 
new  substances. 

A Solid  is  a substance  the  molecules  of  which  are  more  or  less 
immobile,  though  probably  not  in  absolute  contact. 

A Liquid  is  a substance  the  molecules  of  which  so  freely  move 
about  each  other  that  it  readily  assumes  and  retains  the  form  of  any 
vessel  in  which  it  is  placed. 

A Gas  is  a substance  the  molecules  of  which  are  so  far  apart  that 
they  seem  to  have  lost  all  attraction  for  each  other,  and,  indeed,  to 
have  acquired  the  property  of  repulsion  to  such  an  extent  that  they 
are  only  prevented  from  receding  to  a still  greater  extent  by  the 
pressure  of  surrounding  matter.  Motion  is  especially  characteristic 
of  gaseous  fluids. 

The  Three  Laws  regulating  Chemical  Combination  [either  by 
weight  or  volume). 

First.  A definite  compound  always  contains  the  same  elements 
and  the  same  proportions  of  those  elements — by  weight  or  volume. 

Second.  AVhen  two  elements  unite  in  more  than  one  proportion, 
they  do  so  in  simple  multiples  of  that  proportion. 


50 


GENERAL  PRINCIPLES  OF 


Third.  The  proportions  in  which  two  elements  unite  with  a third, 
are  the  proportions  in  which  they  unite  with  each  other. 

Atomic  Weights  are,  first,  the  proportions  in  which  elements  are 
found  to  combine  with  each  other  by  weight.  (The  figures  showing 
these  proportions  are  purely  relative,  but  all  chemists  agree  to  make 
this  relation  fixed  by  giving  the  number  1 to  hydrogen.)  Secondly, 
they  are  the  weights  of  equal  volumes  of  elements  in  the  state  of  gas 
(relative  to  1 of  hydrogen). 

Molecular  Weights.— These  are  the  weights  of  equal  volumes  of 
gases  or  vapors,  under  equal  circumstances  of  temperature  and  pres- 
sure, and  relative  not  to  1 but  to  2 of  hydrogen.  In  the  case  of  non- 
volatile bodies  molecular  weight  is  deduced  from  the  observed  analo- 
gies of  bodies  with  those  whose  molecular  weight  admits  of  proof. 

Quantivalence  of  Atoms. — The  observed  power,  force,  or  value 
for  work  of  an  atom — relative  to  1 of  hydrogen. 


The  Learner  is  recommended  to  read  the  foregoing  para- 
graphs ON  THE  General  Principles  of  Chemical  Philosophy 

CAREFULLY  ONCE  OR  TWICE,  THEN  TO  STUDY  (EXPERIMENTALLY,  IF 
possible)  the  following  PAGES,  RETURNING  TO  AND  READING  OVER 

THE  General  Principles  from  time  to  time,  until  they  are 
THOROUGHLY  COMPREHENDED. 


QUESTIONS  AND  EXERCISES. 

42.  What  do  you  understand  by  chemical  action  ? Give  examples. 

43.  How  is  the  chemical  distinguished  from  all  other  forces  ? 

44.  Adduce  evidence  that  elements  exist  in  compounds  ; that  sul- 
phide of  iron,  for  instance,  still  contains  particles  of  sulphur  and 
iron,  though  it  possesses  properties  so  different  from  these  elements. 

45.  Define  the  term  atom. 

46.  AVhat  condition  is  essential  for  the  manifestation  of  chemical 
force  ? 

46.  Can  an  atom  exist  in  an  uncombined  state?  and  when  are  the 
atoms  of  an  element  most  potent  to  enter  into  chemical  combination  ? 

48.  What  is  a molecule  ? 

49.  How  may  the  results  of  chemical  reactions  be  expressed  on 
paper? 

50.  Enumerate  the  functions  of  a symbol. 

51.  Give  the  additional  functions  of  a chemical  formula. 

52.  Describe  by  a diagram  or  an  equation  the  reaction  which 
ensues  when  red-hot  charcoal  is  plunged  into  oxygen  gas. 

53.  Draw  diagrams  representing  the  formation  of  P2O5,  SO2,  and 
Pel.,  respectively. 

54.  Enumerate  the  differences  between  the  physical  state  of  the 
molecules  in  a solid,  a liquid,  and  a gas. 

55.  State  the  law  of  constant  proportions. 


CHEMICAL  PHILOSOPHY. 


51 


56.  State  the  law  of  multiple  proportions. 

57.  State  the  law  of  reciprocal  proportions. 

58.  Give  illustrations  of  the  above  laws. 

59.  Describe  the  origin  and  use  of  the  atomic  theory. 

60.  What  do  you  understand  by  the  atomic  weight,  and  the  mo- 
lecular weight  of  an  element  ? 

61.  Representing  the  weight  of  an  atom  of  hydrogen  as  1,  what 
will  be  the  atomic  weights  of  carbon,  sulphur,  nitrogen,  and  iodine  ? 
Give  reasons  for  considering  the  stated  weights  to  be  correct. 

62.  In  what  proportion,  by  volume,  do  elements  in  the  gaseous 
state  chemically  combine  ? 

63.  What  relation  exists  between  the  volumes  of  elements  in  the 
gaseous  state  and  their  atomic  weights?  Give  the  explanation  for 
this. 

64.  Is  there  any  difference  between  the  molecular  volume  of  a 
simple  or  of  a compound  gas  ? 

65.  Define  isomorphism. 

66.  Explain  the  value  of  isomorphism  as  evidence  of  atomic 
weight. 

67.  What  is  to  be  understood  by  the  quantivalence  of  an  element? 
Give  examples  of  univalent,  bivalent,  trivalent,  and  quadrivalent 
atoms. 

68.  How  may  the  quantivalence  of  an  element  be  expressed  in  its 
atomic  symbol  ? 

69.  Give  the  formulae  of  two  or  three  compounds  in  which  the 
quantivalence  of  one  atom  is  saturated  by  the  combined  quanti- 
valence of  others. 


The  reader  is  also  recommended  to  question  himself,  or  be  ques- 
tioned, on  the  “definitions”  given  on  pages  48  to  50. 


THE  ELEMENTS  AND  THEIR  COMPOUNDS. 

Having  thus  obtained  a general  idea  of  the  nature  of  such  elements 
as  have  especial  interest  for  the  medical  and  pharmaceutical  stu- 
dent, and  which  indeed  are  all  with  which  any  student  of  chemistry 
should  at  present  occupy  his  attention,  we  may  pass  on  to  consider 
in  detail  the  relations  of  the  elements  to  each  other.  The  elements 
themselves,  in  the  free  condition,  are  seldom  used  in  medicine,  being 
nearly  always  associated,  bound  together  by  the  chemical  force ; in 
this  combined  condition,  therefore,  they  must  be  studied.  Each 
combination  of  elements  or  chemical  compound  will,  in  the  following 
pages,  be  regarded  as  containing  two  parts  or  roots,  two  radicals  : 
the  one  usually  metallic,  or,  to  speak  more  generally,  basylous  ; the 
other  commonly  a non-metallic,  simple  or  complex,  acidulous  radical. 
The  basylous  radicals,  or  metals,  will  be  considered  first,  the  acidu- 
lous radicals  afterwards.  Each  radical  will  be  studied  from  two 
points  of  view,  the  synthetical  and  the  analytical : that  is  to  say,  the 
properties  of  an  element  on  which  the  preparation  of  its  compounds 


52 


POTASSIUM. 


depends  will  be  illustrated  by  descriptions  of  actual  experiments 
(usually  performed  on  a small  scale),  and  thus  the  chemistry  of  the 
Pharmacopoeia  be  systematically  learnt;  then  the  reactions  by  which 
the  element  is  detected,  though  combined  with  other  substances, 
will  be  performed,  and  so  the  student  be  instructed  in  qualitative 
analysis.  Synthetical  and  analytical  reactions  are,  in  truth,  fre- 
quently identical,  the  object  with  which  they  are  performed  giving 
them  synthetical  interest  on  the  one  hand,  or  analytical  interest  on 
the  other. 

A good  knowledge  of  chemistry  may  be  acquired  synthetically  by 
preparing  considerable  quantities  of  the  salts  of  the  different  metals, 
or  analytically  by  going  through  a course  of  pure  qualitative  ana- 
lysis. But  the  former  plan  demands  a larger  expenditure  of  time 
than  most  students  have  to  spare,  while  under  the  latter  system  they 
generally  lose  sight  of  the  synthetical  interest  which  attaches  to  ana- 
lytical reactions.  Hence  the  more  useful  system,  now  offered,  of 
studying  each  metal,  etc.,  from  both  points  of  view,  time  being  eco- 
nomized by  the  operator  preparing  only  small  specimens  of  com- 
pounds. 

Chemical  synthesis  and  analysis,  thoughtfully  and  conscientiously 
followed,  will  insensibly  carry  the  principles  of  chemistry  into  the 
mind  and  fix  them  there  indelibly. 

POTASSIUM. 

Symbol  K.  Atomic  weight  39. 

Formula  K2.  Probable  molecular  weight  78. 

Memoranda. — The  chief  sources  of  the  potassium  salts*  are  the 
chloride  found  at  Staasfurt,  in  Prussia,  in  the  form  of  the  mineral 
Carnallite  (chloride  of  potassium  50,  chloride  of  sodium  25,  and 
chloride  of  magnesia  25,  in  100  parts) ; the  nitrate,  found  in  soils, 
especially  in  warm  countries,  and  the  compounds  of  potassium  existing 
in  plants.  The  latter,  vegetable  salts  of  potassium,  are  converted 
into  carbonate  with  some  sulphate,  etc.,  when  the  w^ood  or  other 
parts  are  burned  to  ashes.  If  the  ashes  be  lixiviated  wdth  water,  and 
the  solution  evaporated  to  dryness,  the  residue,  when  fused,  consti- 
tutes crude  potashes.  The  residue,  calcined  on  the  hearth  of  a re- 
verberatory furnace  till  wdiite,  gives  the  product  termed  peai'lash 
(Potassu  Carbonas  Impura,  U.  S.  P.).  Large  quantities  of  car- 
bonate are  thus  produced  in  North  America  and  Russia.  From  the 
native  chloride  and  from  the  carbonate  purified  by  treating  the 
pearlash  with  its  owm  weight  of  distilled  w’ater,  filtering  and  evapo- 
rating the  solution  until  it  thickens,  and  stirring  constantly  “ so  as 
to  form  a granular  salt”  {Potassu  Carbonas^  IJ.  S.  P.),  nearly  all 
other  compounds  of  potassium  are  made.  Exceptions  occur  in  cream 
of  tartar  {Potassae  Tartras  Acida,  B.  P. ; Potassii  Bitartras, 
U.  S.  P.),  wdiich  is  simply  the  purified  natural  potassium  salt  of  the 
grape-vine,  and  in  nitrate  of  potassium.  Potassium  is  a constituent 

* The  term  salt  includes  any  definite  solid  chemical  substance,  but 
more  especially  those  which  assume  a crystalline  form. 


HYDRATE  OF  POTASSIUM. 


53 


of  between  forty  and  fifty  ckemical  or  Galencial  preparations  of  the 
British  Pharmacopoeia. 

Carbonate  of  potassium  is  a white  crystalline  or  granular  powder, 
insoluble  in  alcohol,  very  soluble  in  water,  rapidly  liquefying  in  the 
air  through  absorption  of  moisture,  alkaline  and  caustic  to  the  taste. 
It  loses  all  water  at  a red  heat.  Potassii  Garhonas  Pura,  U.  S.  P., 
is  obtained  by  heating  the  bicarbonate  to  redness : the  resulting 
white  anhydrous  carbonate  is  converted  into  hydrous  granular  car- 
bonate by  solution  in  water  and  evaporation  until  a dry  granular 
salt  remains. 

Preparation. — Potassium  itself  is  isolated  with  some  difficulty  by 
distilling  a mixture  of  its  carbonate  and  charcoal.  It  rapidly  oxi- 
dizes in  the  air,  and  hence  is  always  kept  below  the  surface  of  mineral 
naphtha,  a liquid  containing  no  oxygen. 

Quantivalence. — The  atom  of  potassium  is  univalent,  K'. 

Eeactions  having  (a)  Synthetical  and  [h)  Analytical  Interest. 
[a)  Synthetical  Reactions. 

These  are  actions  utilized  in  manufacturing  preparations  of  potas- 
sium. The  word  synthesis  is  from  avvdscn^  {sunthesis),  a putting 
together,  as  opposed  to  analysis,  from  ava%vu>  [analuo),  I resolve. 

Hydrate  of  Potassium.  Caustic  Potash. 

First  Synthetical  Reaction. — Boil  together,  for  a few 
minutes,  in  a test-tube,  five  or  six  grains  of  carbonate  of 
potassium  (K.^COg)  and  a like  quantity  of  slaked  lime 
(Ca2HO)  with  a small  quantity  of  water.  Set  the  mixture 
aside  in  the  test-tube  rack  till  all  solid  matter  has  subsided. 

This  liquid  is  a solution  of  caustic  potash,  or  hydrate  of  potassium 
(KHO).  Made  of  a prescribed  strength,  it  forms  the  Liquor  Po- 
tassce,  B.  P.  (5.84  per  cent.),  and  U.  S.  P.  (5.8  per  cent.). 

The  mixture  is  known  to  be  boiled  long  enough  when  a little  of 
the  clear  liquid,  poured  into  another  test-tube  and  warmed,  gives  no 
effervescence  on  the  addition  of  an  acid  (sulphuric,  hydrochloric,  or 
acetic) — a test  whose  mode  of  action  will  be  explained  hereafter. 

Best  method  of  expressing  decompositions. — This  will  be  easy  of 
comprehension  if  what  has  already  been  stated  concerning  symbols 
and  formula  on  pages  27  to  40,  has  been  carefully  and  thoughtfully 
considered.  The  best  means  of  showing  on  paper  the  action  which 
occurs  when  chemical  substances  attack  each  other  is  by  the  employ- 
ment either  of  equations  or  diagrams.  In  an  equation  the  formulae 
of  the  salts  used  are  WTitten  on  one  line,  the  sign  of  addition  (+) 
intervening ; the  sign  of  equality  (=)  follows,  and  then  the  formulae 
of  the  salts  produced  also  separated  by  a plus  sign  (-|-).  Thus 

K^COg  -f-  Ca2HO  = 2KIPO  -f  CaCOg. 

In  this  reaction  (the  operation  just  performed)  the  metals  of  the  two 
salts  change  places : from  K.^OOg  and  Ca2IIO  there  are  produced 

5* 


54 


‘ THE  METALLIC  RADICALS. 


CaCO.^  and  KUO  (two  molecules);  from  carbonate  of  potassium  and 
hydrate  of  calcium  there  result  carbonate  of  calcium  (the  insoluble 
portion)  and  hydrate  of  potassium  (in  solution). 

In  constructing  a diagram,  or  pictorial  illustration,  of  a chemical 
reaction,  first  the  formulae  of  the  salts  used  are  written  under  each 
other  on  the  left  side  of  a leaf  of  a note-book;  secondly,  on  the  right 
are  written  the  formulae  of  the  salts  produced ; thirdly,  the  paths 
which  may  be  supposed  to  be  taken  by  the  respective  elements  are 
indicated  by  the  use  of  brackets  and  lines,  as  follows : — 


2KHO 


CaC03 


It  will  be  noticed  that  the  only  important  data  required  in  making 
either  equationary  or  diagrammatic  notes  of  decompositions  are  the 
symbolic  formulae  of  the  various  compounds  employed  or  produced. 
These  formulae  are,  in  this  manual,  given  whenever  necessary.  (Chem- 
ists obtain  them  in  the  first  instance  by  the  help  of  quantitative 
analysis.) 

Note  on  Nomenclature. — Hydrates  are  bodies  indirectly  or  directly 
derived  from  water  by 'one-half  of  its  hydrogen  becoming  displaced 
by  an  equivalent  quantity  of  another  radical.  Thus,  a piece  of 
potassium  thrown  on  to  water  (HHO)  instantly  liberates  hydrogen, 
hydrate  of  potassium  (KHO)  being  formed.  The  temperature  pro- 
duced at  the  same  time  is  sufficiently  high  to  cause  ignition  of  the 
hydrogen,  which  burns  with  a purple  flame  (owing  to  the  presence 
of  a little  vapor  of  potassium),  while  the  hydrate  of  potassium  remains 
dissolved  in  the  bulk  of  the  water.  Water  might  be  termed  hydrate 
of  hydrogen. 

Explanation. — With  regard  to  the  groups  of  atoms  represented 
by  the  symbols  CO3  and  HO,  only  a few  words  need  be  said  here. 
The  former  (CO3)  is  the  grouping  (root  or  radical)  found  in  all  car- 
bonates; it  is  termed  the  carbonic  radical,  and  is  as  characteristic  of 
carbonates  as  potassium  (K)  is  of  potassium  salts.  HO  (hydroxyl) 
is  characteristic  of  all  hydrates.  CO3  is  a bivalent  root,  HO  univa- 
lent; hence  CO3  is  found  united  with  two  univalent  atoms,  as  in 
carbonate  of  potassium,  one  bivalent  atom,  as  in 

carbonate  of  calcium,  CaCOg;  and  HO  is  found  united  in  single 
proportion  with  univalent  atoms  as  in  hydrate  of  potassium,  KIIO, 
or  in  double  proportion  with  bivalent  atoms  as  in  hydrate  of  calcium, 
Oa2HO.  The  quantivalence  of  a metal  has  only  to  be  learnt,  and 
the  formulm  of  its  carbonate  and  hydrate  are  ascertained  without 
seeing  the  formula  of  either.  The  formulae  of  all  other  metallic  salts 
are  constructed  on  the  same  principle.  But,  beyond  committing  to 
memory  the  formulae  and  quantivalence  of  the  various  groupings 
characteristic  of  carbonates,  hydrates,  nitrates,  sulphates,  acetates, 
etc.  (see  the  following  Table),  special  attention  should  not  at  present 


HYDRATE  OP  POTASSIUM. 


55 


be  devoted  to  the  subject  of  the  constitution  of  salts,  but  restricted 
.to  what  may  be  called  the  metallic  or  basylous  side  of  salts.  The 
formulae  and  quantivalence  of  the  chief  acidulous  groupings  referred 
to  and  the  symbols  and  quantivalence  of  allied  elementary  bodies  are 
included  in  the  following  table : — 


Formulce  and  Quantivalence  of  Acidulous  Radicals. 


All  chlorides  contain 
“ bromides  “ 

“ iodides  “ 

“ cyanides  “ 

“ hydrates  “ 

“ nitrates  “ 

“ chlorates  “ 

“ acetates  “ 

“ oxides  “ 

“ sulphides  “ 

“ sulphites  “ 

“ sulphates  “ 

“ carbonates  “ 

“ oxalates  “ 

“ tartrates  “ 

“ citrates  “ 

“ phosphates  “ 

“ borates  “ 


. Cl  I 

. Br 

. I 

. NO 

. HO 

• NO, 

. CIO, 

. 0,H,0,. 

• 0 ) 

. s 

■ so, 

• so,  1- 

• CO, 

. c,o. 

• C,H,0,  J 

• C,H,0,  ) 

• BO,  ] 

p a 
o gs 

p I — I 


O ^ 


• r+- 


•-j  H 


Radicals. — The  above  elements  and  compounds  are  termed  radi- 
cals, each  being  the  common  root  [radix)  in  a series  of  salts.  Why 
compound  radicals  (as  NO^,  SO4,  PO4,  etc.)  differ  in  quantivalence 
cannot  well  be  explained.  Their  constituent  atoms  doubtless  always 
exert  the  same  amount  of  attractive  force,  nearly  but  not  quite  all 
this  force  being  exerted  in  retaining  the  atoms  in  one  group,  and  the 
remainder  probably  determining  the  quantivalence.  Some  of  the 
compound  radicals  are  obtainable  in  the  free  state,  others  have  yet 
to  be  proved  capable  of  isolated  existence.* 

Pure  Solution  of  Potash. — Solution  of  potash  generally  contains  a 
trace  of  alumina  dissolved  from  the  lime  by  the  hot  alkali,  but  not 
enough  to  interfere  with  the  use  of  the  liquid  in  medicine.  If  the 
solution  is  required  for  analytical  purposes,  it  may  be  obtained  free 
from  alumina  by  avoiding  the  employment  of  heat,  in  the  manner 
suggested  by  Kedwood.  Half  a gallon  is  made  by  mixing  half  a 
pound  of  slaked  lime  with  about  three  pints  of  water,  placing  the 
mixture  in  a half-gallon  bottle  (Winchester  quart),  and  adding  to  it, 
in  small  quantities  at  a time,  a solution  of  half  a pound  of  carbonate 
of  potassium  dissolved  in  the  other  pint  of  water,  shaking  the  mixture 
well  for  several  minutes  after  each  addition.  The  whole  is  now  set 
on  one  side  till  clear;  and  then,  if  a small  quantity  poured  into  a 


* A few  modern  authors  term  these  roots  radichs,  a form  of  the 
word  more  usefully  expressive  of  little  roots  or  rootlets. 


56 


THE  METALLIC  RADICALS. 


test-tube  and  warmed  does  not  effervesce  on  the  addition  of  hydro- 
chloric acid,  the  solution  is  fit  for  use.  If  effervescence  (carbonic 
acid  gas)  occurs,  the  mixture  must  be  again  well  shaken.  If  the 
lime  be  good  and  recently  slaked,  and  the  bottle  violently  shaken 
once  every  half-hour,  the  decomposition  will  be  complete  in  about 
ten  or  twelve  hours. 

Liquor  Potassce  is  officially  directed  to  be  made  as  follows : — 

Dissolve  1 pound  of  carbonate  of  potassium  in  one  gallon  of  water; 
heat  the  solution  to  the  boiling-point  in  a clean  iron  vessel,  gradually 
mix  with  it  12  ounces  of  slaked  lime,  and  continue  the  ebullition  for 
ten  minutes  with  constant  stirring.  Then  remove  the  vessel  from  the 
fire ; and  when  by  the  subsidence  of  the  insoluble  matter  the  super- 
natant liquor  has  become  perfectly  clear,  transfer  it  by  means  of  a 
siphon  or  by  decantation  to  a green-glass  bottle  furnished  with  an 
air-tight  stopper,  and  add  distilled  water,  if  necessary,  to  make  it 
correspond  with  the  tests  of  specific  gravity  and  neutralizing-power. 
The  method  of  applying  these  tests  will  be  explained  in  subsequent 
sections. 

Solid  Potash. — Solution  of  potash  evaporated  to  dryness  in  a silver 
or  clean  iron  vessel  and  the  residue  fused  and  poured  into  moulds 
constitutes  Potassa  Caustica,  B.  P.;  Potassa,  U.  S.  P.  It  often 
contains  chloride  and  sulphates,  detected  by  nitrate  of  silver  and  a 
barium  salt,  as  described  subsequently  in  connection  with  hydro- 
chloric and  sulphuric  acids.  Potassa  cum  Calce,  U.  S.  P.,  is  a 
grayish-white  powder,  made  by  rubbing  together  equal  weights  of 
solid  potash  and  quicklime. 

Sulphurated  Potash. 

Second  Synthetical  Reaction. — Into  a test-tube  put  a few 
grains  of  carbonate  of  potassium  previously  mixed  with 
half  its  weight  of  sulphur.  Heat  the  mixture  gradually 
until  it  ceases  to  effervesce.  The  resulting  fused  mass 
poured  on  a slab  and  quickly  bottled  is  the  Potassa  Sul- 
phurata.^  Sulphurated  Potash,  of  B.  P.,or  the  Potassii  Sul- 
phuretum^  U.  S.  P. 

3K,CO,  + 4S.,  = K.,SA  + 2Iv,S3  -f  SCO, 

Carbonate  of  Sulphur.  Hyposulphite  Sulphite  of  Carbonic 

potassium.  of  potassium.  potassium.  acid  gas. 

As  met  with  in  pharmacy  this  salt  is  not  a single  definite  chemical 
compound,  but  a mixture  of  several,  in  short,  its  chemical  charac- 
ter is  well  indicated  by  its  vague  name.  When  fresh,  and  if  care- 
fully prepared  with  the  official  proportions  of  dry  ingredients,  it 
is  of  the  color  of  liver  (whence  the  old  name  “liver  of  sulphur”), 
and  consists,  as  shown  by  Watts,  of  the  salts  mentioned  in  the  fore- 
going equation,  together  with  a little  undecomposed  carbonate  of 
potassium,  with  perhaps  higher  sulphides  of  potassium  (K,S^  and 
K.^Sj) ; but  rapidly  absorbing  oxygen  from  the  air  it  soon  becomes 
green  and  yellow,  sulphite  (K.^SOg)  and  sulphate  of  potassium 
(K.,SOJ  formed,  and  ultimately  a useless  mass  of  a dirty-white 


ACETATE  OF  POTASSIUM. 


57 


color  results,  consisting  of  sulphate  and  hyposulphite,  with  generally 
some  carbonate  of  potassium  and  free  sulphur.  Moreover,  if  over- 
heated in  manufacture  the  hyposulphite  4(K2S203)  is  decomposed 
into  sulphate  3(K2S04)  and  sulphide  of  potassium.  Recently 

made,  “ about  three-fourths  of  its  weight  are  dissolved  by  rectified 
spirit.^'  It  is  occasionally  employed  in  the  form  of  ointment. 

In  preparing  large  quantities  of  sulphurated  potash,  the  test-tube 
is  replaced  by  an  earthenware  vessel  termed  a crucible  (from  crux, 
a cross,  for  originally  a cross  was  impressed  upon  the  melting-pot  as 
used  by  alchemists  and  goldsmiths ; others  derive  the  word  from  crux 
an  instrument  of  torture,  the  sense  here  being  symbolical). 

Heating  Crucibles. — Crucibles  of  a few  ounces’  capacity  may  be 
heated  in  an  ordinary  grate-fire.  Larger  ones  require  a stove  with  a 
good  draught — that  is,  2i  furnace.  Even  the  smaller  ones  are  more 
conveniently  and  quickly  heated  in  a furnace.  Half-ounce  or  one 
ounce  experimental  porcelain  crucibles  may  be  heated  in  a spirit-  or 
gas-flame ; the  air  gas-fiame  already  described  being  generally  the 
most  suitable. 


Acetate  of  Potassium. 

Third  Synthetical  Reaction. — Place  ten  or  twenty  grains 
or  more  of  carbonate  of  potassium  in  a small  disli,  and 
saturate  (satur^  full)  with  acetic  acid  ; that  is,  add  acetic 
acid  so  long  as  effervescence  is  thereby  produced ; the  re- 
sulting liquid  is  a strong  solution  of  acetate  of  potassium. 

Evaporate  most  of  the  water,  stirring  with  a glass  rod* 
to  promote  the  evolution  of  vapor;  a white  salt  remains 
which  fuses  on  the  further  application  of  heat : this  is  the 
official  Acetate  of  Potassium  (Fotassae  Acetas^  B.  P.,  and 
Potassii  Acetas^  U.  S.  P.).  If  fused  in  the  open  vessel  the 
acetate  is  liable  to  become  slightly  charred  and  discolored  ; 
this  is  prevented  by  transferring  the  solid  residue  to  a test- 
tube  or  florence  flask  before  finally  fusing.  It  forms  a wdiite 
deliquescent  foliaceous  satiny  mass,  neutral  to  test-paper, 
and  wholly  soluble  in  spirit.  A ten  per  cent,  solution  in 
water  forms  the  ‘‘Solution  of  Acetate  of  Potash, B.  P. 

K,CO,  + 2HC2H3O2  = 2KC2H3O2  + H2O  + CO2 

Carbonate  of  Acetic  Acetate  of  Water.  Carbonic 

potassium.  acid.  potassium.  acid  gas. 

Explanation  of  Formulce. — The  formula  for  one  molecule  of  ace- 
tic acid  (the  acetate  of  hydrogen)  is  HC2H3O2,  and  one  of  acetate  of 
potassium  KC2H3O2.  The  grouping,  C2H8O2,  is  characteristic  of  all 

* Glass  rod  is  usually  purchased  in  the  form  of  long  sticks.  The 
pieces  may  be  cut  to  convenient  lengths  of  from  6 to  12  inches  {vide 
p.  16),  sharp  ends  being  rounded  off  by  holding  in  a flame  for  a few 
minutes. 


58 


THE  METALLIC  RADICALS. 


acetates ; it  is  univalent,  and  may  be  shortly,  though  less  instruc- 
tively, written  A. 

Explanation  of  Process. — When  two  molecules  of  acetic  acid 
(2110^11302)  and  one  of  carbonate  of  potassium  (K2CO3)  react,  two 
molecules  of  acetate  of  potassium  (2KO2H3O2)  and  one  of  carbonic 
acid  (H2CO3)  are  produced,  the  latter  at  once  splitting  up  into  water 
(H2O)  and  carbonic  acid  gas  (CO2),  as  already  shown  in  the  equa- 
tion. 

Diagram  of  the  Reaction. — The  nature  of  the  above  operation  is 
indicated  by  an  equation ; it  (and  all  succeeding  reactions)  should 
be  expressed  in  the  student’s  note-book  as  a diagram,  similar  to  that 
just  given  in  connection  with  the  first  synthetical  reaction.  In  con- 
structing a diagram,  a little  reflection  concerning  the  formulae  of  the 
bodies  produced  will  show  how  the  symbols  in  the  formulae  of  the 
bodies  employed  are  to  be  arranged  on  the  right-hand  side  of  the 
brackets. 

Evaporation  of  water  from  a liquid  is  best  conducted  in  wide 
shallow  vessels  rather  than  in  narrow  deep  ones,  as  the  steam  can 
thus  quickly  diffuse  into  the  air  and  be  rapidly  conveyed  away  ; 
hence  a small  round-bottomed  basin  is  far  more  suitable  than  a test- 
tube  for  such  operations.  On  the  manufacturing  scale,  iron,  or  iron 
lined  with  enamel,  or  semiporcelain,  copper,  tinned  copper,  or  solid 
tin  pans  are  used.  Up  to  12  or  18  inches  diameter,  pans,  basins,  or 
dishes,  made  of  Wedgwood  w^are  or  porcelain  composition,  may  be 
employed. 

Note. — The  above  reaction  has  a general  as  well  as  a special  syn- 
thetical interest.  It  represents  one  of  the  commonest  methods  of 
forming  salts,  namely,  the  saturation  of  an  acid  with  a carbonate. 
Carbonates  added  to  acetic  acid  yield  acetates,  to  nitric  acid,  ni- 
trates, to  sulphuric  acid,  sulphates.  Many  illustrations  of  this  gene- 
ral process  occur  in  pharmacy. 

Bicarbonate  of  Potassium. 

Fourth  Synthetical  Reaction, — Make  a strong  solution  of 
carbonate  of  potassium  by  heating  in  a test-tube  a mixture 
of  several  grains  of  the  salt  with  rather  less  than  an  equal 
weight  of  water.  Through  the  cooled  solution  pass  car- 
bonic acid  gas,  slowl}'  but  continuously ; after  a time  a 
w^hite  crystalline  precipitate  of  Acid  Carbonate  or  Bicar- 
bonate of  Potassium  (KHCO3),  Potassii  Bicay'honas.^  U.  S. 
P.,  the  Bicarbonate  of  Potash  of  the  British  Pharmacopoeia 
{Potassii  Bicarbonas^  B.  P.),  will  be  formed. 

K2CO3  + H2O  -f  CO2  = 2KHCO3 

Carbonate  of  Water.  Carbonic  Bicarbonate 

potassium.  acid  gas.  of  potassium. 

The  carbonic  acid  gas  necessary  for  this  operation  is  to  be  pre- 
pared from  marble,  though  it  might  be  obtained  from  any  carbonate. 
Thus  the  previous  synthetical  reaction  could  be  made  available  for 


BICARBONATE  OF  POTASSIUM. 


59 


this  purpose,  the  carbonic  gas  evolved  on  the  addition  of  the  acetic 
acid  to  the  carbonate  of  potassium  being  conducted  into  a strong 
solution  of  more  carbonate  of  potassium  by  a^lass  tube  bent  and 
fitted  as  described  when  treating  of  oxygen  ^s.  But  motives  of 
economy  induce  the  use  of  carbonate  of  calcium,  the  form  known  as 
marble  being  always  employed.  Economy  and  convenience  also 
cause  hydrochloric  acid  to  be  used  in  preference  to  acetic  or  any 
other. 

Generate  the  carbonic  acid  gas  by  adding  common  hydro- 
chloric acid,  diluted  with  twice  its  bulk  of  water,  to  a few 
fragments  of  marble  contained  in  a test-tube  or  small  flask, 
and  conduct  the  gas  into  the  solution  of  carbonate  of 
potassium  by  a glass  tube  bent  to  a convenient  angle  or 
angles,  and  fitted  to  the  test-tube  by  a cork  in  the  usual 
way.  The  tube  may  be  replenished  with  marble  or  acid  or 
both  when  the  evolution  of  gas  is  becoming  slow.  In  work- 
ing on  any  larger  quantity  than  a few  grains  of  the  carbon- 
ate a wide  delivery  tube  should- be  employed,  or  the  end  of 
the  narrow  tube  occasionally  cleared  from  any  bicarbonate 
that  may  have  been  deposited  in  it.  The  more  economical 
official  arrangements  of  the  apparatus  employed  in  this 
process  will  be  descxfibed  under  the  corresponding  sodium 
salt. 

Deposition  of  the  Bicarbonate  explained. — Bicarbonate  of  potas- 
sium is  to  a certain  extent  soluble  in  water ; but  as  it  is  less  so  than 
the  carbonate  of  potassium,  and  as  a saturated  solution  of  the  latter 
has  been  used,  the  precipitation  of  a part  of  the  bicarbonate  inevi- 
tably occurs.  In  other  words,  the  quantity  of  water  present  is  suffi- 
cient to  keep  the  carbonate,  but  insufficient  to  retain  the  equivalent 
quantity  of  bicarbonate  in  solution. 

Properties. — Prepared  on  the  large  scale,  bicarbonate  of  potassium 
occurs  in  colorless,  n on-deliquescent,  right  rhombic  prisms ; it  has  a 
saline,  feebly  alkaline,  non-corrosive  taste. 

Effervescing  Solution  of  Potash. — A solution  of  30  grains  of  bi- 
carbonate of  potassium  in  one  pint  of  water,  charged  with  7 times 
its  bulk  (often  less)  of  carbonic  acid  gas  by  pressure,  constitutes  the 
ordinary  “ potash-water,”  the  so-called  Liquor  Potassce  Effervescens, 
B.  P. 

Notes  on  Nomenclature. — The  prefix  hi-  in  the  name  bicarbo- 
nate of  potassium,”  serves  to  recall  the  fact  that  to  a given  amount 
of  potassium  thi^  salt  contains  twice  as  much  carbonic  radical  as 
the  carbonate.  The  salt  is  really  a “ carbonate  of  potassium  and 
hydrogen”  (KHCOg) ; it  is  intermediate  between  carbonate  of  potas- 
sium (K2C0.{)  and  carbonate  of  hydrogen,  or  true  carbonic  acid 
(H.^COg) ; it  is  “ acid  carbonate  of  potassium”  or  “ hydric  potassium 
carbonate ;”  chemically,  though  not  physically,  it  is  an  acid  salt. 

Salts  whose  specific  names  end  in  the  syllable  a^e”  (carbona?^e, 
sulphate,  etc.)  are  in  general  conventionally  so  termed  when  they 


60 


THE  METALLIC  RADICALS. 


contain  an  acidulous  radical,  or  the  characteristic  elements  of  an 
acid,  whose  name  ends  in  “ «c,”  and  from  ’which  acid  they  have  been 
or  may  be  formed,  ^'hus  the  syllable  “ ate"'  in  the  words  sulpha/^e, 
nitrate,  acetate,  carl^na^e,  etc.,  indicates  that  the  respective  salts 
contain  a radical  whose  name  ended  in  ic,  the  previous  syllables, 
sulph-,  nitr-,  acet-,  carbon-,  indicating  what  that  radical  was — the  sul- 
phuric, nitric,  acetic,  or  carbonic.  Occasionally  a letter  or  syllable 
is  dropped  from  or  added  to  a word  to  render  the  name  more  eupho- 
nious ; thus  the  sulphurif;  radical  forms  sulphates,  not  sulphurates. 

Citrate  of  Potassium. 

Fifth  Synthetical  Reaction, — Dissolve  a few  grains  or 
more  of  citric  acid  (HgCgH.O^)  in  water,  and  add  carbon- 
ate (bicarbonate,  U.  S.  P.)  of  potassium  until  it  no  longer 
causes  effervescence,  and  the  solution  after  well  stirring  is 
neutral  or  faintly  acid  to  test  paper.  The  resulting  liquid 
is  a solution  of  citrate  of  potassium  (KgOgH^O^)  Liquor 
Fotassii  Citratis,^  D.  S.  P.).  Evaporated  to  dryness,  in  an 
open  dish,  a pulverulent  or  granular  residue  is  obtained, 
which  is  the  oflficial  Potassii  Citras^  U.  S.  P.,  a white  deli- 
quescent powder. 

3K.,COg  -f  -f  3H,0  -f  3CO, 

Carbonate  of  Citric  acid.  Citrate  of  Water.  Carbonic 

potassium.  potassium.  acid  gas. 

Citrates. — The  citric  radical  or  group  of  elements,  w^hich  wdth 
three  atoms  of  hydrogen  forms  a molecule  of  citric  acid,  and  with 
three  of  potassium  citrate  of  potassium,  is  a trivalent  grouping; 
hence  the  three  atoms  of  potassium  in  a molecule  of  the  citrate.  The 
full  chemistry  of  citric  acid  and  other  citrates  will  be  subsequently 
described. 

Nitrate  of  'potassium  (KNO3)  [Potassii  Nitras,  U.  S.  P.)  and 
Sulphate  of  potassium  (K2SO4)  [Potasii  Sulphas,  U.  S.  P.)  could 
obviously  also  be  made  by  saturating  nitric  acid  (HNO3), 
phuric  acid  (H2SO^),  respectively,  by  carbonate  of  potassium. 
Practically  they  are  not  made  in  that  w^ay — the  nitrate  occurring, 
as  already  stated,  in  nature,  and  the  sulphate  as  a by-product  in 
many  operations.  Both  salts  will  be  hereafter  alluded  to  in  connec- 
tion with  nitric  acid. 


Tartrate  of  Potassium. 

Sixth  Synthetical  Reaction, — Place  a few  grains  of  car- 
bonate of  potassium  in  a test-tube  with  a little  water,  heat 
to  the  boiling-point,  and  then  add  acid  tartrate  of  potas- 
sium (KIIC\II^Og  or  KHT)  till  there  is  no  more  efferves- 
cence, and  the  solution  is  neutral  to  test-paper;  a solution 
of  neutral  tartrate  of  potassium  (K2’T')  results,  the  Potassii 


POTASSIUM. 


Gl 


Tartras  of  the  United  States  Pharmacopoeia.  Crystals  (4- 
or  6-sided  prisms)  may  be  obtained  on  concentrating  the 
solution  b}^  evaporation  and  setting  the  hot  liquid  aside. 
Larger  quantities  are  made  in  the  same  way,  20  of  acid 
tartrate  and  9 of  carbonate  (with  50  of  water)  being  about 
the  proportions  necessary  for  neutrality. 

2KHC,H,0,  + K,C03  = 2K,C,H,03  + H,0  + CO, 

Acid  tartrate  of  Carbonate  of  Neutral  tartrate  Water.  Carbonic 

potassium.  potassium.  of  potassium.  acid  gas. 

Tartrates. — C^H^Og  are  the  elements  characteristic  of  all  tar- 
trates ; they  form  a bivalent  grouping ; hence  the  formula  of  the 
hydrogen  tartrate,  or  tartaric  acid,  is  H2C4H40g ; that  of  the  potas- 
sium tartrate  K204H40g;  of  the  intermediate  salt,  the  acid  potas- 
sium tartrate  (cream  of  tartar),  KHC^H^Og.  If  the  acid  tartrate  of 
one  metal  and  the  carbonate  of  another  react,  a neutral  dimetallic 
tartrate  results,  as  seen  in  Rochelle  salt  (KNaO^H^Og),  the  Soda 
Tartrate  of  the  British  Pharmacopoeia.  [Potassii  et  Sodii  Tartras, 
U.  S.  P.) 

Acid  salts  [e.  g.  KHO^H^Og),  that  is,  salts  intermediate  in  compo- 
sition between  a normal  or  neutral  salt  (e.  g.  K204H^Og)  and  an  acid 
(e.  g.  H2C4H40g)  will  frequently  be  met  with.  All  acidulous  radi- 
cals, except  those  which  are  univalent,  may  be  concerned  in  the  for- 
mation of  acid  salts. 


Iodide  of  Potassium. 

Seventh  Synthetical  Reaction. — To  a solution  of  potash, 
heated  in  a test-tube,  flask,  or  evaporating-basin,  accord- 
ing to  quantity,  add  a small  quantity  of  solid  iodine.  The 
deep  color  of  the  iodine  disappears  entirely.  This  is  due 
to  the  formation  of  the  colorless  salts,  iodide  of  potassium 
(KI)  and  iodate  of  potassium  (KIO^),  which  remain  dis- 
solved in  the  liquid.  Continue  the  addition  of  iodine  so 
long  as  its  color,  after  a few  minutes^  warming  and  stirring, 
disappears.  When  the  whole  of  the  potash  in  the  solution 
of  potash  has  been  converted  into  the  salts  mentioned, 
the  slight  excess  of  iodine  remaining  in  the  liquid  will 
color  it,  and  thus  show  that  this  stage  of  the  operation  is 
completed. 

6KHO  + 31,  = 5KI  + KIO,  -p  3H2O 

Hydrate  of  Iodine.  Iodide  of  Iodate  of  Water. 

potassium.  potassium.  potassium. 

Separation  of  the  Iodide  from  the  Iodate. — Evaporate 
the  above  solution  to  dryness.  If  both  salts  were  required, 
the  solid  mixture  might  be  digested  in  spirits  of  wine,  which 
dissolves  the  iodide,  but  not  the  iodate.  But  the  iodide 
only  is  used  in  medicine.  Mix  the  residue,  therefore  (re- 
6 


62 


THE  METALLIC  RADICALS. 


serving  a grain  or  two  for  a subsequent  experiment),  with 
about  a twelfth  of  its  weight  of  charcoal,  and  gently  heat 
in  a test-tube  or  crucible  until  slight  deflagration  ensues.* 

2KIO3  + SC,  = 2KI  4-  6CO 

Iodide  of  Carbon.  Iodide  of  Carbonic 

potassium.  potassium.  oxide. 

Under  these  circumstances  the  iodide  remains  unaffected, 
but  the  iodate  loses  all  its  oxygen,  and  is  thus  also  reduced 
to  the  state  of  iodide.  Treat  the  mass  with  a little  water, 
and  filter  to  separate  excess  of  charcoal ; a solution  of  pure 
iodide  of  potassium  results.  It  may  be  used  as  a reagent 
or  evaporated  to  a small  bulk,  and  set  aside  to  crystallize. 

This  is  the  process  mentioned  in  the  British  and  United  States 
Pharmacopoeias  [Potassii  lodidum).  “ Solution  of  Iodate  of  Potas- 
sium/’ is  also  official  as  a test-liquid. 

Properties.  — Iodide  of  Potassium  crystallizes  in  small  cubical 
crystals,  very  soluble  in  water,  less  so  in  spirit.  One  part  in  ten  of 
water  forms  “ Solution  of  Iodide  of  Potassium,”  B.  P. 

The  addition  of  charcoal  in  the  above  process  is  simply  to  facili- 
tate the  removal  of  the  oxygen  of  the  iodate  of  potassium.  Iodate 
of  potassium  (KIO3)  is  analogous  in  constitution,  and  in  composition, 
so  far  as  the  atoms  of  oxygen  are  concerned,  to  chlorate  of  potassium 
(KCIO3),  which  has  already  been  stated  to  be  more  useful  than  any 
other  salt  for  the  actual  preparation  of  oxygen  gas  itself.  Hence  the 
removal  of  the  oxygen  of  the  iodate  might  be  accomplished  by  heat- 
ing the  residue  without  charcoal.  In  that  case  the  liberated  oxygen 
would  be  detected  on  inserting  the  incandescent  extremity  of  a strip 
of  wood  into  the  mouth  of  the  test-tube  in  which  the  mixture  of 
iodide  and  iodate  had  been  heated.  The  charcoal,  however,  burns 
out  the  oxygen  more  quickly,  and  thus  economizes  heat  and  time. 

Note. — The  formula  of  iodide  of  potassium  (KI)  shows  that  the 
salt  contains  potassium  and  iodine  in  atomic  proportions.  A refer- 
ence to  the  table  of  atomic  weights  at  the  end  of  the  volume,  and  a 
rule-of-three  sum,  would  therefore  show  what  weight  of  salt  is  pro- 
ducible from  any  given  weight  of  iodine. 

Detection  of  Iodate  in  Iodide  of  Potassium, — Iodate  of 
potassium  remaining  as  an  impurity  in  iodide  of  potassium 

* Deflagration  means  violent  burning,  from  Jlagratus^  burnt  (JlagrOy 
I burn),  and  de.  a prefix  augmenting  the  sense  of  the  word  to  which 
it  may  be  attached.  Paper  thrown  into  a fire  simply  burns,  nitre 
deflagrates.  Z>^-tonate  (detono)  is  a precisely  similar  word,  meaning 
to  explode  with  violent  noise. 

If,  in  tlie  operation  of  lieating  iodate  of  potassium  with  charcoal, 
excess  of  the  latter  be  employed,  slight  incandescence  rather  than 
dtdlagration  occurs  ; if  the  charcoal  be  largely  in  excess,  the  reduc- 
tion of  the  iodate  to  iodide  of  potassium  is  effected  without  visible 
deflagration  or  even  incandescence. 


POTASSIUM. 


63 


may  be  detected  by  adding  to  a solution  of  the  latter  salt 
some  tartaric  acid,  shaking,  and  then  adding  mucilage  of 
starch  ; blue  “ iodide  of  starch’’  is  formed  if  a trace  of 
iodate  be  present,  but  not  otherwise.  The  tartaric  acid 
liberates  iodic  acid  (HIO3)  from  the  iodate  of  potassium 
and  hydriodic  acid  (HI)  from  the  iodide  of  potassium; 
neither  acid  alone  attacks  starch,  but  by  reaction  on  each 
other  the  two  give  rise  to  free  iodine  which  then  forms  the 
blue  color.  This  experiment  should  be  tried  on  a sample  of 
pure  iodide  of  potassium  and  on  a grain  or  two  of  the  im- 
pure iodide  reserved  from  the  previous  experiment. 

HIO3  + 5HI  ==  3H,0  -f  SJ,. 

Note  on  Nomenclature. — The  syllable  ide  attached  to  the  syllable 
iod,  in  the  name  “ iodide  of  potassium,”  indicates  that  the  element 
iodine  is  combined  with  the  potassium.  An  locate,  as  already  ex- 
plained, is  a salt  containing  the  characteristic  elements  of  iod^c  acid 
and  all  iodic  compounds.  Salts  one  of  whose  names  ends  in  ide  are 
those  which  are,  or  may  be,  formed  from  elements.  The  names  of 
salts  which  are,  or  may  be,  formed  from  compounds  include  other 
syllables,  ate  being  one  (see  page  59).  The  only  other  syllable  is 
ite,  which  is  included  in  the  names  of  salts  which  are,  or  may  be, 
formed  from  acids  and  radicals  whose  names  end  in  ous : thus  hypo- 
sulph^Ye  of  sodium,  etc.  To  recapituate : A salt,  whose  name  ends 
in  ate  contains  a compound  acidulous  radical  whose  name  ends  in 
ic  ; a salt  whose  name  ends  in  ite  contains  a compound  acidulous 
radical  whose  name  ends  in  ous  ; a salt  whose  name  ends  in  ide  con- 
tains an  element  for  its  acidulous  radical.  Thus  sulph^(ic  relates  to 
sulphur,  sulph^^e  to  the  sulphurous  radical,  sulpha^^e  to  the  sulphuric 
radical,  and  so  on  with  other  “ ides,”  “ ites,”  or  ‘‘  ates.” 

Bromide  of  Potassium  [Potassii  Bromidum,  B.  P.). — This  salt 
is  identical  in  constitution  with  iodide  of  potassium,  and  may  be  made 
in  exactly  the  same  way,  bromine  being  substituted  for  iodine.  The 
formula  of  bromic  acid  is  HBrOg.  It  will  be  noticed  that  the  follow- 
ing equations  are  similar  in  character  to  those  showing  the  prepara- 
tion of  iodide  of  potassium. 

6KHO  + SBrg  = 5KBr  + KBrOg  + 3H,0 

Hydrate  of  Bromine.  Bromide  of  Bromate  of  Water, 

potassium.  potassium.  potassium. 

2KBr03  + 3C\  = 2KBr  + 6CO 

Bromate  of  Carbon.  Bromide  of  Carbonic 

potassium.  potassium.  oxide. 

Potassii  Bromidum,  U.  S.  P.,  is  made  by  decomposing  solution 
of  bromide  of  iron  (Fel2)  by  solution  of  pure  carbonate  of  potassium 
(K2OO3),  evaporating,  and  crystallizing. 

Manganates  of  Potassium. 

Eighth  Snythetical  Reaction, — Place  a fragment  of  solid 
caustic  potash  (KHO),  with  about  the  same  quantity  of 


64 


THE  METALLIC  RADICALS. 


chlorate  of  potassium  (KCIO3),  and  of  black  oxide  of  man- 
ganese (MnO.^),  on  a piece  of  platinum  foil.*  Hold  the  foil 
by  a small  pair  of  forceps  or  tongs  in  the  flame  of  a blow- 
pipe for  a few  minutes  until  the  fused  mixture  has  become 
dark  green#  This  color  is  that  of  manganate  of  potassium 
(K^MnOJ. 

GKHO  + KCIO3  + 3MnO,  = SK^MiiO,  + KCl  + 3H,0 

Hydrate  of  Chlorate  of  Black  oxide  of  Manganate  of  Chloride  of  Water, 
potassium.  potassium.  manganese.  potassium.  potassium. 

Ninth  Synthetical  Reaction, — Permanganate  of  Potas- 
sium (K2Mn^Og)  {Potassii  Permanganas^  U.  S.  P.),  which 
is  purple,  is  obtained,  or  rather  a solution  of  it,  on  placing 
the  foil  and  its  adherent  mass  in  water,  and  boiling  for  a 
short  time. 

SK^MnO,  + 2H2O  = K^Mn^Og  + 4KHO  + MnO., 

Manganate  of  Water.  Permanganate  Hydrate  of  Black  oxide 

potassium.  of  potassium.  potassium,  of  manganese. 

On  the  large  scale,  the  potash  set  free  in  the  reaction  is  neutral- 
ized by  sulphuric  or  carbonic  acid,  and  the  solution  evaporated  to 
the  crystallizing  point.  Further  details  will  be  given  in  connection 
with  manganese. 

Solutions  of  manganate  or  permanganate  of  potassium  and  of 
sodium  so  readily  yield  their  oxygen  to  organic  matter,  that  they  are 
used  on  the  large  scale  as  disinfectants,  under  the  name  of  “ Condy’s 
Disinfecting  Fluids.” 

Synthetical  Reactions  bringing  under  consideration  the  remain- 
ing official  compounds  (namely,  bichromate,  arsenite,  chlorate,  cyan- 
ide, ferrocyanide,  and  ferridcyanide  of  j)otassium)  are  deferred  at 
present. 


(&)  Reactions  having  Analytical  Interest  [Tests). 

Note. — These  are  reactions  utilized  in  searching  for  small  quanti- 
ties of  a substance  (in  the  present  instance  of  potassium)  in  a solution. 
They  are  best  performed  in  test-tubes  or  other  small  vessels.  Each 
should  be  expressed,  in  the  form  of  an  equation  or  diagram,  in  the 
student’s  note-book.  All  previous  or  future  equations  given  in  this 
volume  should  he  transferred  to  the  note-hook  in  the  form  of  dia- 
grams similar  to  that  given  on  page  54. 

First  Analytical  Reaction. — To  a solution  of  any  salt  of 

* The  foil  may  be  1 inch  broad  by  2 long.  No  ordinary  flame  will 
melt,  or  common  chemical  substance  attack  platinum  ; hence  the 
same  piece  may  be  used  in  experiments  over  and  over  again.  Metals 
form  a fusible  alloy  with  plaiinum,  and  phosphorus  rapidly  attacks 
it,  hence  such  substances,  as  well  as  mixtures  likely  to  yield  them, 
should  be  heated  in  a small  porcelain  crucible. 


POTASSIUM. 


65 


potassium  (chloride,*  for  example)  add  solution  of  per- 
chloride  of  platinum  (PtClJ,  and  stir  the  mixture  with  a 
glass  rod ; yellow  double  chloride  of  platinum  and  potas- 
sium (PtC1^2KCl)  will  be  precipitated.f 

Explanation. — The  precipitate  is,  practically,  insol i!6le  in  water. 
It  is  for  this  reason  that  a very  small  quantity  of  any  soluble  potas- 
sium salt  (or,  rather,  of  the  potassium  in  that  salt)  is  thrown  out  of 
solution  by  perchloride  of  platinum. 

Precaution. — Only  chloride  of  potassium  forms  this  characteristic 
compound ; hence,  if  the  potassium  salt  in  the  solution  is  known  not 
to  be  a chloride,  or  if  its  composition  is  unknown,  a few  drops  of 
hydrochloric  acid  must  be  added,  otherwise  some  of  the  perchloride 
of  platinum  will  be  utilized  for  its  chlorine  only,  the  platinum  being 
wasted.  Thus,  if  nitrate  of  potassium  (KNO3)  be  present,  a few 
drops  of  hydrochloric  acid  enable  the  potassium  to  assume  the  form 
of  chloride  when  the  perchloride  of  platinum  is  added,  nitric  acid 
(HNO3)  being  set  free. 

Memoranda. — Experiments  with  such  expensive  reagents  as  per- 
chloride of  platinum  are  economically  performed  in  watch-glasses, 
drops  of  the  liquids  being  operated  on.  When  the  precipitate  is  long 
in  forming,  it  is  sometimes  of  an  orange-yellow  tint.  If  iodide  of 
potassium  happen  to  be  the  potassium  salt  under  examination,  some 
iodide  of  platinum  (Ptl4)  will  also  be  formed,  giving  a red  color  to 
the  solution,  and  a larger  quantity  of  the  precipitant  (that  is,  the 
precipitating  agent)  be  required. 

Note  on  Nomenclature. — When  distinct  molecules  of  salts  unite 
and  form  a single  crystalline  compound,  the  product  is  termed  a 
double  salt.  The  double  chloride  of  potassium  and  platinum  is  such 
a body. 

Acid  Tartrate  of  Potassium. 

Second  Analytical  Reaction,  — To  a solution  of  any 
salt  of  potassium  add  some  strong  solution  of  tartaric 
acid  (H^C^H^Og),  and  shake  or  well  stir  the  mixture ; a 
white  granular  precipitate  of  acid  tartrate  of  potassium 
(KHC^H^Og)  will  be  formed. 

Limits  of  the  Test. — Acid  tartrate  of  potassium  is  soluble  in  about 
180  parts  of  cold  and  in  6 parts  of  boiling  water.  Hence,  in  applying 
the  tartaric  test  for  potassium,  the  solutions  must  not  be  hot.  Even  if 
cold,  no  percipitate  will  be  obtained  if  the  solutions  are  very  dilute. 
This  test,  therefore,  is  of  far  less  value  than  the  first  mentioned.  The 

* A few  fragments  of  carbonate  of  potassium,  two  or  three  drops  of 
hydrochloric  acid,  and  a small  quantity  of  water,  give  a solution  of 
chloride  of  potassium  at  once,  K^C03-|-2HC1=2KC1+H20-|-C02. 

t By  precApitation  (from  prcecipito^  to  throw  down  suddenly)  is 
simply  m»eant  the  formation  of  particles  of  solid  in  a liquid,  no  matter 
whether  the  s did,  the  precip'tate,  subsides  or  floats. 

6* 


66 


THE  METALLIC  RADICALS. 


acid  tartrate  of  potassium  is  less  soluble  in  diluted  alcohol  than  in 
water ; so  that  the  addition  of  spirit  of  wine  renders  the  reaction 
somewhat  more  delicate. 

Cream  of  Tartar. — The  precipitate  is  the  Bitartrate  or  Acid 
Tartrate  of  Potassium,  though  the  official  preparation  is  not  formed 
in  the  above  manner ; on  the  contrary,  the  acid  is  derived  from  the 
salt,  which  occurs  naturally  in  the  juice  of  many  plants. 

Memorandum. — When  the  tartaric  acid  is  added  to  the  salt  of 
potassium,  and  the  acid  tartrate  formed,  the  acid  whose  chief  elements 
were  previously  with  the  potassium  is  set  free  ; and  in  such  acid  solu- 
tions the  acid  tartrate  is  somewhat  soluble.  To  prevent  loss  on  this 
account,  acid  tartrate  of  sodium,  a salt  tolerably  soluble  in  water, 
may  be  used  as  a test  instead  of  tartaric  acid  (Plunkett).  The 
sodium  uniting  with  the  acidulous  radical,  thus  gives  a neutral  in- 
stead of  an  acid  solution.  But  this  advantage  is  of  less  importance 
from  the  fact  that  more  water  is  introduced  by  the  saturated  solu- 
tion of  acid  tartrate  of  sodium  than  by  a saturated  solution  of  tar- 
taric acid. 

Third  Analytical  Reaction. — The  flame-test.  Dip  the 
looped  end  of  a platinum  wire 'into  a solution  containing 
a potassium  salt,  and  introduce  the  loop  into  a spirit-flame, 
the  flame  of  a mixture  of  gas  and  air,  a blow^pipe  flame,  or 
other  slightly  colored  flame.  A light  violet  or  lavender 
tint  will  be  communicated  to  the  flame,  an  effect  highly’- 
characteristic  of  salts  of  potassium. 

Fourth  Analytical  Fact. — Salts  of  potassium  are  not 
volatile.  Place  a fragment  of  carbonate,  nitrate,  or  any 
other  potassium  salt,  on  a piece  of  platinum  foil,  and  heat 
the  latter  in  the  flame  of  a lamp ; the  salt  may  fuse  to  a 
transparent  liquid  and  flow  freely  over  the  foil,  water  also 
if  present  will  escape  as  steam,  and  black  carbon  be  set 
free  if  the  salt  happen  to  be  of  vegetable  origin  ; but  the 
potassium  compound  itself  will  not  be  vaporized.  This  is 
a valuable  negative  propertv,  as  will  be  evident  when  the 
analytical  reactions  of  ammonium  come  under  notice. 


QUESTIONS  AND  EXERCISES. 

70.  Name  the  sources  of  Potassium. 

71.  Give  the  source,  formula,  and  characters  of  Carbonate  of 
Potassium. 

72.  Distinguish  between  synthetical  and  analytical  reactions. 

73.  How  is  the  official  Liquor  Potassce  prepared  ? 

74.  What  is  the  systematic  name  of  Caustic  Potash  ? 

75.  State  the  chemical  formula  of  Caustic  Potash. 

76.  Construct  an  equation  or  diagram  expressive  of  the  reaction 
between  carbonate  of  potassium  and  slaked  lime, 


SODIUM. 


6Y 


77.  Define  a hydrate. 

78.  What  group  of  atoms  is  characteristic  of  all  carbonates  ? 

79.  Define  the  term  radical. 

80.  How  is  “Sulphurated  Potash”  made,  and  of  what  salts  is  it  a 
mixture  ? 

81.  What  is  the  formula  of  the  acetic  radical — the  radical  of  all 
acetates  ? 

82.  Draw  a diagram  showing  the  formation  of  Acetate  of  Potas- 
sium. 

83.  Give  a general  process  for  the  conversion  of  carbonates  into 
other  salts. 

84.  What  is  the  difference  between  Carbonate  and  Bicarbonate  of 
Potassium  ? How  is  the  latter  prepared  ? 

85.  What  is  the  relation  between  salts  whose  specific  names  end 

in  the  syllable  and  acids  ending  in  “ ^c”  ? 

86.  Draw  out  diagrams  or  equations  descriptive  of  the  formation 
of  Tartrate  of  Potassium  from  the  Acid  Tartrate,  and  Citrate  from 
the  Carbonate  of  Potassium. 

87.  Distinguish  between  a normal  and  an  acid  salt. 

88.  How  is  Iodide  of  Potassium  made  ? Illustrate  the  process  by 
either  diagrams  or  equations. 

89.  Describe  the  appearance  and  chemical  properties  of  iodide  of 
potassium. 

90.  How  much  Iodide  of  Potassium  is  producible  from  1000  grains 
of  Iodine  ? Ans.  1307  grains. 

91.  Give  a method  for  th^  detection  of  iodate  in  iodide  of  potas- 
sium. Explain  the  reaction. 

92.  Has  the  syllable  “ idd^  any  general  signification  in  chemical 

nomenclature  ? • 

93.  What  is  the  difference  between  sulphides,  sulphites,  and  sul- 
phates ? 

94.  Mention  the  chemical  relations  of  Bromide  to  Iodide  of  Potas- 
sium. 

95.  Describe  the  formation  of  Permanganate  of  Potassium,  giving 
equations  or  diagrams. 

96.  How  do  manganate  and  permanganate  of  potassium  act  as 
disinfectants  ? 

97.  Enumerate  the  tests  for  potassium,  explaining  by  diagrams  or 
equations  the  various  reactions  which  occur. 


SODIUM. 

Symbol  Na.  Atomic  weight  23. 

Formula  Na^.  Probable  molecular  weight  46. 

Memoranda. — Most  of  the  sodium  salts  met  with  in  Pharmacy 
are  directly  obtained  from  carbonate  of  sodium,  which  is  now  manu- 
factured on  an  enormous  scale  from  chloride  of  sodium  (common  salt, 
sea-salt  or  bay-salt,  or  rock-salt),  the  natural  source  of  the  sodium 
salts.  When  pure,  salt  [Sodii  Chloridum,  B.  P.  and  U.  S.  P.) 
occurs  “ in  small  white  crystalline  grains,  or  transparent  cubic  crys- 


68 


THE  METALLIC  RADICALS. 


tals,  free  from  moisture the  best  varieties  commonly  contain  a 
little  chloride  of  magnesium  and  sometimes  other  impurities.  Be- 
sides the  direct  and  indirect  use  of  carbonate  of  sodium,  or  carbonate 
of  soda,  as  it  is  commonly  called  in  medicine,  it  is  largely  used  for 
household  cleansing-purposes  under  the  name  of  “ soda,”  and  in  the 
manufacture  of  soap.  Nitrate  of  sodium  also  occurs  in  nature,  but  is 
valuable  for  its  nitric  constituents  rather  than  its  sodium.  Sodium 
is  a constituent  of  about  forty  chemical  or  Galenical  preparations  of 
the  Pharmacopoeias. 

Sodium  is  prepared  by  a process  similar  to  that  for  potassium,  but 
with  less  difficulty.  Its  atom  is  univalent,  Na'. 

Reactions  having  (a)  Synthetical  and  (6)  Analytical 
Interest. 

{a)  Reactions  having  Synthetical  Interest. 

Hydrate  of  Sodium.  Caustic  Soda. 

First  Synthetical  Reaction — The  formation  of  solution 
of  hydrate  of  sodium  or  caustic  soda,  NaHO  {Liquor  Sodse^ 
B.  P.  and  U.  S.  P.).  This  operation  resembles  that  of 
making  solution  of  jiotash  already  described. 

The  practical  student  should  refer  to  the  remarks  made  concern- 
ing solution  of  potash,  applying  them  to  solution  of  soda.  He  may 
perform  the  corresponding  experiments  or  omit  them,  as  he  considers 
he  does  or  does  not  clearly  comprehend  all  they  are  designed  to  teach. 

Na^COg  + Ca2HO  = 2NaHO  + CaCOj 

Carbonate  Hydrate  of  Hydrate  of  Carbonate 

of  sodium.  calcium.  sodium.  of  calcium. 

Pure  Solution  of  Soda,  free  from  any  trace  of  alumina,  may  be 
prepared  by  shaking  in  a Winchester  quart,  once  every  20  or  30 
minutes  for  5 or  6 hours,  14  ozs.  of  crystals  of  carbonate  of  sodium 
and  8 ozs.  of  good  recently  slaked  lime.  The  official  Liquor  Sodce 
is  made  from  28  ounces  of  crystals  of  carbonate  of  sodium,  12  of 
slaked  lime,  and  1 gallon  of  water,  under  precisely  similar  circum- 
stances to  those  detailed  for  Liquor  Potasses  (p.  56).  If  the  solu- 
tion be  evaporated  to  dryness,  and  the  residue  fused  and  poured  into 
moulds,  solid  hydrate  of  sodium  {Soda  Caustica,  B.  P.,  Soda, 
U.  S.  P.)  is  obtained.  Common  and  cheap  caustic  soda  is  now 
largely  employed  in  manufactures.  It  is  a by-product  in  the  prepa- 
ration of  carbonate  of  sodium,  and,  though  highly  useful  as  a chemi- 
cal agent,  is  too  impure  for  use  in  medicine. 

Action  of  Sodium  on  Water. — Sodium,  like  potassium,  decom- 
poses water  with  production  of  hydrate  of  sodium  and  hydrogen,  but, 
unless  the  sodium  is  confined  to  one  spot,  by  placing  it  on  a small 
floating  piece  of  filter-paper,  the  action  is  not  sufficiently  intense  to 
cause  ignition  of  the  escaping  hydrogen.  When  the  latter  does 
ignite,  it  burns  with  a yellow  flame,  due  to  the  presence  of  a little 
vapor  of  sodium. 


SODIUM. 


69 


Second  Synthetical  Reaction. — The  reaction  of  sulphur 
and  carbonate  of  sodium  at  a high  temperature  resembles 
that  of  sulphur  and  carbonate  of  potassium  ; but,  as  the 
product  is  not  used  in  medicine,  the  experiment  may  be 
omitted.  It  is  mentioned  here  to  draw  attention  to  the 
close  resemblance  of  the  potassium  salts  to  those  of  sodium. 

Acetate  of  Sodium. 

Third  Synthetical  Reaction. — Add  the  powder  or  frag- 
ments of  carbonate  of  sodium  (NugCOg)  to  some  strong 
acetic  acid  in  a test-tube  or  evaporating-basin  as  long  as 
effervescence  occurs,  and  then  evaporate  some  of  the  water.* 
When  the  solution  is  cold,  crystals  of  acetate  of  sodium 
(NaC2H30^,3H20)  (Sodii  Acetas^  U.  S.  P.)  will  be  depos- 
ited. A ten  per  cent,  solution  in  distilled  water  forms  the 
“ Solution  of  Acetate  of  Soda,^^  B.  P. 

JSTa.CO^  + = 2NaC,H30,  + H.,0  + CO, 

Carbonate  Acetic  Acetate  of  Water.  Carbonic 

of  sodium.  acid.  sodium.  acid  gas. 

Bicarbonate  of  Sodium. 

Fourth  Synthetical  Reaction. — The  action  of  carbonic 
acid  (H2CO3),  or  carbonic  acid  gas  (CO,)  and  water  (H,0), 
on  carbonate  of  sodium  (Na.,C03).  This  resembles  that  of 
carbonic  acid  on  carbonate  of  potassium,  but  is  applied  in 
a different  manner.  The  result  is  bicarbonate  of  sodium 
(NallCOg)  {Sodii  Bicarbonas  Veiialis^  TJ.  P.  S.). 

Na,C03  + lip  + CO,  = 2NaHC03 

Carbonate  Water.  Carbonic  Bicarbonate 

of  sodium.  acid  gas.  of  sodium. 

Process. — Heat  crystals  of  carbonate  of  sodium  in  a por- 
celain crucible  until  no  more  steam  escapes.  Mix  the  pro- 
duct, in  a mortar,  with  two-thirds  its  weight  of  crystals, 
and  place  the  powder  in  a test-tube  or  small  bottle  into 
which  carbonic  acid  gas  may  be  conveyed  by  a tube  pass- 
ing through  a cork  and  terminating  at  the  bottom  of  the 
vessel.  To  generate  the  carbonic  acid  gas  fill  a test-tube 
having  a small  hole  in  the  bottom  (or  a similar  piece  of 
glass  tubing,  of  which  one  end  is  plugged  b}^  a grooved 
cork)  with  fragments  of  marble,  insert  a cork  and  delivery- 
tube,  and  connect  the  latter  with  the  similar  tube  of  the 

* The  “water”  alluded  to  occurs  in  the  acid,  which,  though  com- 
monly termed  “acetic  acid,”  is  really  a solution  of  that  acid  in  water. 


70 


THE  METALLIC  RADICALS. 


vessel  containing  the  carbonate  of  sodium  by  a piece  of 
India-rubber  tubing.  Now  plunge  the  tube  of  marble  into 
a test-glass,  or  other  vessel,  containing  a mixture  of  one 
part  h3^drochloric  acid  and  two  parts  water,  and  loosen 
the  cork  of  the  carbonate-of-sodium  tube  until  carbonic 
acid  gas,  generated  in  the  marble  tube,  may  be  considered 
to  fill  the  whole  arrangement ; then  replace  the  cork  tightlj^ 
and  set  the  apparatus  aside.  As  the  gas  is  absorbed  by 
the  carbonate  of  sodium,  h^^drochloric  acid  rises  into  the 
marble  tube,  generates  fresh  gas,  which,  in  its  turn,  drives 
back  the  acid  liquid,  and  thus  prevents  the  production  of 
any  more  gas  until  further  absorption  has  occurred.  When 
the  salt  is  wholl}^  converted  into  bicarbonate  (NaHCOg), 
it  will  be  found  to  have  become  damp  through  the  libera- 
tion of  water  from  the  crystallized  carbonate  (Na.^COg, 
lOH^O).  (It  would  be  inconveniently  moist,  even  semi- 
fluid, if  a part  of  the  carbonate  had  not  previously  been 
rendered  anh^^drous.)  The  Sodu  Bicarhonas^  U.  S.  P.,  is 
the  commercial  bicarbonate  purified  from  any  carbonate  or 
traces  of  other  salts  by  introducing  it  into  a percolator  and 
passing  water  through  it  till  the  washings  cease  to  precipi- 
tate a solution  of  sulphate  of  magnesium,  the  bicarbonate 
of  sodium  is  then  removed  from  the  percolator  and  dried 
on  bibulous  paper  in  a warm  place. 

A crystal  of  carbonate  of  sodium  is  carbonate  of  sodium  plus 
water  ; on  heating  it,  more  or  less  of  the  water  is  evolved,  and  anhy- 
drous carbonate  of  sodium  is  partially  or  wholly  produced  [Sodii 
Carbonas  Exsiccata,  U.  S.  P.). 

Na2CO3,10H2O  — lOH^O  = Na^COg 

Crystallized  carbonate  Water.  Dried  carbonate 

of  sodium.  of  sodium. 

Note  on  Nomenclature. — Anhydrous  bodies  (from  a,  a,  and  rScop, 
liudor,  i.  e.  without  water)  are  compounds  from  which  water  has  been 
taken,  but  whose  essential  chemical  properties  are  unaltered.  Salts 
containing  water  are  hydrous  bodies  ; of  these  the  larger  portion  are 
crystalline,  and  their  water  is  then  termed  water  of  crystallization. 
Non-crystalline  hydrous  compounds  were  formerly  spoken  of  as 
hydrated  substances ; hydrates  are,  however,  a distinct  class  of 
bodies,  salts  derived  from  water  by  one-half  of  its  hydrogen  becoming 
displaced  by  an  equivalent  quantity  of  another  radical.  Anhydrides 
arc  compounds  from  which  the  elements  of  water  have  been  removed, 
their  essential  chemical  (acid)  properties  being  thereby  greatly  altered. 
(For  illustrations,  see  Index,  “Anhydrides.”) 

Water  of  Crystallization. — The  water  in  crystallized  carbonate 
of  sodium  is  in  the  solid  condition,  and,  like  ice  and  other  fusible 
substances,  requires  heat  for  its  liquefaction.  Many  salts  (freezing- 


SODIUM. 


n 


mixtures),  when  dissolved  in  water,  give  a very  cold  solution.  This 
is  because  they  and  their  solid  water,  if  they  have  any,  are  then 
converted  into  liquids  which  absorb  heat  from  surrounding  media. 
Take  away  from  water  some  of  its  heat,  the  result  is  ice.  Give  to  ice 
(at  32^  F.)  more  heat  than  it  contains  already,  the  result  is  water 
(still  at  32^  F.).  ( Heat  thus  taken  into  a substance  without  increasing 
its  temperature  is  said  to  become  latent — from  latens,  hiding ; it  is 
no  longer  discoverable  by  the  sense  of  touch  or  the  thermometer. 
The  term  latent  gives  a somewhat  incorrect  idea,  however,  of  the 
process ; for  our  knowledge  of  the  extent  and  readiness  with  which 
one  form  of  force  is  convertible  into  another  renders  highly  probable 
the  assumption  that  heat  is  in  these  cases  converted  into  motion,  the 
latter  enabling  the  particles  of  a solid  to  take  up  the  new  positions 
demanded  by  their  liquid  condition.)  The  only  apparent  difference 
between  ice  and  the  water  in  such  crystals  as  carbonate  of  sodium  is 
that  ice  is  solid  water  in  the  free,  and  water  of  crystallization  solid 
water  in  the  combined  state.  The  former  can  only  exist  at  and  below 
freezing,  the  latter  at  ordinary  temperatures.  In  chemical  formulae, 
the  symbols  representing  water  are  usually  separated  by  a comma 
from  those  representing  salts.  The  crystals  of  acetate  of  sodium 
(of  the  third  reaction)  contain  water  in  this  loose  state  of  combina- 
tion— water  of  crystallization  (Na02H302,3H.^0). 

“ Soda-watery — A solution  of  bicarbonate  of  sodium  in  water 
charged  with  carbonic  acid  gas  under  pressure  constitutes  the  official 
Liquor  So  dee  Effervescens,  B.  P.,  and,  like  the  “potash-water’’  of  the 
shops,  is  a true  medicine,  an  antacid.  Ordinary  “ soda-water,”  how- 
ever, is  in  many  cases  simply  a solution  of  carbonic  acid  gas  in  water, 
and  would  be  more  appropriately  termed  “ aerated  water”  : any 
medicinal  effect  it  may  possess  is  clue  to  the  sedative  influence  of  its 
carbonic  acid  gas  on  the  coats  of  the  stomach.  At  common  tempera- 
tures water  dissolves  about  its  own  volume  of  carbonic  acid  gas, 
both  being  under  equal  pressure.  One  pint  of  the  official  soda-water 
contains  30  grains  of  bicarbonate  of  sodium  and  a pint  of  carbonic 
acid  gas ; but  the  solution  is  under  a pressure  of  seven  atmospheres, 
so  that  seven  pints  of  the  gas  at  ordinary  atmospheric  pressure  are 
required  for  the  quantity  mentioned. 

Solubility  of  Gases  in  Water. — 'Whatever  the  weight  and  volume 
of  a gas  dissolved  by  a liquid  at  ordinary  atmospheric  pressure,  that 
weight  is  doubled  by  double  pressure,  the  two  volumes  of  gas  thereby 
being  reduced  to  one,  trebled  at  treble  pressure,  the  three  volumes 
of  gas  being  reduced  to  one,  quadrupled  at  quadruple  pressure,  the 
four  volumes  of  gas  being  reduced  to  one,  and  so  on.  This  is  a 
general  law  regarding  the  solubility  of  gases  in  liquids  under  given 
temperatures.  An  average  bottle  of  “ soda-water”  contains  about 
four  times  the  weight  of  carbonic  acid  gas  which  can  exist  in  it 
without  artificial  pressure,  so  that  on  removing  its  cork  three  times 
its  bulk  escape,  its  own  bulk  remaining  dissolved. 

Bicarbonate  of  sodium  may  also  be  medicinally  administered  in 
the  form  of  lozenge  {Trochisci  Sodii  Bicarbonatis^  U.  S.  P.). 


72 


THE  METALLIC  RADICALS. 


Tartrate  of  Potasium  and  Sodium. 

Fifth  Synthetical  Reaction, — To  some  hot  strong  solu- 
tion of  carbonate  of  sodium  in  a test-tube  or  larger  vessel 
add  acid  tartrate  of  potassium  till  no  more  effervescence 
occurs  (about  three  parts  to  four  will  be  required) ; when 
the  solution  is  cold,  crystals  of  double  tartrate  of  potas- 
sium and  sodium  {Soda  Tartar ata,,  B.  P.,  Potassii  et  Sodii 
Tartras,^  U.  S.  P.),  the  old  Rochelle  Salt,,  will  be  deposited. 
(KNaC4H^Og,4H^O).  The  crystals  are  usually  halves  of 
right  rhombic  prisms. 

Na,C03  + 2KIIC,H,Oe  = 2KNaC,H,Og  -f  H,0  + CO, 

Carbonate  Acid  tartrate  Double  tartrate  of  Water.  Carbonic 

of  sodium.  of  potassium.  potassium  and  sodium.  acid  gas. 

Formula:  of  Tartrates. 

Tartaric  acid HH  C^H^Og 

Acid  tartrate  of  potassium  . . . KH  C4H40g 

Tartrate  of  potassium  and  sodium  . KNaC^H^Og 

Very  close  analogy  will  be  noticed  in  the  constitution  of  these 
salts.  When  the  other  tartrates  come  under  notice  it  will  be  found 
they  also  have  a similar  constitution. 

Hypochlorite  of  Sodium. 

Sixth  Synthetical  Reaction. — Pass  chlorine  {vide  page  24) 
into  a solution  of  carbonate  of  sodium.  The  result  is  a 
bleaching  and  disinfecting  liquid,  which,  when  made  of  pre- 
scribed strength  (12  ounces  of  carbonate  in  36  of  water, 
charged  by  the  washed  chlorine  from  15  fluidounces  of 
hydrochloric  acid  and  4 ounces  of  black  oxide  of  manga- 
nese), is  the  Solution  of  Chlorinated  Soda  {Liquor  Sodae 
Chloratae)  of  the  British  Pharmacopoeia.  It  is  said  to 
contain  chloride  of  sodium  (NaCl)  and  hypochlorite  of 
sodium  (NaClO),  with  some  undecomposed  bicarbonate  of 
sodium. 

MnO,  + 4IIC1  = MnCl,  -f  2H.,0  + Cl, 

Blk.  oxide  of  Hydrochloric  Chloride  of  Water.  Chlorine, 

manganese.  acid.  manganese. 

Na,CO,  + Cl.,  = NaCI,NaC10  + CO, 

Carbonate  Chlorine.  Chlorinated  Carbonic 

of  sodium.  soda.  acid  gas. 

Liquor  Sodoc  Chlorinatce,  U.  S.  P.,  is  made  by  decomposing  solu- 
tion of  carbonate  of  sodium  by  solution  of  chlorinated  lime,  sp.  gr. 
1.045. 

2Na,C03  + CaCl.,.Ca2C10  = 2(NaClNaC10)  -+-  2CaC03 

Carbonate  Chlorinated  Chlorinated  Carbonate 

of  sodium.  lime.  soda.  of  calcium. 


I 


SODIUM.  73 


other  Sodium  Compounds. 

Synthetical  Reactions  portraying  the  chemistry  of  the  remaining 
official  compounds  (namely,  nitrate,  sulphate,  hyposulphite,  borate, 
arseniate,  and  valerianate  of  sodium)  are  deferred  until  the  several 
acidulous  radicals  of  these  salts  have  been  described. 

Phosphate  of  Sodium. — The  preparation  and  composition  of  this 
salt  will  be  most  usefully  studied  after  bone-ash,  the  source  of  it  and 
other  phosphates,  has  been  described.  Bone-ash  is  phosphate  of  cal- 
cium (see  page  94). 

The  official  Citro-Tartrate  {Sodce  Citro-tartras  Effervescens^ 
B.  P.)  is  a mixture  of  bicarbonate  of  sodium  (17  parts),  citric  acid 
(6),  and  tartaric  acid  (8),  heated  (to  200^  or  220*^)  until  the  particles 
aggregate  to  a granular  condition.  When  required  for  medicinal 
use,  a dose  of  the  mixture  is  placed  in  water ; escape  of  carbonic 
acid  gas  at  once  occurs,  and  an  effervescing  liquid  results. 

Soda  Powders  [Pulveres  Effervescent es,  U.  S.  P.)  are  formed  of 
30  grains  of  bicarbonate  of  sodium  and  25  of  tartaric  acid,  wrapped 
separately  in  papers  of  different  color.  When  mixed  with  water, 
tartrate  of  sodium  results,  a little  bicarbonate  also  remaining. 

In  the  manufacture  of  Carbonate  of  Sodium  from  chloride,  the 
latter  is  first  converted  into  sulphate,  the  sulphate  is  then  roasted 
with  coal  and  limestone,  and  the  resulting  black-ash  lixiviated  [lixi~ 
via,  from  lix,  lye — water  impregnated  with  alkaline  salts  : hence 
lixiviation,  the  operation  of  washing  a mixture  with  the  view  of 
dissolving  out  salts).  The  lye,  evaporated  to  dryness,  yields  crude 
carbonate  of  sodium  (soda-ash).  This  process  will  be  further  de- 
scribed in  connection  with  Carbonates. 


Deliquescence  and  Effiorescence. — The  carbonates  of  sodium  and 
potassium,  chemically  closely  allied,  are  readily  distinguished  physi- 
cally. Carbonate  of  potassium  quickly  absorbs  moisture  from  tlie 
air  and  becomes  damp,  wet,  and  finally  fluid — it  is  deliquescent  [deli- 
quescens,  melting  away).  Carbonate  of  sodium,  on  the  other  hand, 
yields  some  of  its  water  of  crystallization  to  the  air,  the  crystals 
becoming  white,  opaque,  and  pulverulent — it  is  efflorescent  [effio- 
rescens,  blowing  as  a flower). 

Analogy  of  Sodium  salts  to  Potassium  salts. — Other  synthetical 
reactions  might  be  described  similar  to  those  given  under  potassium, 
and  thus  citrate,  iodide,  bromide,  iodate,  bromate,  chlorate,  manga- 
nate,  and  permanganate  of  sodium,  and  many  other  salts  be  formed. 
But  enough  has  been  stated  to  show  how  chemically  analogous 
sodium  is  to  potassium.  Such  analogies  will  constantly  present 
themselves.  In  few  departments  of  knowledge  are  order  and  method 
more  perceptible;  in  few  is  there  as 'much  natural  law,  as  much 
science,  as  in  chemistry. 

Substitution  of  Potassium  and  Sodium  salts  for  each  other. — 
Sodium  salts  being  cheaper  than  potassium  salts,  the  former  may 
sometimes  be  economically  substituted.  That  one  is  employed  rather 


Y4  THE  METALLIC  RADICALS. 

than  the  other,  is  often  merely  a result  due  to  accident  or  fashion. 
But  it  must  be  borne  in  mind  that  in  some  cases  a potassium  salt 
will  crystallize  more  readily  than  its  sodium  analogue,  or  that  a 
sodium  salt  is  stable  when  the  corresponding  potassium  salt  has  a 
tendency  to  absorb  moisture,  or  one  may  be  more  soluble  than  the 
other,  or  the  two  may  have  different  medicinal  effect.  For  these 
or  similar  reasons,  a potassium  salt  has  come  to  be  used  in  medicine 
or  trade,  instead  of  the  corresponding  sodium  salt,  and  vice  versa. 
Whenever  the  acidulous  portion  only  is  to  be  utilized,  the  least 
expensive  salt  of  the  class  would  nearly  always  be  selected. 

(6)  Reactions  liacing  Analytical  Interest, 

1.  The  chie  f o^naly tic al  reaction  for  sodium  is  the  fiame- 
test.  When  brought  into  contact  with  a flame  in  the 
manner  described  under  potassium  (page  66),  an  intensely 
yellow  color  is  communicated  to  the  flame  by  any  salt  of 
sodium.  This  is  highly  cliaracteristic — indeed,  almost  too 
delicate  a test ; for  if  the  point  of  the  wire  be  touched  by 
the  fingers,  enough  salt  (wdiich  is  contained  in  the  moisture 
of  the  hand)  adheres  to  the  wire  to  communicate  a very 
distinct  sodium  reaction.  These  statements  should  be  ex- 
perimentally verified,  the  chloride,  sulphate,  or  any  other 
salt  of  sodium  being  emploj^ed. 

2.  Precipitant  of  Sodium. — Sodium  is  the  only  metal  whose  com- 
mon salts  are  all  soluble  in  water.  Hence  no  ordinary  reagent  can 
be  added  to  a solution  containing  a sodium  salt  which  shall  give  a 
precipitate  containing  the  sodium.  A neutral  or  alkaline  solution  of 
a sodium  salt  gives,  however,  a granular  precipitate  of  antimoniate 
of  sodium  (Na-^H.^Sb^O-,  6H2O)  if  well  stirred  or  shaken  with  a solu- 
tion of  antimoniate  of  potassium  (K2H2Sb207),  but  the  reagent 
precipitates  other  metals,  and  is  liable  to  decompose  and  become 
useless,  and  hence  is  seldom  employed. 

Antimoniate  of  potassium  is  made  by  adding,  gradually,  finely 
powdered  metallic  antimony  to  nitrate  of  potassium  fused  in  a cruci- 
ble so  long  as  deflagration  continues.  The  resulting  mass  is  boiled 
with  a large  quantity  of  water,  the  solution  filtered  and  preserved  in 
a well-stoppered  bottle ; for  the  carbonic  gas  in  the  air  is  rapidly 
absorbed  by  the  solution,  antimonic  acid  being  deposited. 

3.  Sodium  salts,  like  those  of  potassium,  are  not  volatile. 
Prove  this  fact  by  the  means  described  when  treating  of 
the  effect  of  heat  on  potassium  salts  (p.  66). 


AMMONIUM. 


75 


QUESTIONS  AND  EXERCISES. 

98.  How  is  the  official  solution  of  soda  prepared  ? Give  a dia- 
gram or  equation. 

99.  Explain  the  action  of  sodium  or  potassium  on  water.  What 
colors  do  these  elements  respectively  communicate  to  flame  ? 

100.  How  much  bicarbonate  of  sodium  can  be  obtained  from  2240 
pounds  of  crystallized  carbonate  of  sodium  ? Ans.  1316  lbs. 

101.  Acetate  of  sodium:  give  formula,  process,  and  equation. 

102.  Give  a diagram  showing  the  formation  of  bicarbonate  of 
sodium. 

103.  Why  is  a mixture  of  dried  and  undried  carbonate  of  sodium 
employed  in  the  preparation  of  the  bicarbonate  ? 

104.  State  the  difference  between  anhydrous  and  crystallized  car- 
bonate of  sodium. 

105.  Define  the  terms  anhydrous,  hydrous,  hydrate,  anhydride. 

106.  What  do  you  understand  by  ivater  of  crystallization  ? 

107.  What  is  the  nature  of  “ Soda-water  ?” 

108.  How  many  volumes  of  gas  (reckoned  as  at  ordinary  atmo- 
spheric pressure)  are  contained  in  any  given  volume  of  the  British 
official  “ Soda-water  ?” 

109.  What  is  the  general  law  regarding  the  solubility  of  gases  in 
liquids  under  pressure  ? 

110.  What  is  the  systematic  name  of  Rochelle  salt,  and  how  is  the 
salt  prepared  ? 

111.  What  is  the  relation  of  Rochelle  salt  to  cream  of  tartar  and 
tartaric  acid  ? 

112.  Give  the  mode  of  preparation  and  composition  of  solution  of 
chlorinated  soda,  and  express  the  process  by  a diagram. 

113.  How  is  the  granular  effervescing  Citro-tartrate  of  Sodium 
prepared  ? 

114.  Define  Deliquescence,  Efflorescence,  and  Lixiviation. 

115.  What  is  the  general  relation  of  potassium  salts  to  those  of 
sodium  ? 

116.  How  are  sodium  salts  analytically  distinguished  from  those 
of  potassium  ? 


AMMONIUM. 

Symbol  NH^  or  Am.  Atomic  weight  18. 

✓ 

Memoranda. — The  elements  nitrogen  and  hydrogen,  in  the  pro- 
portion of  one  atom  to  four  (NH^),  are  those  characteristics  of  all  the 
compounds  about  to  be  studied,  just  as  potassium  (K)  and  sodium 
(Na)  are  the  characteristic  elements  of  the  potassium  and  sodium 
compounds.  Ammonium  is  a univalent  nucleus,  root,  or  radical,  like 
potassium  or  sodium ; and  the  ammonium  compounds  closely  resemble 
those  of  potassium  or  sodium.  In  short,  if,  for  an  instant,  potassium 
or  sodium  be  imagined  to  be  compounds,  the  analogy  between  these 


76 


THE  METALLIC  RADICALS. 


three  series  of  salts  is  complete.  Yet  ammonium  never  having  been 
isolated,  its  existence  remains  a matter  of  assumption. 

Source. — The  source  of  nearly  all  the  ammoniacal  salts  met  with 
in  commerce  is  ammonia-gas  (NH^)  obtained  in  distilling  coals  in  the 
manufacture  of  ordinary  illuminating  gas.  It  is  doubtless  derived 
from  the  nitrogen  of  the  plants  from  which  the  coal  has  been  pro- 
duced. 

Ammonia. — When  this  gas  (NHg)  comes  into  contact  with  water 
(H2O),  in  the  process  of  washing  and  cooling  coal-gas,  hydrate  of 
ammonium  (NH^HO,  or  AmHO)  is  believed  to  be  formed,  the 
analogue  of  hydrate  of  potassium  (KHO)  or  sodium  (NaHO).  The 
grounds  for  this  belief  are  the  observed  analogy  of  the  well-known 
ammoniacal  salts  to  those  of  potassium  and  sodium,  the  similarity  of 
action  of  solution  of  potash,  soda,  and  ammonia  on  salts  of  most 
metals,  and  the  existence  of  crystals  of  an  analogous  sulphur  salt 
(NH.HS). 

Chloride  of  Ammonium. — The  “ ammoniacal  liquor”  of  the  gas- 
works is  usually  neutralized  by  hydrochloric  acid,  by  which  chloride 
of  ammonium  (sal-ammoniac)  is  produced. 

NH,HO  + HCl  = NH,C1  + H^O  ; 

and  from  this  salt,  purified,  the  others  used  in  pharm’acy  are  directly 
or  indirectly  made.  Chloride  of  ammonium  [Ammonii  Chloridum, 
B.  P.  and  U.  S.  P.)  occurs  “ in  colorless,  inodorous,  translucent  fibrous 
masses,  tough,  and  difficult  to  powder,  soluble  in  water  [1  in  10  is 
the  ‘ Solution  of  Chloride  of  Ammonium,’  B.  P.]  and  in  rectified 
spirit.”  Chloride  of  ammonium  generally  contains  slight  traces  of 
oxychloride  of  iron,  tarry  matter,  and  possibly  chlorides  of  compound 
ammoniums  {vide  “ Artificial  Alkaloids”  in  Index). 

Sidphate  of  Ammonium  (NH4)2,  SO^,  results  when  “ammoniacal 
liquor”  is  neutralized  by  oil  of  vitriol.  It  is  largely  used  as  a con- 
stituent of  artificial  manure  in  England,  and  when  purified  by  recrys- 
tallization is  employed  in  pharmacy  (Ammonii  Sidplias,  U S.  P.). 

Volcanic  Ammonia. — The  purest  form  of  ammonia  is  that  met  with 
in  volcanic  districts,  and  obtained  as  a by-product  in  the  manufacture 
of  borax ; the  crude  boracic  acid  as  imported  contains  about  10  per 
cent,  of  ammonium  salts,  chiefly  sulphate,  and  double  sulphates  of 
ammonium  with  magnesium,  sodium,  and  manganese  (Howard). 

Reactions  haying  {a)  General  (5)  Synthetical,  and  (c) 
Analytical  Interest. 

Ammomiuin-Amalgam.  (?) 

(a)  General  Reaction, — To  forty  or  fifty  grains  of  dry 
rnerciiry  in  a di'y  test-tube,  add  one  or  two  small'pieces  of 
sodium  (freed  from  adhering  naphtha  by  gentle  pressure 
with  a piece  of  filter-paper),  and  amalgamate  by  gently 
warming  the  tube.  To  this  amalgam,  when  cold,  add  some 
fragments  of  chloride  of  ammonium  and  a strong  solution^ 


AMMONIUM. 


11 


of  the  same  salt.  The  sodium  amalgam  soon  begins  to 
swell  and  rapidly  increase  in  bulk,  probablj^  overflowing 
the  tube.  The  light  spongy  mass  produced  is  the  so-called 
ammonium-amalgam,  and  the  reaction  is  usually  adduced 
as  evidence  of  the  existence  of  ammonium;  the  sodium  of 
the  amalgam  unites  with  the  chlorine  of  the  chloride  of  am- 
monium, while  the  ammonium  is  supposed  to  form  an 
amalgam  with  the  mercury.  As  soon  as  formed  the  amal- 
gam gives  off  hydrogen  and  ammonia  gases ; this  decom- 
position is  complete  after  some  minutes,  and  a globule  of 
mercury  alone  remains. 

(b)  Reactions  having  Synthetical  Interest. 

Hydrate  of  Ammonium.  Ammonia. 

First  Synthetical  Reaction, — Heat  a few  grains  of  sal- 
ammoniac  with  about  an  equal  weight  of  hydrate  of  calcium 
(slaked  lime)  damped  with  a little  water  in  a test-tube; 
ammonia  gas  is  given  off,  and  may  be  recognized  by  its 
well-known  odor.  It  is  very  soluble  in  water.  Pass  a 
delivery-tube,  fitted  to  the  test-tube  as  described  for  the 
preparation  of  oxygen  and  hydrogen,  into  a second  test- 
tube,  at  the  bottom  of  which  is  a little  water;  again  heat; 
solution  of  ammonia  will  be  thus  formed. 

2NH^C1  + Ca2HO  = CaCl,  -f  + 2NH3 

Chloride  of  Hydrate  of  Chloride  of  Water,  Ammonia 

ammonium.  calcium.  calcium.  gas. 

Ammonia  gas  is  composed  of  one  atom  of  nitrogen  with  three 
atoms  of  hydrogen;  its  formula  is  NHg;  two  volumes  of  it  contain 
one  volume  of  nitrogen  combined  with  three  atoms  or  volumes  of 
hydrogen.  Its  constituents  have  therefore  in  combining  suffered  con- 
densation to  one-half  their  normal  bulk.  Its  conversion  into  hydrate 
of  ammonium  may  be  thus  shown  : — 

NH3  + H,0  = NH,HO  or  AmHO 

Ammonia  Water.  Hydrate  of  ammonium 

gas.  (ammonia). 

Solutions  of  Ammonia,  prepared  by  this  process  on  a large  scale 
and  in  suitable  apparatus,  are  met  with  in  pharmacy — the  one  (sp. 
gr.  0.891)  containing  32.5  per  cent.,  the  other  (sp.  gr.  0.959),  10  per 
cent.,  by  weight,  of  ammonia  gas,  NH3,  or  66.9  and  20.6  of  ammonia, 
NH^HO  ifLiquor  Ammonioe  Fortior  and  Liquor  Ammonice,  B.  P. 
One  part,  by  measure,  of  the  former,  and  two  of  water  form  the 
latter).  On  the  large  scale,  bottles  are  so  arranged  in  a series  as 
to  condense  all  the  ammonia  evolved  during  the  operation.  Aqua 
Ammonioe  Fortior,  U.  S.  P.,  sp.  gr.  0.900,  contains  26  per  cent,  of 
^ ammonia  gas.  Aqua  Ammonioe,  U.  S.  P.,  has  a sp.  gr.  of  0.960. 

I* 


THE  METALLIC  RADICALS. 


78 

Note. — When  water  is  mixed  with  strong  solution  of  ammonia,  ex- 
pansion occurs.  Thus,  calculating  from  the  stated  specific  gravities 
of  the  official  solutions,  3000  parts  by  measure  of  the  Liquor  Am- 
monice  weigh  2877  parts  (959  X 3) ; whereas  1000  parts  by  measure 
of  the  Liquor  Ammonice  Fortior  (weighing  891  parts)  and  2000 
measures  of  water  (weighing  2000)  weigh  2891  parts.  Apparently 
1000  volumes  of  the  strong  solution  of  ammonia  with  2000  volumes 
of  water  yield  3000  volumes  of  mixture,  and  14  parts  by  weight,  or 
15  volumes  to  spare,  total  3015  volumes — an  expansion  of  about  half 
of  one  (.5)  per  cent. 

Acetate  of  Ammonium. 

Second  Synthetical  Reaction. — To  acetic  acid  and  water 
in  a test-tube  add  })owdered  commercial  carbonate  (acid 
carbonate  and  carbamate)  of  ammonium  until  effervescence 
ceases  ; the  resulting*  liquid,  made  of  prescribed  strength,  is 
the  official  solution  of  Acetate  of  Ammonium  (NH^C2H302) 
{Liquor  Ammonii  Acetatis.,  U.  S.  P.). 

(NH.HCO^O^NH.NII^CO^  + 

Acid  carbonate  and  carbamate  Acetic  acid.  Acetate  of 

of  ammonium.  ammonium. 

+ 2H.,0  + SCO, 

Water.  Carbonic  acid  gas. 

Carbonates  of  Ammonium. 

Commercial  carbonate  of  ammonium  is  made  by  heating  a mix- 
ture of  chalk  and  sal-ammoniac;  chloride  of  calcium  (CaC^)  is  pro-, 
duced,  ammonia  gas  (NH3)  and  water  (H2O)  escape,  and  the  ammo- 
niacal  carbonate  distils,  or  rather  sublimes,*  in  cakes  [Ammonii 
Carbonas,  B.  P.  and  U.  S.  P.).  The  best  form  of  apparatus  to  em- 
ploy is  a retort  with  a short  wide  neck  and  a cool  receiver.  On  the 
large  scale  the  retort  is  usually  iron  and  the  receiver  earthenware  or 
glass ; on  the  small  scale  glass  vessels  are  employed.  The  salt  is 
purified  by  resublimation  at  a low  temperature  ; 150^  F.  is  said  to 
be  sufficient. 

This  salt,  the  empirical  formula  of  which  is  N^H^gCgOg,  is  probably 
a mixture  of  two  molecules  of  acid  carbonate  or  bicarbonate  of  am- 
moniuih  (2NH^HC03)  and  one  of  a salt  termed  carbamate  of  ammo- 
nium (NH^NH2C02).  The  latter  belongs  to  an  important  class  of 
salts  known  as  carbamates,  but  it  is  the  only  one  of  interest  to  the 
pharmacist.  Cold  water  extracts  it  from  the  commercial  carbonate 
of  ammonium,  leaving  the  acid  carbonate  of  ammonium  undissolved, 
if  the  amount  of  liquid  used  be  very  small.  In  water  carbamate 
soon  changes  into  neutral  carbonate  of  ammonium, 

Nn,NH2C02  + II2O  = (NHj2C03or  Am2C03 ; 

* Sublimation  (from  suhlimis^  high).  Vaporization  of  a solid  sub- 
stance by  heat,  and  its  condensation  on  an  upper  and  cooler  part  of 
the  vessel  or  apparatus  in  which  the  operation  is  performed. 


AMMONIUM. 


19 


SO  that  an  aqueous  solution  of  commercial  carbonate  of  ammonium 
contains  both  acid  carbonate  and  neutral  carbonate  of  ammonium. 
If  to  such  a solution  some  ordinary  solution  of  ammonia  be  added,  a 
solution  of  neutral  carbonate  of  ammonium  is  obtained ; and  this 
is  the  common  reagent  always  found  on  the  shelves  of  the  analytical 
laboratory. 

AmllCOg  4-  AmHO  = Am.COg  + H,0. 

Neutral  carbonate  of  ammonium  is  the  salt  formed  on  adding  strong 
solution  of  ammonia  to  the  commercial  carbonate  in  preparing  a 
pungent  mixture  for  toilet  smelling-bottles ; but  it  is  unstable,  and 
on  continued  exposure  to  air  is  reduced  to  a mass  of  crystals  of  the 
acid  carbonate  or  bicarbonate  of  ammonium.  Bicarbonate  of  am- 
monium (NH4HCO3)  is  also  produced  on  passing  carbonic  acid  gas 
into  an  aqueous  solution  of  commercial  carbonate. 

According  to  Divers,  the  sublimed  product  of  the  first  distillation 
of  chalk  and  sal-ammoniac  is  a mixture  of  carbamate  and  carbonate 
of  ammonium,  the  latter  losing  some  ammonia  gas  on  redistillation, 
and  carbamate  with  bicarbonate  forming  the  resulting  commercial 
salt.  Dr.  Divers  considers  that  the  salt  now  met  with  in  trade  con- 
tains one  molecule  of  acid  carbonate  to  one  of  carbamate,  and  not 
two  of  the  former  to  one  of  the  latter,  as  was  the  case  when  the  ana- 
lyses were  made  from  which  the  foregoing  formulae  were  deduced. 

Sal  Volatile  {Spiritus  Ammonice  Aromaticus,  B.P.  and  U.  S.P.) 
is  a spirituous  solution  of  ammonia  (AmHO),  neutral  carbonate  of 
ammonium  (Am^COg),  and  the  oils  of  nutmeg  and  lemon  (and  laven- 
der, U.  S.  P.).  Fetid  spirit  of  ammonia  [Spiritus  Ammonice  Foeti- 
dus,  B.  P.)  is  an  alcoholic  solution  of  the  volatile  oil  of  assafoetida 
mixed  with  solution  of  ammonia.  “ Solution  of  Carbonate  of  Am- 
monia,” B.  P.,  is  formed  by  dissolving  half  an  ounce  of  the  salt  in 
ten  ounces  of  water.  Spiritus  Ammonice,  U.  S.  P.,  is  an  alcoholic 
solution  of  ammonia. 


Citrate,  Phosphate,  and  Benzoate  of  Ammonium. 

Third  Synthetical  Reaction. — To  solution  of  citric  acid 
(HgCjjH.Oy  or  HgCi)  add  solution  of  ammonia  (AmHO) 
until  the  liquid  is  neutral  to  test-paper  ; the  product  is  So- 
lution of  Citrate  of  Animonium  (AmgCi)  Liquor  Ammonise 
Citratis.^  B.  P.). 

Phosphate  of  Ammonium  (Am2HP04)  [Ammonice,  Phosphas, 
B.  P.)  and  Benzoate  of  Ammonium  (AmC7H302)  [Ammonii  Ben- 
zoas,  U.  S.  P.)  are  also  made  by  adding  solution  of  ammonia  to 
phosphoric  acid  (H3PO4)  and  benzoic  acid  (HO7H-O2)  respectively, 
evaporating  (keeping  the  ammonia  in  slight  excess  by  adding  more 
of  its  solution),  and  setting  aside  for  crystals  to  form.  The  official 
Solution  of  Acetate  of  Ammonium  could  be  made  in  the  same  way  ; 
but,  when  prepared  with  Carbonate  of  Ammonium,  the  liquid  re- 
mains charged  with  carbonic  acid,  and  has  a less  vapid  flavor. 


80 


THE  METALLIC  RADICALS. 


H3CAO, 

Citric 

acid. 

+ 

SAmllO 

Ammonia. 

Citrate  of 
ammonium. 

3IT2O 

Water. 

H3P0, 

Phosphoric 

acid. 

+ 

2AmHO 

Ammonia. 

= Am2HP04 

Phosphate  of 
ammonium. 

+ 

2H2O 

Water. 

H0,H50, 

Benzoic 

acid. 

+ 

AmHO 

Ammonia. 

= AmC^H^O.^ 

Benzoate  of 
ammonium. 

+ 

H2O 

Water. 

Phospliate  of  ammonium  occurs  in  transparent  colorless  prisms,  solu- 
ble in  water,  insoluble  in  spirit ; benzoate  in  crystalline  plates,  solu- 
ble in  water  and  in  spirit. 

Ammonii  lodidum^  U.  S.  P.,  is  made  by  decomposing  the  two 
bodies  iodide  of  potassium  and  sulphate  of  ammonium,  which  give 
iodide  of  ammonium  and  sulphate  of  potassium ; the  latter  salt  is 
separated  by  adding  alcohol  to  the  cooled  solution,  when,  by  reason 
of  its  insolubility  in  alcohol,  it  crystallizes  out,  and  the  separated 
solution  of  iodide  of  ammonium  is  then  evaporated  to  dryness. 

Bromide  of  Ammonium  [Ammonii  Bromidum,  B.  P.  and 
U.  S P.)  will  be  noticed  in  connection  with  Hydrobromic  Acid  and 
Other  Bromides. 


Oxalate  of  Ammonium. 

Fourth  Synthetical  Reaction. — To  a nearly^  boiling  solu- 
tion of  1 part  of  oxalic  acid  in  about  8 of  water  add 
carbonate  of  ammonium  until  the  liquid  is  neutral  tt) 
test-paper,  filter  while  hot,  and  set  aside  for  crystals 
(NH^)2C20^,H20)  to  form.  The  mother-liquor  is  useful  as 
a reagent  in  analysis  : 1 of  the  salt  in  40  of  water  consti- 
tutes “Solution  of  Oxalate  of  Ammonia,’’  B.  P. 

2H,C,0,  + N,H,,C303  = 2(NH,),C,0,  + SCO,  + 2H,0 

Oxalic  Carbonate  of  Oxalate  of  Carbonic  Water, 

acid.  ammonium.  ammonium.  acid  gas. 


Sulphydrate  of  Ammonium. 

Fifth  Synthetical  Reaction. — Pass  sulphuretted  hydro- 
gen gas  (H2S)  through  a small  quantity  of  solution  of  am- 
monia in  a test-tube,  until  a portion  of  the  liquid  no  longer 
causes  a white  precipitate  in  solution  of  sulphate  of  mag- 
nesium (Epsom  salt)  ; the  product  is  solution  of  sulphy- 
drate (or  sulphide)  of  ammonium  (NH^HS),  the  “ Solution 
of  Sulphide  of  Ammonium”  of  the  British  Pharmacopoeia, 
a most  valuable  chemical  reagent,  as  will  presently  be 
a !>  parent. 

NHJIO  + n^S  = Nil, IIS  -f  H^O. 


SULPHURETTED  HYDROGEN. 


81 


Solution  of  Sulphide  of  Ammonium  f B.  P.,  is  made  by  passing 
tlie  gas  prepared  in  the  apparatus  described  below  into  3 fluidounces 
of  solution  of  ammonia  [Liquor  Ammonice)  so  long  as  the  gas 
continues  to  be  absorbed,  then  adding  2 more  ounces  of  solution  of 
ammonia,  and  preserving  the  solution  in  a well-stoppered  bottle. 

Sulphuretted  hydrogen  is  a compound  of  noxious  odor ; 
hence  the  above  operation,  and  many  others,  described 
further  on,  in  which  this  gas  is  indispensable,  can  only  be 
performed  in  the  open  air,  or  in  a fume-cupboard,  a chamber 
so  contrived  that  deleterious  gases  and  vapors  shall  escape 
into  a chimney  in  connection  with  the  external  air.  In  the 
above  experiment,  the  small  quantity  of  gas  required  can 
be  made  in  a test-tube,  after  the  manner  of  hydrogen  itself. 
To  two  or  three  fragments  of  sulphide  of  iron  (FeS),add 
water  and  then  sulphuric  acid  ; the  gas  is  at  once  evolved, 
and  may  be  conducted  by  a tube  into  the  solution  of 
ammonia. 

FeS  + H,SO,  = H,S  + FeSO,. 

The  iron  remains  dissolved  in  the  water  in  the  state  of  sulphate  of 
iron. 

Crystals  of  sulpliy  dr  ate  of  ammonium  (NH^HS)  may  be  obtained 
on  bringing  ammonia  gas  (NH3)  and  sulphuretted  hydrogen  (H2S) 
together  at  a low  temperature.  They  are  soluble  in  water  without 
decomposition. 

Sulphuretted-hydrogen  Apparatus, — As  no  heat  is  neces- 
sary in  making  sulphuretted  hydrogen,  the  test-tube  of  the 
foregoing  operation  may  be  advantageously  replaced  by  a 
bottle,  especially  when  larger  quantities  of  the  gas  are 
required.  In  anal3Tical  operations,  the  gas  should  be 
purified  by  passing  it  through  water  contained  in  a second 
bottle. 

The  most  convenient  arrangement  for  experimental  use 
is  prepared  as  follows:  Two  common  wide-mouth  bottles 
are  selected,  the  one  having  a capacity  of  about  half  a pint, 
the  other  a quarter  pint;  the  former  ma}^  be  called  the 
generating-bottle,  the  latter  the  wash-bottle.  Fit  two  corks 
to  the  bottles.  Through  each  cork  bore  two  holes  hy  a round 
file  or  other  instrument,  of  such  a size  that  glass  tubing  of 
about  the  diameter  of  a quill  pen  shall  fit  them  tightly. 
Through  one  of  the  holes  in  the  cork  of  the  generating- 
bottle  pass  a funnel-tube,  so  that  its  extremity  may  nearly 
reach  the  bottom  of  the  bottle.  Such  “funnel-tubes’’  may^ 
be  purchased  at  the  usual  shops ; or,  if  the  student  has 
access  to  a table-blowpq)e,  and  the  advantage  of  a tutor  to 


82 


THE  METALLIC  RADICALS. 


direct  his  operations,  they  may  be  made  by  himself.  To 
the  other  hole  adapt  a piece  of  tubing,  6 inches  long,  and 
bent  in  the  middle  to  a right  angle.  A similar  “ elbow- 
tube’’  is  fitted  to  one  of  the  holes  in  the  cork  of  the  wash- 
bottle,  and  another  elbow-tube,  one  arm  of  which  is  long 
enough  to  reach  to  near  the  bottom  of  the  wash-bottle, 
fitted  to  the  other  hole.  Removing  the  corks,  two  or 
three  ounces  of  water  are  now  poured  into  each  bottle,  an 
ounce  or  two  of  sulphide  of  iron  put  into  the  generating- 
bottle,  and  the  corks  replaced.  The  elbow-tube  of  the 
generating-bottle  is  now  attached  hy  a short  piece  of 
India-rubber  tubing  to  the  long-armed  elboAv-tube  of  the 
wash-bottle,  so  that  gas  coming  from  the  generator  may 
pass  through  the  water  in  the  wash-bottle.  The  delivery- 
tube  of  the  wash-bottle  is  then  lengthened  by  attaching  to 
it,  by  India-rubber  tubing,  a straight  piece  of  glass  tubing, 
three  or  four  inches  long.  The  apparatus  is  now  ready  for 
use.  Strong  sulphuric  acid  is  poured  down  the  funnel-tube 
in  small  quantities  at  a time,  until  brisk  effervescence  is 
established,  and  more  added  from  time  to  time  as  the 
evolution  of  gas  becomes  slow.  The  gas  passes  through 
the  tubes  into  the  wash-bottle,  where,  as  it  bubbles  up 
through  the  water,  an}^  trace  of  sulphuric  acid,  or  other 
matter  mechanically  carried  over,  is  arrested,  and  thence 
flows  out  at  the  deliver3'-tube  into  any  vessel  or  liquid  that 
may  be  placed  there  to  receive  it.  The  generator  must  be 
occasionally  dismounted,  and  the  sulphate  of  iron  washed 
out. 

Luting  [lutum,  mud). — If  the  corks  of  the  above  apparatus  are 
sound,  and  tube-holes  well  made,  no  escape  of  gas  Avill  occur.  If 
rough  corks  have  been  employed,  or  the  holes  are  not  cylindrical, 
linseed-meal  lute  may  be  rubbed  oA^er  the  defective  parts.  The  lute 
is  prepared  by  mixing  linseed-meal  Avith  Avater  to  the  consistence  of 
dough.  A neat  appearance  may  be  given  to  the  lute  by  gently  rub- 
bing a well-wetted  finger  over  its  surface. 

(c)  Reactions  having  Analytical  Interest  {Tests,) 

First  Analytical  Reaction. — To  a solution  of  any  salt  of 
ammonium  (the  chloride,  for  example)  in  a test-tube  add 
solution  of  caustic  soda  (or  solution  of  potash,  or  a little 
slaked  lime) ; ammonia  gas  is  at  once  evolved,  recognized 
by  its  well-knoAvn  odor. 

NII^CT  + NallO  = NII3  + 11,0  + NaCl. 


SULPHURETTED  HYDROGEN. 


83 


Though  ammonium  itself  cannot  exist  in  the  free  state,  its  com- 
pounds are  stable.  Ammonia  is  easily  expelled  from  those  compounds 
by  action  of  the  stronger  alkalies,  caustic  potash,  soda,  or  lime.  As 
a matter  of  exercise,  the  student  should  here  draw  out  equations  in 
which  acetate  {NH^C2H302),  sulphate  (Am2S04),  nitrate  (NH^NOj) 
or  any  other  ammoniacal  salt  not  already  having  the  odor  of  am- 
monia, is  supposed  to  be  under  examination ; also  representing  the 
use  of  the  other  hydrates,  potash  (KHO)  or  slaked  lime  (Ca2HO). 

The  odor  of  ammonia  gas  is  perhaps  the  best  means  of 
recognizing  its  presence ; but  the  following  tests  are  also 
occasionally  useful.  Into  the  test-tube  in  which  the  am- 
monia gas  is  evolved  insert  a glass  rod  moistened  with 
hydrochloric  acid  (that  is,  with  the  solution  of  hydro- 
chloric acid  gas,  conveniently  termed  hydrochloric  acid, 
the  Acidam  Hydrochloricum  of  the  Pharmacopseias) ; white 
fumes  of  chloride  of  ammonium  will  be  produced. 

NH3  -f  HCl  = NH,C1. 

Hold  a piece  of  moistened  red  litmus  paper  in  a tube  in 
which  ammonia  gas  is  present;  the  red  color  will  be 
changed  to  blue. 

Test-papers. — Litmus  (B.  P.)  is  a blue  vegetable  pigment,  pre- 
pared from  various  species  of  Roccella  lichen,  exceedingly  sensitive 
to  the  action  of  acids,  which  turn  it  red.  When  thus  reddened,  alka- 
lies (potash,  soda,  and  ammonia)  and  other  soluble  hydrates  readily 
turn  it  blue.  The  student  should  here  test  for  himself  the  delicacy 
of  this  action  by  experiments  with  paper  soaked  in  solutions  of  litmus 
and  dipped  into  very  dilute  solutions  of  acids,  acid  salts  (KHC^H^Og 
e.g.),  alkalies,  and  such  neutral  salts  as  nitrate  of  potassium,  sul- 
phate of  sodium,  or  chloride  of  ammonium. 

Tincture  of  Litmus. — 1 ounce  of  litmus  is  macerated  for  two  days 
in  10  fluidounces  of  proof  spirit,  and  the  solution  poured  off  from  in- 
soluble matter. 

Blue  litmus  paper  is  unsized  white  paper  steeped  in  tincture  of 
litmus  and  dried  by  exposure  to  the  air.  Red  litmus  paper  is 
unsized  white  paper  steeped  in  tincture  of  litmus  which  has  been 
previously  reddened  by  the  addition  of  a very  minute  quantity  of 
sulphuric  acid,  and  dried  by  exposure  to  the  air. 

Turmeric  paper,  similarly  prepared  from  tincture  of  turmeric  (1  of 
turmeric  root  or  rhizome  to  6 of  rectified  spirit,  macerated  for  seven 
days),  is  occasionally  useful  as  a test  for  alkalies,  which  turn  its 
yellow  to  brown  ; acids  do  not  affect  it. 

Second  Analytical  Reaction. — To  a few  drops  of  a solu- 
tion of  an  ammonium  salt  add  a drop  or  two  of  hydrochloric 
acid  and  a like  small  quantity  of  solution  of  perchloride  of 
platinum  (PtClJ  ; a yellow  crystalline  precipitate  of  the 
double  chloride  of  platinum  and  ammonium  (PtC1^2NH^Cl) 


84 


THE  METALLIC  RADICALS. 


will  be  produced,  similar  in  appearance  to  the  corresponding 
salt  of  potassium,  the  remarks  concerning  which  (p.  65) 
are  equally  applicable  to  the  precipitate  under  notice. 

Third  Analytical  Reaction, — To  a moderately  strong 
solution  of  an  ammonium  salt  add  a strong  solution  of 
tartaric  acid,  and  shake  or  well  stir  the  mixture ; a white 
granular  precipitate  of  acid  tartrate  of  ammonium  will  be 
formed. 


For  data  from  which  to  draw  out  an  equation  representing  this 
action,  see  the  remarks  and  formulae  under  the  analogous  salt  of 
potassium  (p.  65). 

Fourth  Analytical  Fact, — Evaporate  a few  drops  of  a 
solution  of  an  ammonium  salt  to  dryness,  or  place  a frag- 
ment of  a salt  in  the  solid  state  on  a piece  of  platinum 
foil,  and  heat  in  a flame  ; the  salt  is  volatilized.  As 

already  noticed,  the  salts  of  potassium  and  sodium  are 
fixed  under  these  circumstances,  a point  of  difference  of 
which  advantage  wdll  frequently  be  taken  in  analysis.  A 
porcelain  crucible  may  often  be  advantageously  substituted 
for  platinum  foil  in  experiments  on  volatilization. 

A wire-triangle  may  be  used  in  supporting  crucibles.  It  is  made 
by  placing  three  (5  or  6 inch)  pieces  of  wire  in  the  form  of  a triangle 
and  then  twisting  each  pair  of  ends  together  through  half  the  length 
of  the  wires.  A piece  of  tobacco-pipe  stem  (about  2 inches)  is  some- 
times placed  in  the  centre  of  each  wire  before  twisting,  the  transfer- 
ence of  any  metallic  matter  to  the  sides  of  the  crucible  being  thus 
prevented. 


Practical  Analysis, 

With  regard  to  those  experiments  which  are  useful  rather  as  means 
of  detecting  the  presence  of  potassium,  sodium,  and  ammonium,  than 
as  illustrating  the  preparation  of  salts,  the  student  should  proceed 
to  apply  them  to  certain  solutions  of  any  of  the  salts  of  potassium, 
sodium,  and  ammonium,  with  the  view  of  ascertaining  which  metal 
is  present ; that  is,  proceed  to  practical  analysis.*  A little  thought 

* Such  solutions  are  prepared  in  educational  laboratories  by  a 
tutor.  They  should,  under  other  circumstances,  be  mixed  by  a friend, 
as  it  is  not  desirable  to  know  previously  what  is  contained  in  the 
substance  about  to  be  analyzed. 

The  analysis  of  solutions  containing  only  one  salt  serves  to  impress 
the  memory  with  the  characteristic  tests  for  the  various  metals  and 
other  radicals,  and  familiarize  the  mind  with  chemical  principles. 
Medical  students  seldom  have  time  to  go  further  than  this.  More 
thorough  analytical  and  general  chemical  knowledge  is  only  acquired 


POTASSIUM,  SOUIUxM,  AMMONIUM.  S5 

will  enable  him  to  apply  these  reactions  in  the  most  suitable  order 
and  to  the  best  advantage  for  the  contemplated  purpose ; but  the 
following  arrangements  are  perhaps  as  good  as  can  be  devised: — 

DIRECTIONS  FOR  APPLYING  THE  FOREGOING  ANALYTICAL  RE- 
ACIONS  TO  THE  ANALYSIS  OF  AN  AQUEOUS  SOLUTION  OF 
A SALT  OF  OTsTE  OF  THE  METALS,  POTASSIUM,  SODIUM, 

Ammonium. 

Add  caustic  soda  to  a small  portion  of  the  solution  to 
be  examined,  and  warm  the  mixture  in  a test-tube ; the 
odor  of  ammonia  gas  at  once  reveals  the  presence  of  an 
ammonium  salt. 

If  ammonium  be  not  present,  apply  the  perchloride-of- 
platinum  test ; a yellow  precipitate  proves  the  presence  of 
potassium. 

(It  will  be  observed  that  potassium  can  only  be  detected 
in  the  absence  of  ammonium,  salts  of  the  latter  radical 
giving  similar  precipitates.) 

The  flame-test  is  sufficient  for  the  recognition  of  sodium. 


DIRECTIONS  FOR  APPLYING  THE  FOREGOING  ANALYTICAL  RE- 
ACTIONS TO  THE  ANALYSIS  OF  AN  AQUEOUS  SOLUTION  OF 
SALTS  OF  OTsTE,  TWO,  OH  ALL  THBEE  OF  THE  ALKALI 
METALS. 

Commence  by  testing  a small  portion  of  the  solution  for 
an  ammonium  salt.  If  present,  make  a memorandum  to 
that  effect,  and  then  proceed  to  get  rid  of  the  ammoniacal 
compound  to  make  way  for  the  detection  of  potassium: 
advantage  is  here  taken  of  the  volatility  of  ammonium 
salts  and  the  fixity  of  those  of  potassium  and  sodium. 
Evaporate  the  original  solution  to  dryness  in  a small 
basin,  transfer  the  solid  residue  to  a porcelain  crucible, 
and  heat  the  latter  to  a low  redness,  or  until  dense  white 
fumes  (of  ammoniacal  salts)  cease  to  escape.  This  opera- 
tion should  be  conducted  in  a fume-cupboard,  to  avoid 
contamination  of  the  air  of  the  apartment.  When  the  cru- 

by  working  on  such  mixtures  of  bodies  as  are  met  with  in  actual 
practice,  beginning  with  solutions  which  may  contain  any  or  all  the 
members  of  a group.  Hence  in  this  manual,  two  Tables  of  short 
directions  for  analyzing  are  given  under  each  group.  Pharmaceutical 
students  should  follow  the  second  Table. 

8 


86 


THE  METALLIC  RADICALS. 


cible  is  cold,  dissolve  out  the  solid  residue  with  a small 
quantity  of  hot  water,  and  test  the  solution  for  potassium 
by  the  perchloride-of-platinum  test,  and  for  sodium  by  the 
flame  test. 

If  ammonium  is  proved  to  be  absent,  the  original  solu- 
tion may,  of  course,  be  at  once  tested  for  potassium  and 
sodium. 

Flame-test. — The  violet  tint  imparted  to  flame  by  potassium  salts 
may  be  seen  when  masked  by  the  intense  yellow  color  due  to  sodium, 
if  the  flame  be  observed  through  a piece  of  dark-blue  glass,  a medium 
which  absorbs  the  yellow  rays  of  light. 

Note  on  Nomenclature. — The  operations  of  evaporation  and 
heating  to  redness,  or  ignition,  are  frequently  necessary  in  analysis, 
and  are  usually  conducted  in  the  above  manner.  If  vegetable  or 
animal  matter  be  also  present,  carbon  is  set  free,  and  ignition  is  ac- 
companied by  carbonization  ; the  material  is  said  to  char.  When 
all  carbonaceous  matter  is  burnt  off,  the  crucible  being  slightly  in- 
clined and  its  cover  removed  to  facilitate  combustion,  and  mineral 
matter,  or  ash,  alone  remains,  the  operation  of  incmeration  has 
been  effected. 

Note  on  the  Classification  of  Elements. — The  compounds  of  po- 
tassium, sodium,  and  ammonium  have  many  analogies.  Their  car- 
bonates, phosphates,  and  most  other  salts  are  soluble  in  water.  The 
atoms  of  the  radicals  themselves  are  univalent — that  is,  displace  or 
are  displaced  by  one  atom  of  hydrogen.  In  fact,  they  constitute  by 
their  similarity  in  properties  a distinct  group  or  family.  All  the 
elements  thus  naturally  fall  into  classes — a fact  that  should  con- 
stantly be  borne  in  mind,  and  evidence  of  which  should  always  be 
sought.  It  would  be  impossible  for  the  memory  to  retain  the  details 
of  chemistry  without  a system  of  classification  and  leading  princi- 
ples. Classification  is  also  an  important  feature  in  the  art  as  well 
as  in  the  science  of  chemistry ; for  without  it  practical  analysis  could 
not  be  undertaken.  The  classification  adopted  in  this  volume  is 
founded,  as  far  as  possible,  on  the  quantivalence  of  the  elements,  but 
chiefly  on  their  analytical  relations. 


QUESTIONS  AND  EXERCISES. 

117.  Why  are  ammoniacal  salts  classed  with  those  of  potassium 
and  sodium  ? 

118.  Mention  the  sources  of  the  ammonium  salts. 

119.  Describe  the  appearance  and  other  characters  of  Chloride  of 
Ammonium. 

120.  (live  the  formula  of  Sulphate  of  Ammonium. 

121.  Adduce  evidence  of  the  existence  of  ammonium. 


BARIUM. 


87 


122.  How  are  the  official  Solutions  of  Ammonia  prepared  ? Hive 
diagrams. 

123.  How  is  the  official  Solution  of  Acetate  of  Ammonium  pre 
pared  ? 

124.  What  is  the  composition  of  commercial  Carbonate  of  Ammo- 
nium ? 

125.  Define  suhlimation. 

126.  What  ammoniacal  salts  are  contained  in  Spmtus  Ammontoe 
Aromaticus  ? 

127.  Give  diagrams  or  equations  illustrating  the  formation  of 
Citrate,  Phosphate,  and  Benzoate  of  Ammonium. 

128.  Give  the  formula  of  Oxalate  of  Ammonium. 

129.  Show  how  hydrate  of  ammonium  may  be  converted  into  sul- 
phydrate. 

130.  Describe  the  preparation  of  Sulphuretted  Hydrogen  gas. 

131.  Enumerate  and  explain  the  tests  for  ammonium. 

132.  How  is  potassium  detected  in  a solution  in  which  ammonium 
has  been  found  ? 

133.  Give  equations  illustrating  the  action  of  hydrate  of  sodium 
on  acetate  of  ammonium  ; hydrate  of  potassium  on  sulphate  of  ammo- 
nium ; and  hydrate  of  calcium  on  nitrate  of  ammonium. 

134.  What  are  the  effects  of  acids  and  alkalies  on  litmus  and  tur- 
meric ? 

135.  Describe  the  analysis  of  an  aqueous  liquid  containing  salts  of 
potassium,  sodium,  and  ammonium. 

136.  What  meanings  are  commonly  assigned  to  the  terms  evapo- 
ration, ignition,  carbonization,  and  incineration  ? 

137.  Write  a short  article  descriptive  of  the  analogies  of  potas- 
sium, sodium,  and  ammonium,  and  their  compounds. 


BARIUM,  CALCIUM,  MAGNESIUM. 


These  three  elements  have  many  analogies.  Their  atoms  are 
bivalent. 


BARIUM. 


Symbol  Ba.  Atomic  weight  137. 

The  analytical  reactions  only  of  this  metal  are  of  interest  to  the 
general  student  of  pharmacy.  The  chloride  (BaCl2)  (Chloride  of 
Barium,  B.  P.  and  IJ.  S.  P.,  and  “ Solution  of  Chloride  of  Barium,” 
1 in  10  of  water,  B.  P.)  and  nitrate  (Ba2N03)  are  the  soluble  salts 
in  common  use  in  analysis ; and  these  and  others  are  made  by  dis- 
solving the  native  carbonate  (BaCOg),  Barii  Carbonas,  U.  S.  P., 
the  mineral  witherite,  in  acids,  or  by  heating  the  other  common  natu- 
ral compound  of  barium,  the  sulphate,  heavy  ivhite  or  heavy  spOrV 
(BaSO^),  with  coal — 

BaSO,  + C4  = 4CO  + BaS, 


88 


THE  xMETALLIC  RADICALS. 


and  dissolving  the  resulting  snlpliide  in  acids.  When  the  nitrate  is 
strongly  heated,  it  is  decomposed,  the  oxide  of  barium  or  baryta 
(BaO)  remaining.  Baryta,  on  being  moistened,  assimilates  the  ele- 
ments of  water  with  great  avidity,  and  yields  hydrate  of  barium, 
(Ba2HO).  The  latter  is  tolerably  soluble,  giving  baryta-water; 
and  from  this  solution  crystals  of  hydrate  of  barium  are  obtained  on 
evaporation. 

The  operations  above  described  may  all  be  performed  in  test-tubes 
and  small  porcelain  crucibles  heated  by  the  gas-flame.  Quantities 
of  1 oz.  to  1 lb.  require  a coke-furnace. 

Peroxide  of  barium  (BaO.^)  is  formed  on  passing  air  over  heated 
baryta.  By  the  action  of  dilute  hydrochloric  acid  it  yields  solution 

peroxide  of  hydrogen  (H^,02)  or  oxygenated  water. 

Quantivaleyice. — The  atom  of  barium  is  bivalent,  Ba". 

Reactions  having  Analytical  Interest  (Tests). 

First  Analytical  Reaction. — To  the  solution  of  any  soluble 
salt  of  barium  (nitrate  or  chloride,  for  example)  add  dilute 
sulphuric  acid ; a white  precipitate  is  obtained.  Set  the 
test-tube  aside  for  two  or  three  minutes,  and  when  some 
of  the  precipitate  has  fallen  to  the  bottom  pour  away  most 
of  the  supernatant  liquid,  add  strong  nitric  acid,  and  boil ; 
the  precipitate  is  insoluble. 

The  production  of  a white  precipitate  by  sulphuric  acid,  insoluble 
even  in  hot  nitric  acid,  is  highly  characteristic  of  barium.  The  name 
of  this  precipitate  is  sulphate  of  barium  ; its  formula  is  BaSO^. 

Antidotes. — In  cases  of  poisoning  by  soluble  barium  salts,  any 
sulphates,  such  as  those  of  magnesium  and  sodium  (Epsom  salt, 
Glauber’s  salt,  alum),  would  be  obvious  antidotes. 

Second  Analytical  Reaction. — To  a barium  solution  add 
solution  of  the  j^ellow  chromate  of  potassium  (KfirO^)] 
a pale  yellow  precipitate  (BaCrOJ  falls.  Add  acetic  acid 
to  a portion  of  the  chromate  of  barium  ; it  is  insoluble. 
Add  hydrochloric  or  nitric  acid  to  another  portion  ; it  is 
soluble. 

“ Neutral  Chromate.^’ — The  red  chromate  (or  bichromate)  of  po- 
tassium (K.^CrO^.  CrOg)  must  not  be  used  in  this  reaction,  or  the 
barium  will  be  only  imperfectly  precipitated  ; for  the  red  salt  gives 
rise  to  the  formation  of  free  acid,  in  which  chromate  of  barium  is  to 
some  extent  soluble  : — 

K^CrO^,  Cr03.+  2BaCl2  + II^O  = 2BaCrO,  + 2KC1  + 2I1C1. 

Yellow  chromate  is  obtained  on  adding  carbonate  of  potassium,  in 
small  quantities  at  a time,  to  a hot  solution  of  the  red  chromate 
until  eflervescence  ceases ; a little  more  red  chromate  is  then  added 
to  insure  decomposition  of  any  slight  excess  of  carbonate  of  potas- 
sium. 


KgCrO,,  CrOg  + K2CO3  = 2K2CrO,  4-  CO^, 


BARIUM. 


89 


For  analytical  purposes  solution  of  a neutral  chromate  is  still 
more  readily  prepared  by  simply  adding  solution  of  ammonia  to  solu- 
tion of  red  chromate  of  potassium,  until  the  liquid  turns  yellow,  and, 
after  stirring,  smells  of  ammonia. 

K^CrO,,  Cr03  + 2NH,HO  = 2KNH,CrO,  + H,0. 

Other  Analytical  Beactions. — To  a barium  solution  add 
a soluble  carbonate  (carbonate  of  ammonium  (Am^COg) 
will  generally  be  rather  more  useful  than  others) ; a white 

precipitate  of  carbonate  of  barium  (BaCOg)  results. To 

more  of  the  solution  add  an  alkaline  phosphate  or  arseni- 
ate  (phosphate  of  sodium  (Na^HPOJ  is  the  most  common 
of  these  chemically  analogous  salts,  but  phosphate  of  am- 
monium (Am.^HPOJ  or  arseniate  (Am2HAsOj  will  subse- 
quently have  the  preference) ; white  phosphate  of  barium 
(BaHPOJ,  insoluble  in  pure  water  but  slightly  soluble  in 
aqueous  solutions  of  some  salts,  or  arseniate  of  barium 
(BallAsO^),  both  soluble  even  in  acetic  and  other  weak 
acids,  are  precipitated. To  another  portion  add  oxa- 

late of  ammonium  (Am5^C20J ; white  oxalate  of  barium 
(BaC20J  is  precipitated,  soluble  in  strong  acids,  and  spar- 
ingly so  in  acetic  acid. The  silico-fluoride  of  barium 

(BaSiPg)  is  insoluble,  and  falls  readily  if  an  equal  volume 
of  spirit  of  wine  be  added  to  the  solution  under  examina- 
tion after  the  addition  of  hydrofluosilicic  acid  (H^SiFg.) 

Barium  salts,  moistened  with  hydrochloric  acid,  impart 

a greenish  color  to  flame. 

Mem. — Good  practice  will  be  found  in  writing  out  equations  de- 
scriptive of  each  of  the  foregoing  reactions. 


QUESTIONS  AND  EXEKOISES. 

138.  What  is  the  quantivalence  of  barium  ? 

139.  Write  down  the  formulae  of  oxide,  hydrate,  chloride,  nitrate, 
carbonate,  and  sulphate  of  barium ; and  state  how  these  salts  are 
prepared. 

140.  Describe  the  preparation  of  peroxide  of  hydrogen. 

141.  Which  of  the  tests  for  barium  are  most  characteristic  ? Give 
an  equation  of  the  reactions. 

142.  Name  the  antidote  in  cases  of  poisoning  by  soluble  barium 
salts,  and  explain  its  action. 

8* 


90 


THE  METALLIC  RADICALS. 


CALCIUM. 

Symbol  Ca.  Atomic  weight  40. 

Calcium  compounds  form  a large  proportion  of  the  crust  of  our 
earth.  Carbonate  of  calcium  is  met  with  as  chalk,  marble,  lime- 
stone, calc-spar,  etc.,  the  sulphate,  as  gypsum  or  plaster  of  Paris 
(“  Plaster  of  Paris,  native  sulphate  of  calcium — CaS04,  2H2O — 
deprived  of  water  by  heat.” — B.  P.),  and  alabaster,  the  silicate  in 
many  minerals,  the  fluoride  of  calcium  as  fluor-spar.  The  phosphate 
is  also  a common  mineral.  The  element  itself  is  only  isolated  with 
great  difficulty.  The  atom  of  calcium  is  bivalent,  Ca". 

Reactions  having  Synthetical  Interest. 

Chloride  of  Calcium. 

First  Synthetical  Reaction, — To  some  hydrochloric  acid 
add  carbonate  of  calcium  (chalk,  or,  the  purer  form,  white 
marble.  Mariner  Album,,  B.  P.  and  IT.  S.  P.)  (CaCOg)  until 
effervescence  ceases,  filter;  solution  of  chloride  of  calcium 
(CaCl^),  the  most  common  soluble  salt  of  calcium,  is  formed. 

CaCOg  + 2HC1  = CaCl^  + H^O  + CO^ 

Carbonate  of  Hydrochloric  Chloride  of  Water.  Carbonic 

calcium.  acid.  calcium.  acid  gas. 

This  solution  contains  carbonic  acid,  and  will  give  a precipitate 
of  carbonate  of  calcium  on  the  addition  of  lime-water.  It  may  be 
obtained  quite  neutral  by  well  boiling  before  filtering  off  the  excess 
of  marble.  It  is  a serviceable  test-liquid  in  analytical  operations. 

Solution  of  chloride  of  calcium  evaporated  to  a syrupy  consistence 
readily  yields  crystals.  These  are  extremely  deliquescent.  The  solu- 
tion, evaporated  to  dryness,  and  the  white  residue  strongly  heated, 
gives  solid  anhydrous  chloride  of  calcium  in  a porous  form.  The 
resulting  agglutinated  lumps  ( Calcii  Chloridum,  B.  P.  and  U.  S.  P.) 
are  much  used  for  drying  gases,  and  for  freezing  certain  liquids  from 
water.  The  salt  is  soluble  in  alcohol.  One  part  in  ten  of  water 
constitutes  a useful  test-liquid,  “ Solution  of  Chloride  of  Calcium,” 
B.  P.  Four  parts  in  five  of  water  forms  the  “ Solution  (saturated) 
of  Chloride  of  Calcium,”  B.  P. 

Marble  often  contains  ferrous  carbonate  (FeC02), 
in  the  above  pirocess  becomes  converted  into  ferrous  chloride, 
rendering  the  chloride  of  calcium  impure  : — 

FeCOg  -f  2nCl  = FeCl^  + H,0  + CO^ 

Ferrous  Hydrochloric  Ferrous  Water.  Carbonic 

carbonate.  acid.  chloride.  acid  gas. 

If  absolutely  pure  chloride  of  calcium  be  required,  a few 
drops  of  the  solution  should  be  poured  into  a test-tube  or 


CALCIUM. 


91 


test-glass,  diluted  with  water,  and  examined  for  iron  (by 
adding  sulphydrate  of  ammonium,  which  gives  a black 
precipitate  with  salts  of  iron),  and,  if  the  latter  is  present, 
hypochlorite  of  calcium  (in  the  form  of  chlorinated  lime) 
and  slaked  lime  should  be  added  to  the  remaining  bulk  of 
the  liquid,  and  the  whole  boiled  for  a few  minutes,  wliereby 
iron  (as  ferric  hydrate)  is  thus  precipitated  ; on  filtering,  a 
pure  solution  of  chloride  of  calcium  is  obtained: — 


Ferrous 

chloride. 


+ Ca2C10  + 4CaH.p,  + 

Hypochlorite  Hydrate  of 

of  calcium.  calcium. 


= 2(Fe,6HO) 

Fen-io 

hydrate. 


+ 5CaCI, 

Chloride 
of  calcium. 


2H,0 

Water. 


This  is  the  official  process,  and  may  be  imitated  on  the 
small  scale  after  adding  a minute  piece  of  iron  to  a frag- 
ment of  the  marble  before  dissolving  in  acid. 


The  names,  formulae,  and  reactions  of  these  compounds  of  iron  will 
be  best  understood  when  that  metal  comes  under  treatment. 


Oxide  of  Calcium  (Quick  Lime). 

Second  Synthetical  Reaction, — Place  a small  piece  of 
chalk  in  a strong  grate-fire  or  furnace  and  heat  until  a trial 
fragment,  chipped  off  from  time  to  time  and  cooled,  no 
longer  effervesces  on  the  addition  of  acid  ; caustic  lime, 
CaO  {Calx,^  B.  P.  and  XJ.  S.  P.),  remains. 

CaC03  = CaO  + CO, 

Carbonate  of  Oxide  of  Carbonic 

calcium  (chalk).  calcium  (lime).  acid  gas. 

Note. — Etymologically  considered,  this  action  is  anylytical  (dm- 
^uco,  analuo,  I resolve)  and  not  synthetical  sunthesis,  a 

putting  together) ; but  conventionally  it  is  synthetical,  and  not 
analytical ; for  in  this,  the  usual  sense,  and  the  sense  in  which  the 
words  are  used  throughout  this  book,  synthesis  is  the  application  of 
chemical  action  with  the  view  of  producing  something,  analysis  the 
application  of  chemical  action  with  the  view  of  finding  out  the  com- 
position of  a substance.  In  the  etymological  view  of  the  matter 
there  is  scarcely  an  operation  performed  either  by  the  analyst  or  by 
the  manufacturer  but  includes  both  analysis  and  synthesis. 

Lime-kilns. — On  the  large  scale  the  above  operation  is  carried  on 
in  what  are  termed  lime-kilns  [Kiln,  Saxon,  cyln,  from  cylene,  a 
furnace). 

Hydrate  of  Calcium  (Slaked  Lime). 

Slaked  Lime, — When  cold,  add  to  the  lime  about  half 
its  weight  of  water,  and  notice  the  evolution  of  steam  and 


92 


THE  METALLIC  RADICALS. 


other  evidence  of  strong  action  ; the  product  is  slaked  lime 
or  hydrate  of  calcium  (Ca2H0)  {Galcis  hydras^  B.  P.), 
with  whatever  slight  natural  impurities  the  lime  might 
contain.  The  slaking  of  hard  or  stony^^  lime  may  be 
accelerated  by  using  hot  water. 

CaO  -p  H^O  = Ca2H0 

Lime.  Water.  Hydrate  of  calcium 

(slaked  lime). 

Lime-water. — Place  the  hydrate  of  calcium  in  about  a 
hundred  times  its  weight  of  water:  in  a short  time  a satu- 
rated solution,  known  as  lime-water  {Liquor  Calais^  B.  P. 
and  U.  S.  P.),  results.  It  contains  about  IG  grains  of 
hydrate  of  calcium  (Ca2H0),  equivalent  to  about  11  or  12 
grains  of  lime  (CaO),  in  one  pint. 

Strong  Solution  of  Lime. — Slaked  lime  is  much  more  soluble  in 
aqueous  solution  of  sugar  than  in  pure  water.  The  Liquor  Calcis 
Saccharatus,  B.  P.,  is  such  a solution,  containing  2 ounces  of  sugar 
and  188  grains  of  hydrate  of  calcium  (Ca2H0),  equivalent  to  142 
grains  of  lime  (CaO),  in  1 pint.  It  is  a more  efficient  precipitant  of 
hydrates  and  carbonates  than  lime-water.  The  official  process  is  as 
follows : Mix  1 ounce  of  lime  and  2 of  sugar  by  trituration  in  a 
mortar.  Transfer  the  mixture  to  a bottle  containing  1 pint  of  water, 
and,  having  closed  this  with  a cork,  shake  it  occasionally  for  a few 
hours.  Finally  separate  the  clear  solution  with  a siphon  and  keep 
it  in  a stoppered  bottle. 

Solutions  of  hydrate  of  calcium  absorb  carbonic  acid  gas  on  ex- 
posure to  air,  a semicrystalline  precipitate  of  carbonate  being 
deposited.  When  the  saccharated  solution  is  heated,  there  is  preci- 
pitated a compound  of  three  molecules  of  lime  with  one  of  sugar. 

Carbonate  of  Calcium. 

Third  Synthetical  Reaction. — To  a solution  of  chloride 
of  calcium  add  excess  of  carbonate  of  sodium,  or  about 
5 parts  of  dry  chloride  to  13  of  carbonate;  a white  preci- 
pitate of  carbonate  of  calcium  ( Galcii  Garhonas  Praecijpi- 
tata.^  U.  S.  P.),  (CaCOg)  results.  If  the  solutions  of  the 
salts  be  made  hot  before  admixture,  and  the  whole  set  aside 
for  a short  time,  the  particles  aggregate  to  a greater  extent 
than  when  cold  water  is  used,  and  the  product  is  finely 
granular  or  slightly  crystalline.  The  official  variety  is 
thus  prepared. 

CaCl,  + Na,C03  = CaC03  + 2NaCl 

Chloride  of  Carbonate  of  Carbonate  of  Chloride  of 
calcium.  sodium.  calcium.  sodium. 

Collect  and  purify  this  Precipitated  Ghalk  b}"  pouring 
the  mixture  into  a paper  cone  supported  by  a funnel,  and, 


CALCIUM. 


93 


when  the  liquid  has  passed  through  the  filter,  pour  water 
over  the  precipitate  three  or  four  times  until  the  whole  of 
the  chloride  of  sodium  is  washed  away.  This  operation  is 
termed  washing  a precipitate.  When  dry  {;mde  Index, 
“ Drying  precipitates’’)  the  precipitate  is  fit  for  use. 

Filtering-paper,  or  hibulous-paper  (from  hiho,  to  drink),  is  simply 
good  unsized  paper  made  from  the  best  white  rags — white  blotting- 
paper,  in  fact,  of  unusually  good  quality.  Students’  or  analysts’ 
filters,  on  which  to  collect  precipitates,  are  round  pieces  of  this  paper, 
from  three  to  six  inches  in  diameter,  twice  folded,  and  then  opened 
out  so  as  to  form  a hollow  cone.  Square  pieces  are  rounded  by  scissors 
after  folding.  The  cone  is  supported  by  a glass  or  earthenware  funnel. 

Washing-bottle. — Precipitates  are  best  washed  by  a fine  jet  of 
water  directed  on  to  the  different  parts  of  the  filter.  A common 
narrow-necked  bottle  of  about  half-pint  capacity  is  fitted  with  a cork  ; 
two  holes  are  bored  through  the  cork,  the  one  for  a glass  tube  reach- 
ing to  the  bottom  of  the  bottle  within,  and  externally  bent  to  a 
slightly  acute  angle,  the  other  for  a tube  bent  to  a slightly  obtuse 
angle,  the  inner  arm  terminating  just  within  the  bottle.  The  outer 
arms  may  be  about  3 inches  in  length.  The  extremity  of  the  outer 
arm  continuous  with  the  long  tube  should  be  previously  drawn  out 
to  a fine  capillary  opening  by  holding  the  original  tube,  before  cut- 
ting, in  a flame,  and,  when  soft,  gently  pulling  the  halves  away  from 
each  other  fintil  the  heated  portion  is  reduced  to  the  thinness  of  a 
knitting-needle.  The  tube  is  now  cut  at  the  thin  part  by  a file,  and 
the  sharp  edges  rounded  off  by  placing  in  a flame  for  a second  or 
two.  The  outer  extremity  of  the  shorter  tube  should  also  be  made 
smooth  in  the  flame.  The  apparatus  being  put  together,  and  the 
bottle  nearly  filled  with  water,  air,  blown  through  the  short  tube  by 
the  lungs,  forces  water  out  in  a fine  stream  at  the  capillary  orifice. 

Decantation. — Precipitates  may  also  be  washed  by  allowing  them 
to  settle,  pouring  off  the  supernatant  liquid,  agitating  with  water, 
again  allowing  to  settle,  and  so  on.  This  is  washing  by  decantation 
[de,  from,  canthus,  an  edge).  If  a stream  of  liquid  flowing  from  a 
basin  or  other  vessel  exhibits  any  tendency  to  run  down  the  outer 
side  of  the  vessel,  it  should  be  guided  by  a glass  rod  placed  against 
the  point  whence  the  stream  emerges. 

If  the  vessel  be  too  large  to  handle  with  convenience,  the  wash- 
water  may  be  drawn  off  by  a siphon.  A siphon  is  a tube  of  glass, 
metal,  gutta-percha,  or  India-rubber,  bent  into  the  form  of  a Y or  U, 
filled  with  water,  and  inverted ; one  end  immersed  in  the  wash-water, 
and  the  other  allowed  to  hang  over  the  side  of  the  vessel ; so  long 
as  the  outer  orifice  of  the  instrument  is  below  the  level  of  the  liquid 
in  the  vessel,  so  long  will  that  liquid  flow  from  within  outwards  until 
the  vessel  be  empty.* 

* The  nature  of  the  action  of  a syphon  is  simple.  The  column  of 
water  in  the  outer  limb  is  longer,  and  therefore  heavier,  than  the 
column  of  similar  area  in  the  inner  limb.  (The  length  of  the  inner 
limb  must  be  reckoned  from  the  surface  of  the  liquid,  the  portion 


94 


THE  METALLIC  RADICALS. 


Prepared  carbonate  of  calcium  [Creta  Prceparata,  B.  P.  and 
U.  S.  P.)  is  merely  washed  chalk  [Creta,  B.  P.  and  U.  S.  P.)  or 
loliiting,  only  that  in  Pharmacy  fashion  demands  that  the  chalk  be 
in  little  conical  lumps,  about  the  size  of  thimbles,  instead  of  in  the 
larger  rolls  characteristic  of  “ whiting.”  Wet  whiting  pushed,  por- 
tion by  portion,  through  a funnel,  and  each  separately  dried,  gives 
the  conventional  Creta  Prceparata.  Its  powder  is  amorphous. 

Testa  Prceparata,  U.  S.  P.,  is  powdered  oyster-shell,  similarly 
treated.  It  is  an  inferor  kind  of  prepared  chalk. 

Phosphate  of  Calcium. 

Fourth  Synthetical  Reaction. — Digest  bone-ash  (bones 
burnt  in  an  open  crucible  with  free  access  of  air  till  all 
animal  and  carbonaceous  matter  has  been  removed — im- 
pure phosphate  of  calcium  {Os  Ustum^  B.  P.))  with  nearly 
twice  its  weight  of  hydrochloric  acid  (diluted  with  three 
or  four  times  its  bulk  of  water)  in  a test-tube  or  larger 
vessel ; the  phosphate  is  dissolved. 


Ca32PO,  + 4HC1  = CaHSPO, 


Phosphate  of 
calcium  (impure). 


Hydrochloric 
acid. 


Acid  phosphate 
of  calcium. 


+ 2CaCI, 

Chloride  of 
calcium. 


Dilute  with  water,  filter,  boil,  and  w^hen  cold  add  excess 
of  solution  of  ammonia ; the  phosphate  of  calcium,  now 
pure  (Galcis  Phosphas^  B.  P.;  Calcii  Phosphas  Precipitata^ 
U.  S.  P.),  is  reprecipitated  as  a light  white  amorphous 
powder.  After  well  washing,  the  precipitate  should  be 
dried  over  a water-bath  {ride  Index),  or  at  a temperature 
not  exceeding  512^,  to  prevent  undue  aggregation  of  the 
particles. 

Ca32PO,  -f  4AmCl 

Phosphate  Chloride  of 
of  calcium  ammonium, 
(pure). 


CaH,2PO^  + 

Acid  phosphate 
of  calcium. 


2CaCl,  + 4AmHO 

Chloride  Ammonia, 

of  calcium. 

+ 4II,p 

Water. 


Bone-ash  or  bone-earth  contains  small  quantities  of  car- 
bonate and  sulphide  of  calcium.  These  are  decomposed  in 
the  above  process  by  the  acid,  chloride  of  calcium  being 
formed;  on  boiling  the  mixture,  carbonic  acid  gas  and  sul- 

below  the  surface  playing  no  part  in  the  operation).  Being  heavier, it 
naturally  falls  by  gravitation,  the  liquid  in  the  shorter  limb  instantly 
following,  because  pressed  upwards  by  the  air.  The  air,  be  it  ob- 
served, exerts  a similar  amount  of  pressure  on  the  liquid  in  the  outer 
limb:  in  short,  atmospheric  pressure  causes  the  retention  of  liquid 
in  the  instrument,  while  gravitation  determines  the  direction  of  the 
flow. 


CALCIUM. 


95 


pliuretted  hydrogen  gas  are  evolved.  Any  carbonaceous 
or  siliceous  matter,  etc.,  is  removed  by  filtration.  In  bones 
the  phosphate  of  calcium  is  always  accompanied  by  a small 
quantity  of  an  allied  substance,  phosphate  of  magnesium ; 
a trace  of  fiuoride  of  calcium  (CaF2)  is  also  present. 

Bone-black^  or  Animal  Charcoal  {Garbo  Animalis^  B.  P. 
and  U.  S.  P.),  is  the  residue  obtained  on  subjecting  dried 
bones  (Os,  IJ.  S.  P.)  to  a red  heat  without  access  of  air. 
The  operation  may  be  imitated  by  heating  a few  fragments 
of  bone  in  a covered  porcelain  crucible  in  a fume-chamber 
until  smoke  and  vapor  cease  to  be  evolved.  Purified  Ani- 
mal Charcoal  {Garbo  Animalis  FuriJicatus^B,  P.  and  U.  S. 
P.)  is  obtained  by  digesting  animal  charcoal  (16  parts)  in 
hydrochloric  acid  (10  parts)  and  water  (20  parts)  in  a warm 
place  for  a day  or  two,  filtering,  thoroughly  washing,  drying 
over  a water-bath,  and  igniting  the  product  in  a closely 
covered  crucible.  The  reaction  is  the  same  as  that  just 
described ; that  is  to  say,  the  acid  removes  the  phosphate 
of  calcium  from  the  carbon  of  animal  charcoal  by  forming 
soluble  acid  phosphate  and  chloride  of  calcium. 

Wood  Charcoal  ( Garbo  Ligni^  B.  P.  and  U.  S.  P.)  is  wood 
similarly  ignited  without  access  of  air. 

Decolorizing  power  of  Animal  Charcoal. — Animal  char- 
coal, in  small  fragments,  is  the  material  emploj^ed  in  de- 
colorizinsf  solutions  of  common  brown  su^arwith  the  view 
of  producing  white  lump  sugar.  Its  power  and  the  nearly 
equal  power  of  an  equivalent  quantity  of  the  purified  va- 
riety may  be  demonstrated  on  solution  of  litmus  or  log- 
wood. 

Phosphate  of  Sodium — Phosphate  of  calcium  is  con- 
verted into  phosphate  of  sodium  {Sodii  Phosphas.,  U.  S.  P.) 
(Na2HP04,12H20)  as  follows:  Mix,  in  a mortar,  3 ounces 
of  ground  bone-earth  with  1 fluidounce  of  sulphuric  acid; 
set  aside  for  twentj^-four  hours  to  promote  reaction  ; mix 
in  about  3 ounces  of  water,  and  put  in  a warm  place  for 
two  days,  a little  water  being  added  to  make  up  for  that 
lost  by  evaporation  ; stir  in  another  3 ounces  of  water,  warm 
the  whole  for  a short  time,  filter,  and  wash  the  residual 
sulphate  of  calcium  on  the  filter  to  remove  adhering  acid 
phosphate  of  calcium;  concentrate  the (the  liquid 
portion),  which  is  a solution  of  acid  phosphate  of  calcium, 
to  about  3 ounces,  filter  again,  if  necessary,  add  solution 
of  (about  4^  ounces  of  crystals  of)  carbonate  of  sodium  to 
the  hot  filtrate  until  a precipitate  (a  phosphate  of  calcium, 


96 


THE  METALLIC  RADICALS. 


CaHPO^),  ceases  to  form,  and  the  fluid  is  faintly  alkaline ; 
Alter,  evaporate,  and  set  aside  to  ciystallize. 

Phosphate  of  sodium  occurs  ‘‘  in  transparent  colorless 
rhombic  prisms,  terminated  b^-  four  converfying  planes, 
efflorescent,  tasting  like  common  salt.’’  One  part  in  ten 
of  water  constitutes  ‘‘  Solution  of  Phosphate  of  Soda,” 
B.  P.  This  is  an  official  as  well  as  the  ordinary  process. 
The  following  equations  show  the  two  decompositions 
which  occur  during  the  operations: — 

Ca32PO,  + 2H,SO,  = CaH,2PO,  -f  2CaSO, 

Phosphate  Sulphuric  Acid  phosphate  Sulphate  of 

of  calcium  acid.  of  calcium.  calcium. 

CaH,2PO,  + Na^CO,  = Na,HPO,  + H,0 

Acid  phosphate  Carbonate  Phosphate  of  Water, 

of  calcium.  of  sodium.  sodium. 

+ CO,  + CaHPO, 

Carbonic  Phosphate 

acid  gas.  of  calcium. 

Ordinary  phosphate  of  sodium  (Na^HPO^,  12H.^O)  efflo- 
resces rapidly  in  the  air  until  nearly  half  its  water  has 
escaped,  when  it  has  a permanent  composition  represented 
by  the  formula  Na^HPO^, 

Hypochlorite  of  Calcium. 

Fifth  Synthetical  Reaction Pass  chlorine,  generated  as 

already  described,  into  damp  slaked  lime  contained  in  a 
piece  of  wide  tubing,  open  at  the  opposite  end  to  that  in 
which  the  deliveiy-tube  is  fixed.  (A  test-tube,  the  bottom 
of  which  has  been  accidentally  broken,  is  very  convenient 
for  such  operations.)  The  product  is  ordinaiy  bleaching- 
powder^  said  to  be  a mixture  of  hypochlorite  and  chloride 
of  calcium,  commonly  called  chloride  of  lime^  Calx  chlo- 
rata^  B.  P.  {Calx  Chlorinata^  U.  S.  P.). 

MnO^  -f  4HC1  = MnCl^  + 2H,0  + Cl, 

Black  oxide  Hydrochloric  Chloride  of  Water.  Chlorine.^, 

of  manganese.  acid.  manganese.  N 

2CaH,0,  + 2C1,  :=  2H,0  + CaCl,0,  , CaCl,  \ 

Hydrate  of  Chlorine.  Water.  Hypochlorite  Chloride  j 

calcium.  of  calcium,  of  calcium. 

Chlorinated  lime,  exposed  to  air  and  moisture,  as  in  disinfecting 
the  air  of  sick  rooms,  slowly  yields  hypochlorous  acid  (HCIO).  Free 
hypochlorous  acid  soon  breaks  up  into  w’ater,  chloric  acid  (IICIO-J, 
and  free  chlorine.  Chloric  acid  is  also  unstable,  decomposing  into 
oxygen,  water,  chlorine,  and  perchloric  acid  (HCIO4),  The  small 
quantity  of  hypochlorous  acid,  diffused  through  an  apartment  when 


CALCIUM. 


91 


bleaching-powder  is  exposed  thus,  yields  fourteen-fifteenths  of  its 
chlorine  in  the  form  of  chlorine  gas — one  of  the  most  efficient  of 
known  disinfectants. 

Bleaching-liquor,, — Digest  chlorinated  lime  in  water,  in 
which  the  bleaching  compound  is  soluble,  filter  from  the 
undissolved  lime,  and  test  the  bleaching-powers  of  the 
clear  liquid  by  adding  a few  drops  to  a decoction  of  log- 
wood slightly  acidulated.  One  pound  of  this  bleaching- 
powder,  shaken  several  times  during  three  hours,  with  1 
gallon  of  water,  forms  Solution  of  Chlorinated  Lime 
{Liquor  Galcis  Chloratse^  B.  P.). 

Gummate  of  Calcium, 

Gummate  of  Calcium  is  the  only  official  calcium  salt 
that  remains  to  be  noticed.  This  compound  is,  in  short, 
arahin^  the  ordinary  Gum-Acacia,  or  Gum-Arabic  {Acacise 
Gummi^  B.  P.,  and  U.  S.  P.),  a substance  too  well  known 
to  need  description.  A solution  of  gum-arabic  in  water 
(Mucilago  Acaciw,  B.  P.  and  LT.  S.  P.)  yields  a white  pre- 
cipitate of  oxalate  of  calcium  on  the  addition  of  solution 
of  oxalate  of  ammonium.  Or  a piece  of  gum  burnt  to  an 
ash  in  a porcelain  crucible  yields  a calcareous  residue, 
which,  dissolved  in  dilute  acids,  affords  characteristic  re- 
actions with  any  of  the  following  analytical  reagents  for 
calcium.  The  gummic  radical  may  be  precipitated  as 
opaque  gelatinous  gummate  of  lead  by  the  addition  of 
solution  of  oxyacetate  of  lead  {Liquor  Flumbi  Suhacetatis^ 
B.  P.)  to  an  aqueous  solution  of  gum.  These  statements 
may  be  experimentally  verified  by  the  practical  student. 

Tragacanth  {Tragacantha,  B.  P.  and  U.  S.  P.)  is  usually  consid- 
ered to  be  a mixture  of  soluble  gum  or  arabin  and  a variety  of  cal- 
cium gum  insoluble  in  water,  termed  hassorin : Guibourt  thought 
it  to  be  gelatinoid.  With  water  a gelatinous  mucilage  is  formed 
[Mucilago  Tragacanthce,  B.  P.  and  U.  S.  P.). 

Reactions  having  Analytical  Interest  (Tests). 

First  Analytical  Reaction. — Add  sulphuric  acid,  highly 
diluted,  to  a calcium  solution  contained  in  a test-tube  or 
small  test-glass;  sulphate  of  calcium  (CaSO^,  211^0)  is 
formed,  but  is  not  precipitated,  it  being,  unlike  sulphate  of 
barium,  slightly  soluble  in  water. 

Solution  of  Sulphate  of  Calcium. — A quarter  of  an  ounce  of  that 
(dried)  form  of  sulphate  of  calcium  known  as  plaster  of  Paris  (CaSO^) 
9 


98 


THE  METALLIC  RADICALS. 


digested  in  one  pint  of  water  for  a short  time,  with  occasional  shak- 
ing, and  the  mixture  filtered,  yields  the  official  test-liquid  termed 
“ Solution  of  Sulphate  of  Lime,”  B.  P.  About  400  parts  of  the  solu- 
tion contain  1 of  sulphate  of  calcium. 

Second  Analytical  Reaction. — Add  yellow  chromate  of 
potassium  (K^CrOJ  to  a calcium  solution  slightly  acidified 
with  acetic  acid  ; chromate  of  calcium  (CaCrOJ  is  pro- 
bably formed,  but  it  is  not  precipitated.  Barium  is  preci- 
pitated by  the  chromic  radical. 

These  two  negative  reactions  are  most  valuable  in  analysis,  as 
every  precipitant  of  calcium  is  also  a precipitant  of  barium  ; but  the 
above  two  reagents  are  precipitants  of  barium  only.  Hence  calcium, 
which  when  alone  can  be  readily  detected  by  the  following  reactions, 
cannot  by  any  reaction  be  detected  in  the  presence  of  barium.  But 
by  the  sulphuric  or  chromic  test  barium  is  easily  removed,  and  then 
either  of  the  following  reagents  will  throw  down  the  calcium. 

Other  Analytical  Reactions. — Add  carbonate  of  ammo- 
nium, phosphate  of  sodium,  arseniate  of  ammonium,  and 
oxalate  of  ammonium  to  calcium  solutions  as  described 
under  the  analj^tical  reactions  of  barium,  and  write  out 
descriptive  equations.  The  precipitates  correspond  in  ap- 
pearance to  those  of  barium  ; their  constitution  is  also 
identical,  hence  their  correct  formulae  can  easily  be  deduced. 
Of  these  precipitants  oxalate  of  ammonium  is  that  most 
commonly  used  as  a reagent  for  calcium  salts,  barium 
being  absent.  The  oxalate  of  calcium  is  insoluble  in  acetic, 

but  soluble  in  hydrochloric  or  nitric  acids. Calcium 

compounds  impart  a reddish  color  to  the  flame. 


QUESTIONS  AND  EXEECISES. 

143.  Enumerate  some  of  the  common  natural  compounds  of  cal- 
cium. 

144.  Explain,  by  an  equation,  the  action  of  hydrochloric  acid  on 
marble.  What  official  compounds  result  ? 

145.  Why  is  chloride  of  calcium  used  as  a desiccator  for  gases  ? 

146.  How  would  you  purify  Chloride  of  Calcium  which  has  been 
made  from  ferruginous  marble  ? Give  diagrams. 

147.  Write  a few  lines  on  the  chemistry  of  the  lime-kihi. 

148.  In  what  sense  is  the  conversion  of  chalk  into  lime  an  analy- 
tical action  ? 

149.  What  occurs  when  lime  is  slaked  ? 

150.  To  what  extent  is  lime  soluble  in  water  ? to  what  in  syrup  ? 

151.  Describe  the  preparation  of  the  official  Precipitated  Carbo- 
nate of  Calcium  ; in  what  does  it  differ  from  Prepared  Chalk  ? 


MAGNESIUM. 


99 


152.  In  wliat  does  filtering-paper  differ  from  other  kinds  of  paper  ? 

153.  Explain  the  construction  of  “ a washing  bottle’’  for  cleansing 
precipitates  by  water. 

154.  Define  decantation. 

155.  Describe  the  construction  and  manner  of  employment  of  a 
siphon. 

156.  Explain  the  mode  of  action  of  a siphon. 

157.  What  is  the  difference  between  Bone,  Bone-earth,  and  Pre- 
cipitated Phosphate  of  Calcium  ? 

158.  How  is  “ Bone-earth”  purified  for  use  in  medicine  ? 

159.  Explain  the  action  of  hydrochloric  acid  on  Animal  Charcoal 
in  the  conversion  of  Carbo  Animalis  into  Carho  Animalis  Purifi- 
catus. 

160.  What  is  the  chemical  difference  between  Carlo  Animalis 
and  Carbo  Ligni? 

161.  Give  equations  showing  the  conversion  of  Phosphate  of  Cal- 
cium into  Phosphate  of  Sodium. 

162.  Write  a short  article  on  the  manufacture,  composition,  and 
uses  of  bleaching-powder.” 

163.  How  may  calcium  be  detected  in  Gum-Arabic? 

164.  State  the  chemical  nature  of  Tragacanth. 

165.  To  w^hat  extent  is  sulphate  of  calcium  soluble  in  water  ? 

166.  Can  calcium  be  precipitated  from  an  aqueous  solution  con- 
taining barium  ? 

167.  Barium  being  absent,  what  reagents  may  be  used  for  the  de- 
tection of  calcium  ? Which  is  the  chief  test  ? 

MAGNESIUM. 

Symbol  Mg.  Atomic  weight  24. 

Source. — Magnesium  is  abundant  in  nature  in  the  form  of  magne- 
sian or  mountain  limestone,  or  dolomite,  a double  carbonate  of  mag- 
nesium and  calcium  in  common  use  as  a building-stone  [e.  g.  the 
Houses  of  Parliament,  and  the  School  of  Mines  in  London),  and 
magnesite,  a tolerably  pure  carbonate  of  magnesium,  though  too 
‘•stony”  for  direct  use  in  medicine,  even  if  very  finely  powdered. 
Chloride  of  magnesium  and  sulphate  of  magnesium  (Epsom  salt)  also 
occur  in  sea-water  and  the  water  of  many  springs.  Metallic  magne- 
sium may  be  obtained  from  the  chloride  by  the  action  of  sodium.  It 
burns  readily  in  the  air,  emitting  a dazzling  light  due  to  the  white 
heat  to  which  the  resulting  particles  of  magnesia  (MgO)  are  exposed. 
The  chloride  employed  as  a source  of  the  metal  is  obtained  by  dis- 
solving the  carbonate  in  hydrochloric  acid,  adding  some  chloride  of 
ammonium,  evaporating  to  dryness,  heating  the  residue  • in  a flask 
(on  the  small  scale  a large  test-tube  or  Florence  flask)  until  the  chlo- 
ride of  ammonium  is  all  volatilized  and  the  chloride  of  magnesium 
remains  as  a clear  fused  liquid.  The  latter  is  pouted  on  to  a clean 
earthenware  slab.  The  chloride  of  ammonium  prevents  reaction 
between  chloride  of  magnesium  and  water  in  the  last  stages  of  the 


100 


THE  METALLIC  RADICALS. 


operation  and  consequent  formation  of  oxide  (or  oxychloride)  of 
magnesium  and  hydrochloric  acid  gas. 

Quantivalence. — The  atom  of  magnesium  is  bivalent,  Mg". 

Reactions  having  Synthetical  Interest. 
Sulphate  of  Magnesium. 

First  Synthetical  Beaction. — To  a few  drops  of  sulphuric 
acid  and  a little  water  in  a test-tube  (or  to  larger  quanti- 
ties in  larger  vessels),  add  carbonate  of  magnesium  (pre- 
ferably the  native  carbonate  magnesite^  MgCO^)  until  effer- 
vescence ceases,  subsequently  boiling  to  aid  in  the  expul- 
sion of  the  carbonic  acid  gas.  The  filtered  liquid  is  a solu- 
tion of  sulphate  of  magnesium  (MgSOJ,  crystals  of  which, 
Epsom  salt  (MgSO^,  7H.^O)  {Magnesii  Sulphas^  U.  S.  P.), 
may  be  obtained  on  evaporating  most  of  the  water,  and  set- 
ting the  concentrated  solution  aside  to  cool.  This  is  an  ordi- 
nary manufacturing  process.  Instead  of  magnesite,  dolo- 
mite^ the  common  magnesian  limestone  (CaCO.^,  MgCOg) 
may  be  employed,  any  iron  being  removed  by  evaporating 
the  solution  (filtered  from  the  sulphate  of  calcium  produced) 
to  dryness,  gently  igniting  to  decompose  sulphate  of  iron, 
dissolving  in  water,  filtering  from  oxide  of  iron,  and  crys- 
tallizing. 

MgC03  + H,SO,  = MgSO,  + 11,0  + CO, 

Carbonate  of  Sulphuric  Sulphate  of  Water.  Carbonic 

magnesium.  acid.  magnesium.  acid  gas. 

Sulphate  of  magnesium  readily  crystallizes  in  large,  colorless, 
transparent,  rhombic  prisms ; but,  from  concentrated  solutions,  the 
crystals  are  deposited  in  short  thin  needles,  a form  more  convenient 
for  manipulation,  solution,  and  general  use  in  medicine. 

Iron  may  be  detected  in  sulphate  of  magnesium  by  adding  the 
common  alkaline  solution  of  chlorinated  lime  or  chlorinated  soda  to 
an  aqueous  solution  of  the  salt ; brown  hydrate  of  iron  (Fe26HO) 
being  precipitated.  Sulphydrate  of  ammonium  will  also  give  a black 
precipitate  if  iron  be  present. 

Carbonates  of  Magnesium. 

Second  Synthetical  Reaction. — To  solution  of  sulphate 
of  magnesium  add  solution  of  carbonate  of  sodium  and 
boil ; the  resulting  precipitate  is  light  carbonate  of  mag- 
nesium {Ma.gnesise  Carhoiias  Levis.^  B.  P.,  Magnesii  Car- 
honas.,  U.  S.  P.),  a white,  partly  amorphous,  partly  minutely 
crystalline  mixture  of  carbonate  and  h^^lrate  of  magnesium 
(SMgCO^,  Mg2IIO,  411^0).  A denser,  slightly  granular 


MAGNESIUM. 


101 


precipitate  of  similiar  chemical  composition  {Magnesiw  Gar- 
bo7ias,  B.  P.)  is  obtained  on  mixing  strong  solutions  of  the 
above  salts,  evaporating  to  dryness,  then  removing  the  sul- 
phate of  sodium  by  digesting  the  residue  in  hot  water,  filter- 
ing, washing,  and  drying  the  precipitate. 


4MgSO, 

Sulphate  of 
magnesium. 


+ 


+ 


4Na2C03 
Carbonate  of 
sodium. 

4Na,SO, 

Sulphate  of 
sodium. 


+ 


H,0  = 

Water. 


+ 


SMgCOg,  Mg2HO 

Official  carbonate  of 
magnesium. 

CO, 

Carbonic 
acid  gas. 


The  official  proportions  for  the  light  carbonate  are  10  of  sulphate . 
of  magnesium  and  12  of  crystals  of  carbonate  of  sodium,  each  dis- 
solved in  80  of  cold  water,  the  solutions  mixed,  boiled  for  15  minutes, 
the  precipitate  collected  on  a filter,  well  washed,  drained,  and  dried 
over  a water-bath.  The  heavier  carbonate  is  made  with  the  same 
proportions  of  salts,  each  dissolved  in  20  instead  of  80  of  water,  the 
mixture  evaporated  quite  to  dryness,  and  the  residue  washed  by 
decantation  or  filtration  until  all  sulphate  of  sodium  is  removed 
(shown  by  a white  precipitate — sulphate  of  barium — ceasing  to  form 
on  the  addition  of  solution  of  chloride  or  nitrate  of  barium  to  a little 
of  the  filtrate). 

Third  Synthetical  Reaction, — Pass  carbonic  acid  gas, 
generated  as  described  on  page  61,  into  a mixture  of  water 
and  carbonate  of  magnesium  contained  in  a test-tube. 
After  some  time,  separate  undissolved  carbonate  by  filtra- 
tion ; the  filtrate  contains  carbonate  of  magnesium  dissolved 
by  carbonic  acid.  When  of  a strength  of  about  13  grains 
in  one  ounce,  the  solution  constitutes  Fluid  Maynesia^^ 
{Liquor  Magne8iae  Garhonatis,^  B.  P.). 

Officially,  1 pint  is  directed  to  be  made  from  freshly  prepared  car- 
bonate. The  latter  is  obtained  by  adding  a hot  solution  gf  2 ounces 
of  sulphate  of  magnesium  in  half  a pint  of  water  to  one  of  2^  ounces 
of  crystals  of  carbonate  of  sodium  in  another  half  pint  of  water, 
boiling  the  mixture  for  a short  time  (to  complete  decomposition), 
filtering,  thoroughly  washing  the  precipitate,  placing  the  latter  in 
1 pint  of  distilled  water,  and  transmitting  carbonic  acid  gas  through 
the  liquid  (say,  at  the  rate  of  three  or  four  bubbles  per  second)  for 
an  hour  or  two,  then  leaving  the  solution  in  contact  with  the  gas 
under  slight  pressure  for  twenty-four  hours,  and,  finally,  filtering 
from  undissolved  carbonate,  and,  after  passing  in  a little  more  gas, 
keeping  in  a well-corked  bottle.  Slight  pressure  is  best  created  by 
placing  the  carbonate  and  water  in  a bottle  fitted  with  a cork  and 
tubes  as  for  a wash-bottle  (p.  81  or  93),  conveying  the  gas  by  a tube 
which  reaches  to  the  bottom,  and  allowing  excess  of  gas  to  flow  out 
by  the  upper  tube,  the  external  end  of  which  is  continued  to  the 
bottom  of  a common  phial  containing  about  an  inch  of  mercury. 

9* 


102 


THE  METALLIC  RADICALS. 


The  phial  should  be  loosely  plugged  with  cotton-wool,  to  prevent 
loss  of  metal  by  spurting  during  the  flow  of  the  gas  through  it. 
(Each  inch  in  depth  of  mercury  through  which  the  gas  escapes  corre- 
sponds to  about  half-a-pound  pressure  on  every  square  inch  of  surface 
within  the  apparatus.) 

Heat  a portion  of  the  solution  ; true  carbonate  of  magnesium  con- 
taining combined  water  (MgC03,3H20)  is  precipitated.  The  water 
in  this  compound  is  probably  in  the  state  of  water  of  crystallization, 
for  a salt  having  the  same  composition  is  deposited  in  crystals  by 
the  spontaneous  evaporation  of  the  solution  of  carbonate  of  mag- 
nesium. The  official  “ carbonate”  (3MgC03,Mg2H0,4H20)  is  another 
of  these  very  common  hydrous  compounds. 

Exposed  to  cold,  the  solution  of  “fluid  magnesia”  sometimes 
affords  large  thick  crystals  (MgC03,5H20),  which,  in  contact  with 
the  air,  lose  water,  become  opaque,  and  then  have  the  composition 
of  those  deposited  by  evaporation  (MgC03,3H20). 

Liquor  Magnesii  Citratis^  U.  S.  P.,  is  a solution  of  carbonate  of 
magnesium  and  bicarbonate  of  potassium  in  excess  of  citric  acid 
and  syrup  of  citric  acid. 

Oxide  of  Magnesium  (Magnesia). 

Fourth  Synthetical  Reaction, — Heat  light  dry  carbonate 
of  magnesium  in  a porcelain  crucible  over  a lamp  (or  in  a 
larger  earthen  crucible  in  a furnace)  till  it  ceases  to  effer- 
vesce on  adding,  to  a small  portion,  water  and  acid  ; the 
residue  is  light  magnesia  (MgO)  {Magnesia  Levis^  B.  P.). 
The  same  operation  on  the  heavy  carbonate  yields  heavy 
magnesia  (MgO)  {Magnesia,^  B.  P).  Both  are  sometimes 
spoken  of  as  calcined  magnesia^’  {Magnesia,^  U.  S.  P.)  A 
given  weight  of  the  official  light  magnesia  occupies  three 
and  a half  times  the  bulk  of  the  weight  of  heavy  magnesia. 

3MgC03,Mg2H0  = 4MgO  + H2O  + 3CO2 

Official  carbonate  of  Oxide  of  Water.  Carbonic 

magnesium.  magnesium.  acid  gas. 

A trace  only  of  magnesia  is  dissolved  by  pure  water. 
Moisten  a grain  or  two  of  magnesia  with  w^ater,  and  place 
the  paste  on  a piece  of  red  litmus-paper;  the  wet, spot,  after 
a time,  becomes  blue,  showing  that  the  magnesia  is  slightly 
soluble. 

Reactions  having  Analytical  Interest  (Tests). 

First  Analytical  Reaction. — Add  solution  of  hydrate  or 
carbonate  of  ammonium  to  a magnesian  solution  (sulphate 
for  example)  and  boil  the  mixture  in  a test-tube  ; the  pre- 
cipitation of  part  only  of  the  magnesium  as  113'drate 
(Mg2HO)  or  carbonate  (MgC03)  occurs.  Add  now  to  a 


MAGNESIUM. 


103 


small  portion  of  the  mixture  of  precipitate  and  liquid  a 
considerable  excess  of  solution  of  chloride  of  ammonium ; 
the  precipitate  is  dissolved. 

This  is  an  important  reaction,  especially  as  regards  carbonate  of 
magnesium,  the  presence  of  chloride  of  ammonium  enabling  the 
analyst  to  throw  out  from  a solution  barium  and  calcium  by  an  alka- 
line carbonate,  magnesium  being  retained.  The  cause  of  this  reac- 
tion is  the  tendency  of  magnesium  to  form  soluble  double  salts  with 
potassium,  sodium,  or  ammonium.  In  analysis,  the  chloride  of  am- 
monium should  be  added  before  the  carbonate,  as  it  is  easier  to  pre- 
vent precipitation  than  to  redissolve  a precipitate  once  formed. 

Second  Analytical  Reaction. — To  some  of  the  solution 
resulting  from  the  last  reaction,  add  solution  of  phosphate 
of  sodium  or  ammonium;  phosphate  of  magnesium  and 

ammonium  (MgNH^POJ  is  precipitated. 36?.  To  another 

portion  add  arseniate  of  ammonium ; arseniate  of  magne- 
sium and  ammonium  (MgNH^AsO^)  is  precipitated. 

Note. — Barium  and  calcium  are  also  precipitated  by  alkaline  phos- 
phates and  arseniates.  The  other  precipitants  of  magnesium  are 
also  precipitants  of  barium  and  calcium.  In  other  words,  there  is 
no  direct  test  for  magnesium.  Hence  the  analyst  always  removes 
any  barium  or  calcium  by  an  alkaline  carbonate,  as  above  indicated ; 
the  phosphate  of  sodium  or  arseniate,  or  phosphate  of  ammonium, 
then  become  very  delicate  tests  of  the  presence  of  magnesium.  In 
speaking  of  magnesium  tests,  the  absence  of  barium  and  calcium 
salts  is  to  be  understood. 


QUESTIONS  AND  EXEKCISES. 

168.  Name  the  natural  sources  of  the  various  salts  of  magnesium. 

169.  Give  a process  for  the  preparation  of  Epsom  salt. 

170.  Draw  diagrams  illustrative  of  the  formation  of  sulphate  of 
magnesium  from  magnesite  and  from  dolomite. 

171.  Show  by  an  equation  the  process  for  the  preparation  of  the 
official  Carbonate  of  Magnesium. 

172.  What  circumstances  determine  the  two  different  states  of 
aggregation  of  the  Magnesice  Carbonas  and  Magnesice  Carhonas 
Levis  ? 

173.  What  are  the  relations  of  Magnesia  dvadi  Magnesia  Levis  to 
the  official  Carbonates  of  Magnesium  ? 

174.  How  much  denser  is  the  one  than  the  other? 

175.  Is  magnesia  soluble  in  water? 

176.  How  is  “Fluid  Magnesia”  prepared? 

177.  Mention  the  effects  of  heat  and  cold  on  “Fluid  Magnesia.” 

178.  How  much  magnesia  (MgO)  can  be  obtained  from  100  grains 
of  Epsom  Salt  ? 


104 


THE  METALLIC  RADICALS. 


179.  Calculate  the  amount  of  official  Carbonate  of  Magnesium 
which  will  yield  100  grains  of  magnesia. 

180.  Can  magnesium  be  detected  in  presence  of  barium  and  cal- 
cium? 

181.  Describe  the  analysis  of  an  aqueous  liquid  containing  salts  of 
barium,  calcium,  and  magnesium. 

182.  How  may  magnesium  be  precipitated  from  solutions  con- 
taining ammoniacal  salts  ? 

Quantivalence. 

On  reviewing  the  foregoing  statements  regarding  compounds  of 
the  three  univalent  radicals,  potassium,  sodium,  and  ammonium,  and 
the  three  bivalent  elements,  barium,  calcium,  and  magnesium,  the 
doctrine  of  quantivalence  will  be  more  clearly  understood,  and  its 
usefulness  more  apparent.  Quantivalence,  or  the  value  of  atoms,  is, 
in  short,  in  chemistry,  closely  allied  to  value  in  commercial  barter. 
A number  of  articles,  differing  much  in  weight,  appearance,  and 
general  characters,  may  be  of  equal  money  value ; and  if  these  be 
regarded,  for  convenience,  as  having  a sort  of  unit  of  value,  others 
worth  double  as  much  might  be  termed  bivalent,  three  times  as 
much  trivalent,  and  so  on.  In  like  manner,  chemical  radicals,  no 
matter  whether  elementary,  like  potassium  (K),  iodine  (I),  or  sul- 
phur (S),  or  compound,  like  those  of  nitrates  (NOg),  sulphates  (SO^), 
or  acetates  (C2H3O.J,  have  a given  chemical  value  in  relation  to  each 
other,  and  are  exchangeable  for,  and  will  unite  with  each  other  to 
an  extent  determined  by  that  value. 

Most  chemical  salts  apparently,  though  probably  not  really,  have 
two  parts,  a basylous  and  an  acidulous,  the  one  quantivalently  bal- 
ancing the  other.  The  formulae  of  the  chief  of  these  radicals  and 
their  quantivalence  are  given  below.  Examples  of  formulae  of  salts 
containing  univalent,  bivalent,  and  trivalent  radicals  are  also  ap- 
pended. 


Quantivalence  of  Common  Radicals. 


Univalent  Radicals, 
or  Monads. 

Bivalent  Radicals, 
or  Dyads. 

Trivalent  Radicals, 
or  Triads. 

Acidulous. 

Basylous 

Acidulous. 

Basylous. 

Acidulous. 

Basylous. 

H 

H 

0 

Ca 

PO* 

As 

Cl 

K 

so* 

Mg 

BO, 

Sb 

I 

Na 

CO, 

Zu 

CA5O, 

Bi 

HO 

NH, 

cA 

Cu 

AsO, 

f Fe“*(ic) 

NOg 

c*n*o, 

Hg(ic) 

AsO* 

J or 

c,ri,o, 

Hg(ous) 

s 

Fe(ous) 

0*1130, 

1 Fe''‘,(ic) 

Note. — The  hydrogen  (II)  in  the  basylous  parts  of  salts  has  en- 
tirely different  functions  to  the  hydrogen  (H)  in  the  acidulous  part. 


QUANT I VALENCE. 


105 


The  latter  gives  compounds  commonly  termed  hydrides  (e,  g.  CuH^) ; 
ill  the  former  the  element  is  the  basylous  radical  of  acids  (e.  g.  HCl, 
H.^SO^).  In  compound  radicals,  e.  g.  O2H3O2  or  NH^,  the  proper- 
ties of  hydrogen  are  no  longer  apparent : the  chemical  force  resident 
with  the  atoms  of  such  radicals  seems  to  be  mainly  exerted  in  binding 
those  atoms  together. 


Examples  of  Formulae  containing  Univalent,  Bivalent,  and  Tri valent 
Radicals. 

The  reader  will  find  instructive  practice  in  writing  twenty  or 
thirfy  imaginary  formulae  of  salts  by  placing  in  juxtaposition 
acidulous  and  basylous  radicals,  as  in  the  following  examples. 
Just  as  in  a pair  of  scales  a 2-lb.  weight  must  be  balanced  by 
two  1-lb.  weights,  or  a 4-lb.  weight  by  two  2-lb.  weights,  or  by  one 
3-lb.  and  one  1-lb.  weight,  so  a bivalent  radical  unites  with  a bi- 
valent radical  or  with  two  univalent  radicals,  a quadrivalent  radical 
with  two  bivalent  radicals,  or  with  one  trivalent  and  one  univalent 
radical,  and  so  on. 

(R  = any  basylous  Radical.)  {R  = any  acidulous  Radical.) 


General  formula, 

WR'  

WR\ 

W"R'^ 

R\R''  I 

U'U'R" I 

K,R'"  . . . . ) 

W,R'R'"  ....  I 

R"R" 



R"R'R'" 

R'"R"R 

R"',R'\R" 

R"\R", 

R'"R'" 



Rtn  Tit/ 




Examples. 

KI,  NaCl,  AgN03. 

CaCl^,  Zn2C2H302,  Pb2N03(BaN03C2H302). 
Bi3N03,  ASH3,  SbCl3. 

K,C03,  Na^SO,,  II^C.H.O,. 

KilC03,  NaHSO^,  KHO^H^O^. 

Am3PO„  K3C6H5O7,  H3ASO3. 

Na^HPO,,  Na.HAsO,. 

CaC03,Mg0,  CuSO„  HgO,  FeSO^. 

Ca32P04,  Oa32C,H50,. 

MgAmPO,,  CUHASO3. 

BiONO,. 

Bi202C03. 

AS2O3,  Sb203. 

BiO.H^O^. 

Fe2Cl6,  Fe26N03,  Fe26C2H302. 

Fe203,  Fe23SO,. 


Quadrivalent  Radicals  or  Tetrads,  Quinquivalent  Radicals  or  Pen- 
tads, and  Sexivalent  Radicals  or  Hexads,  are  known. 


EXERCISE. 

183.  Write  an  exposition  of  the  doctrine  of  Qnantiva- 
lence  within  the  limits  of  a sheet  of  note  paper. 


106 


THE  METALLIC  RADICALS. 


DIRECTIONS  FOR  APPLYING  THE  FOREGOING  ANALYTICAL  RE- 
ACTIONS TO  THE  ANALYSIS  OF  AN  AQUEOUS  SOLUTION  OF 
A SALT  OF  ONE  OF  THE  METALS,  BaRIUM,  CaLCIUM,  MAG- 
NESIUM. 

Add  yellow  chromate  of  potassium  to  a portion  of  the 
solution  to  be  examined;  a precipitate  indicates  barium. 

If  no  barium  is  present,  add  chloride  and  carbonate  of 
ammonium,  and  boil;  a precipitate  indicates  calcium. 

If  barium  and  calcium  are  proved  to  be  absent,  add  chlo- 
ride of  ammonium,  ammonia,  and  then  either  phosphate  of 
sodium  or  arseniate  of  ammonium  ; a white  granular  pre- 
cipitate indicates  magnesium. 

Ammonia  is  here  added  to  yield  the  necessary  elements  to  ammo- 
nio-magnesian  phosphate  or  ammonio-magnesian  arseniate,  both  of 
which  are  highly  characteristic  precipitates ; and  chloride  of  ammo- 
nium is  added  to  prevent  a mere  partial  precipitate  of  the  magnesium 
by  the  ammonia. 


DIRECTIONS  FOR  APPLYING  THE  FOREGOING  ANALYTICAL  RE- 
ACTIONS TO  THE  ANALYSIS  OF  AN  AQUEOUS  SOLUTION  OF 

ONE,  TWO.  OK  Aljli  THREE  OF  THE  METALS,  BaRIUM, 

Calcium,  Magnesium. 

Add  chromate  of  potassium  to  the  solution  ; barium,  if 
present,  is  precipitated.  Filter,  if  necessary,  and  add  to 
the  filtrate  (that  is,  the  liquid  which  has  run  through  the 
filter)  chloride,  hydrate,  and  carbonate  of  ammonium,  and 
boil;  calcium,  if  present,  is  precipitated.  Filter,  if  requi- 
site, and  add  phosphate  of  sodium  ; magnesium,  if  present, 
is  precipitated. 

Note. — Eed  chromate  of  potassium  must  not  be  used  in  these  ope- 
rations, or  a portion  of  the  barium  will  remain  in  the  liquid  and  be 
thrown  down  with,  or  in  place  of,  the  carbonate  of  calcium  {vide 
p.  88).  The  yellow  chromate  must  not  contain  carbonate  of  potas- 
sium, or  calcium  will  be  precipitated  with,  or  in  place  of,  barium. 
The  absence  of  carbonate  is  proved  by  the  non-occurrence  of  effer- 
vescence on  the  addition  of  hydrochloric  acid  to  a little  of  the  solu- 
tion of  the  chromate,  previously  made  hot  in  a test-tube.  If  the 
yellow  chromate  has  been  prepared  by  adding  excess  of  ammonia  to 
solution  of  red  chromate  of  potassium,  its  addition  to  the  liquid  to 
be  analyzed  must  be  preceded  by  that  of  solution  of  chloride  of  am- 
monium ; the  precipitation  of  a portion  of  the  magnesium  (by  the 
free  ammonia  in  the  yellow  chromate)  is  thus  prevented,  for  chloride 
of  ammonium  solution  is  a good  solvent  of  hydrate  (and  carbonate) 
of  magnesium. 


BARIUM,  CALCIUM,  MAGNESIUM. 


lOT 


TABLE  OF  SHORT  DIRECTIONS  FOR  APPLYING  THE  FOREGOIN-G 
ANALYTICAL  REACTIONS  TO  THE  ANALYSIS  OF  AN  AQUEOUS 
SOLUTION  OF  SALTS  CONTAINING  ATsTY  OK  ALL  OF  THE  ME- 
TALLIC ELEMENTS  HITHERTO  CONSIDERED. 


To  the  solution  add  AmCl,  AmHO,  Am^COg;  boil  and  filter. 


Precipitate 

Ba  Oa. 

Wash,  dissolve  in  HC2H3O2, 
add  K2Cr04,  and  filter. 

Filtrate 

Mg  Am  Na  K. 

Add  Am2HP04,  shake,  filter. 

Precipitate 

Filtrate 

Precipitate 

Filtrate 

Ba 

Ca. 

Test  by 
AiBjO.O^. 

Mg. 

Am  Na  K. 

Evap.  to  dryness,  ignite, 
dissolve  residue  in 
water. 

Test  for  K by  Pt  Cl^. 
Test  for  Na  by  fiame. 
Test  orig.  sol.  for  Am. 

Note  1. — The  analysis  of  solutions  containing  the  foregoing  metals 
is  commenced  by  the  addition  of  chloride  of  ammonium  (AmCl)  and 
ammonia  (AmHO),  simply  as  a precautionary  measure,  the  former 
compound  preventing  partial  precipitation  of  magnesium,  the  latter 
neutralizing  acids.  The  carbonate  of  ammonium  (Am.^COg)  is  the 
important  group-reagent — the  precipitant  of  barium  and  calcium. 

Note  2. — In  the  above,  and  in  subsequent  charts  of  analytical 
processes,  the  leading  precipitants  will  be  found  to  be  ammonium 
salts.  These,  being  volatile,  can  be  got  rid  of  towards  the  end  of  the 
operations,  and  thus  the  detection  of  potassium  and  sodium  be  in  no 
way  prevented — an  advantage  which  could  not  be  had  if  such  salts 
as  chromate  of  potassium  or  phosphate  of  sodium  were  the  group- 
precipitants  employed. 

Note  3. — Acetic,  and  not  hydrochloric  or  Iiitric,  acid  is  used  in 
dissolving  the  barium  and  calcium  carbonates,  because  chromate  of 
barium,  on  the  precipitation  of  which  the  detection  of  barium  de- 
pends, is  soluble  in  the  stronger  acids,  and  therefore  could  not  be 
thrown  down  in  their  presence. 

Note  on  Classification. — The  compounds  of  barium,  calcium,  and 
magnesium,  like  those  of  the  alkali  metals,  have  many  analogies ; 
the  carbonates,  phosphates,  and  arseniates  of  each  are  insoluble, 
which  sufficiently  distinguishes  them  from  the  members  of  the  class 
first  studied.  They  possess,  moreover,  well-marked  differences,  so 
that  their  separation  from  each  other  is  easy.  The  solubility  of  their 
hydrates  in  water  marks  their  connection  with  the  alkali  metals ; the 
slightness  of  that  solubility,  diminishing  as  we  advance  further  and 
further  from  the  alkalies,  baryta  being  most  and  magnesia  least 


108 


THE  METALLIC  RADICALS. 


soluble  in  water,  points  to  their  connection  with  the  next  class  of 
metals,  the  hydrates  of  which  are  insoluble  in  water.  These  con- 
siderations must  not,  however,  be  over-valued.  Though  the  solu- 
bility of  their  hydrates  places  barium  nearest  and  magnesium  furthest 
from  the  alkali  metals,  the  solubility  of  their  sulphates  gives  them 
the  opposite  order,  magnesium-sulphate  being  most  soluble,  calcium- 
sulphate  next,  strontium-sulphate  third  (strontium  is  a rarer  element, 
which  will  be  mentioned  subsequently),  and  barium  sulphate  insoluble 
in  water.  These  elements  are  sometimes  spoken  of  as  the  metals  of 
the  alkaline  earths. 

Note. — In  connection  with  the  bivalence  of  the  metals  Barium, 
Calcium,  and  Magnesium,  it  is  interesting  to  note  that  just  as  biva- 
lent acidulous  radicals  give  salts  containing  two  atoms  of  univalent 
basylous  radicals  (K.^SO^,  NaHSO^,  H2CO3,  KNaC4H^03),  so  biva- 
lent basylous  radicals  yield  salts  containing  tw^o  atoms  of  univalent 
acidulous  radicals,  as  seen  in  acetonitrate  of  barium,  BaC2H302^"^3» 
a salt  w^hich  is  a definite  compound,  and  not  a mere  mixture  of  ace- 
tate wfith  nitrate  of  barium.  A very  large  number  of  such  salts  is 
known. 


Distillation. 

The  water  with  w^hich,  in  analysis,  solution  of  a salt  or  dilution  of 
a liquid  is  effected  should  be  pure.  Well  or  river-w^ater  [Aqua,  U. 
S.  P.)  is  unfit  for  the  purpose,  because  containing  alkaline  and 
earthy  salts  (about  20  to  60  grains  per  gallon),  derived  from  the 
soil  through  w^hich  the  water  percolates,  and  rain-w^ater  is  not  unfre- 
quently  contaminated  wuth  the  dust  and  debris  which  fall  on  the 
roofs  whence  it  is  usually  collected.  Such  w^ater  is  purified  by  dis- 
tillation, an  operation  in  which  the  w^ater  is  by  ebullition  converted 
into  steam,  and  the  steam  condensed  again  to  w'ater  in  a separate 
vessel,  the  fixed  earthy  and  other  salts  remaining  in  the  vessel  in 
w^hich  the  wmter  is  boiled.  On  the  large  scale,  ebullition  is  effected 
in  metal  boilers  having  a hood  or  head  in  which  is  a lateral  opening 
through  which  passes  the  steam  ; on  the  small  scale,  either  a common 
glass  flask  is  employed,  into  the  neck  of  which,  by  a cork,  is  inserted 
a glass  tube  bent  to  an  acute  angle,  or  a retort  is  used,  a sort, of 
long-necked  Florence  flask,  dextrously  bent  near  the  body  by  the 
glass-w'orker  to  an  appropriate  angle  (hence  the  name  retort,  from 
retorqueo,  to  bend  back).  Condensation  is  effected  by  surrounding 
the  lateral  steam-tube  wuth  cold  water.  In  large  stills  the  steam- 
tube,  or  condensing-iuorm,  is  usually  a metal  (tin)  pipe,  twisted  into 
a spiral  form  for  the  sake  of  compactness,  and  so  fixed  in  a tub  that 
a few'  inches  of  one  end  of  the  pipe  may  pass  through  and  closely  fit 
a hole  bored  near  the  bottom  of  the  tub.  Cold  w'ater  is  kept  in 
contact  w'ith  the  exterior  of  the  pipe,  provision  being  made  for  a 
continuous  supply  to  the  bottom,  wdiile  the  w'ater  heated  by  the  con- 
densing steams  runs  off  fromThe  top  of  the  column.  The  condenser 
for  a flask  or  retort  may  be  a simple  glass  tube  of  any  size,  placed 
within  a second  much  w ider  tube  (a  common  long,  narrow'  lami>glass 
answers  very  w’ell  for  experimental  operations),  the  tube  being  con- 
nected at  the  extremities  of  the  w'ider  by  bored  corks ; a stream  of 


ZINC. 


109 


water  passes  into  one  end  of  the  inclosed  space  (the  end  furthest 
from  the  retort),  through  a small  glass  tube  inserted  in  the  cork,  and 
out  at  the  other  through  a similar  tube.  The  common  (Liebig’s) 
form  of  laboratory  condenser  is  a glass  tube  three-fourths  of  an  inch 
wide  and  a yard  long,  surrounded  by  a shorter  tin  or  zinc  tube  two 
inches  in  diameter,  and  having  at  each  extremity  a neck,  through 
which  the  glass  tube  passes.  The  ends  of  the  necks  of  the  tin  tube, 
and  small  portions  of  the  glass  tube  near  them,  are  connected  by 
means  of  a strip  of  sheet  caoutchouc  carefully  bound  round.  An 
aperture  near  the  lower  part  of  the  tin  tube  provides  for  the  admis- 
sion of  a current  of  cold  water,  and  a similar  aperture  near  the  top 
allows  the  escape  of  heated  water.  The  inner  tube  may  thus  con- 
stantly be  surrounded  by  cold  water,  and  heated  vapors  passing 
through  it  be  perfectly  cooled  and  condensed. 

In  distilling  several  gallons  of  water  for  analytical  or  medicinal 
purposes  [Aqua  Destillata,  B.  P.  and  U.  S.  P.),  the  first  two  or  three 
pints  should  be  rejected,  because  likely  to  contain  ammoniacal  and 
other  volatile  impurities. 

Rectification  is  the  process  of  redistilling  a distilled  liquid.  Rec 
tified  s'pirit  is  spirit  of  wine  thus  treated. 

Dry  or  destructive  distillation  is  distillation  in  which  the  con- 
densed products  are  directly  formed  by  the  decomposing  infiuence  of 
the  heat  applied  to  the  dry  or  non-volatile  substances  in  the  retort 
or  still. 


EXEKCISE. 

184.  Write  from  memory  two  or  three  paragraphs  descriptive  of 
distillation. 


ZINC.  ALUMINIUM,  IRON. 

These  three  elements  are  classed  together  for  analytical  conven 
ience  rather  than  for  more  general  analogies. 

ZINC. 

Symbol  Zn.  Atomic  weight  65. 

Source. — Zinc  is  tolerably  abundant  in  nature  as  sulphide  (ZnS) 
or  blende,  and  carbonate  (ZnCOg)  or  calamine  (from  calamus,  a 
reed,  in  allusion  to  the  appearance  of  the  mineral).  The  ores  are 
roasted  to  expel  sulphur,  carbonic  acid  gas,  and  some  impurities,  and 
the  resulting  oxide  distilled  with  charcoal,  when  the  metal  vaporizes 
and  readily  condenses.  Zinc  is  a brittle  metal,  but  at  a temperature 
somewhat  below  300^  F.  is  malleablOj  and  may  be  rolled  into  thin 
sheets.  Above  400^  it  is  again  brittle,  and  may  then  be  pulverized. 
At  773^  F.  it  melts,  and  at  a bright  red  heat  is  volatile. 

Uses. — Its  use  as  a metal  is  familiar ; alloyed  with  nickel  it  yields 
german  silver ; with  twice  its  weight  of  copper  forms  common  brass, 
and  as  a coating  on  iron  (the  so-called  galvanized  iron)  greatly 
10 


110 


THE  METALLIC  RADICALS. 


retards  the  formation  of  rust.  Most  of  the  salts  of  zinc  are  pre- 
pared, directly  or  indirectly,  from  the  metal  (Zinciim,  B.  P.  and 

U.  S.  P.).^ 

Quantivalence. — The  atom  of  zinc  is  bivalent,  Zn". 

Molecular  Weight, — Some  remarks  on  this  point  will  be  made 
under  Mercury. 


Reactions  having  (a)  Sythetical  and  {h)  Analytical 
Interest. 

(a)  Synthetical  Reactions. 

Sulphate  of  Zinc, 

Fir^t  Synthetical  Reaction. — Heat  zinc  (4  pts.)  with  water 
(20  pts.)  and  sulphuric  acid  (3  11.  pts.)  in  a test-tube  (or 
larger  vessel)  until  gas  ceases  to  be  evolved ; solution  of 
sulphate  of  zinc  (ZnSOJ  results.  Filter  and  concentrate 
the  solution  in  an  evaporating  dish ; on  cooling,  color- 
less, transparent,  prismatic  crystals  of  Sulphate  of  Zinc 
(ZnS04,'lH20)  are  deposited  {Zinci  Sulphas^  B.  P.  and 
U.  S.  P.). 

Zn^  + 2H2SO,  + xUfi  = 2ZnSO,  -f  + 2H2 

Zinc.  Sulphuric  Water.  Sulphate  of  Water.  Hydrogen, 

acid.  Zinc. 

Zinc  does  not  displace  hydrogen  from  the  sulphuric  acid  alone,  nor 
from  the  water  alone,  yet  the  mixture  affords  hydrogen.  The  pro- 
bable explanation  is  that  as  sulphuric  acid  combines  wuth  several 
different  quantities  of  w^ater  to  form  definite  hydrous  compounds 
(H2SO4,  H2O  ; H2SO4,  2H2O  ; etc),  it  is  one  of  these  that  is  decom- 
posed with  elimination  of  hydrogen.  At  present  we  can  only  say 
that  an  unknowm  (cc)  amount  of  w^ater  is  required  in  the  reaction. 

Note. — This  reaction  affords  hydrogen  and  sulphate  of  zinc ; it 
also  gives  electricity.  Of  several  methods  of  evolving  hydrogen,  it 
is  the  most  convenient;  of  the  two  or  three  means  of  preparing 
sulphate  of  zinc  it  is  that  most  commonly  employed;  and  of  the 
many  reactions  which  may  be  utilized  in  the  development  of  dynamic 
electricity  it  is  at  present  the  cheapest  and  most  manageable.  The 
apparatus  in  which  the  reaction  is  effected  differs  according  to  the 
requirements  of  the  operator;  if  the  sulphate  of  zinc  alone  is  wanted, 
an  open  dish  is  all  that  is  necessary,  the  action  being,  perhaps, 
accelerated  by  heat;  if  hydrogen,  a closed  vessel  and  delivery-tube; 
if  electricity,  square  vessels  called  cells  and  certain  complementary 
materials,  forming  altogether  what  is  termed  a battery.  In  each 
operation  for  one  product  the  other  two  are  commonly  wasted.  It 
would  not  be  difficult  for  the  operator,  as  a matter  of  amusement,  to 
construct  an  apparatus  in  which  all  three  products  should  be  collected. 

Purification. — Impure  sulphate  of  zinc  may  be  purified  in  the 
same  manner  as  impure  chloride  (see  next  reaction). 


ZINC. 


Ill 


Sulphate  of  zinc  is  isomorphous  with  sulphate  of  magnesium,  and, 
like  that  salt,  loses  six-sevenths  of  its  water  of  crystallization  at 
2120  F. 


Chloride  of  Zinc. 

Second  Synthetical  Reaction, — Dissolve  zinc  in  hydro- 
chloric acid  mixed  with  half  its  bulk  of  water ; the  resulting 
solution  contains  chloride  of  zinc.  Evaporate  the  liquid 
till  no  more  steam  escapes ; Chloride  of  Zinc  (ZnCl2)  in  a* 
state  of  fusion  remains,  and,  on  cooling,  is  obtained  as  a 
white  opaque  solid  {Zinci  Ghloridum,,  B.  P.  and  U.  S.  P.). 
It  is  soluble  in  water,  alcohol,  or  ether. 

Zn^  -f  4Hei  2ZnCl3  + 2H, 

Zinc.  Hydrochloric  Choloride  Hydrogen, 

acid.  of  zinc. 

This  reaction  is  analogous  to  that  previously  described.  The 
Burnett  deodorizing  or  disinfecting  liquid  is  solution  of  chloride  of 
zinc. 

Purification  of  Chloride  or  Sulphate  of  Zinc. — Zinc  sometimes 
contains  traces  of  iron  or  lead ; and  these,  like  zinc,  are  dissolved  by 
most  acids,  with  formation  of  soluble  salts ; they  may  be  recognized 
in  the  liquids  by  applying  the  tests  described  hereafter  to  a little  of 
the  solution  in  a test-tube  (p.  114).  Should  either  be  present  in  the 
above  solution,  a little  chlorine  water  is  added  to  the  liquid  till  the 
odor  of  chlorine  is  permanent,  and  then  the  whole  well  shaken  with 
some  hydrate  of  zinc  or  the  common  official  “carbonate”  of  zinc 
(really  hydra to-carbonate — see  next  page).  In  this  way  iron  is  pre- 
cipitated as  ferric  hydrate,  and  lead  as  peroxide  : — 

*2FeCl2  4-  CI2  = ^Fe^Cl^ 

Ferrous  chloride.  Chlorine.  Ferric  chloride. 

+ 3ZnC03  -f  SH^O  = Fe.fiUO  + SZnCl^  + 300., 

Ferric  Carbonate  Water.  Ferric  hydrate.  Chloride  Carbonic 

chloride.  of  zinc.  of  zinc.  acid  gas. 

PbOL,  4-  CI2  4-  2ZnC03  = PbO^  4-  2ZnCl2  4-  200., 

Chloride  Chlorine.  Carbonate  Peroxide  Chloride  Carbonic 

of  lead.  of  zinc.  of  lead.  of  zinc.  acid  gas. 

In  the  British  Pharmacopoeia  the  presence  of  impurities  in  the 
zinc  is  assumed,  and  the  process  of  purification  just  described  incor- 
porated with  the  process  of  preparation  of  Zinci  Ghloridum,  Liquor 
Zinci  Chloridi,  and  Zinci  Sulphas.  In  the  purification  of  the  sul- 
phate of  zinc,  the  action  of  chlorine  on  any  ferrous  sulphate  will 
result  in  the  formation  of  ferric  sulphate  as  well  as  ferric  chloride  : — 

6FeS0,  4-  Cle  = 2(Fe23SOJ  4-  Fe^Clg; 

* It  will  be  noticed  that  the  iron  is  represented,  in  these  equations, 
as  exerting  both  bivalent  and  trivalent  activity  ; this  will  be  alluded 
to  when  iron  comes  under  consideration. 


112 


THE  METALLIC  RADICALS. 


carbonate  of  zinc  will  then  give  chloride  as  well  as  sulphate  of  zinc, 
and  thus  the  whole  quantity  of  sulphate  of  zinc  be  slightly  contami- 
nated by  chloride.  On  evaporating  and  crystallizing,  however,  the 
chloride  of  zinc  will  be  retained  in  the  mother-liquor. 

For  Liquor  Zinci  Chloridi,  B.  P.,  1 pound  of  zinc  is  placed  in  a 
mixture  of  44  fluidounces  of  hydrochloric  acid  and  20  of  water,  the 
mixture  ultimately  warmed  until  no  more  gas  escapes,  filtered  into  a 
bottle,  chlorine  water  added  until  the  liquid  after  shaking  smells 
fairly  of  chlorine,  about  half  an  ounce  or  somewhat  more  of  carbonate 
of  zinc  shaken  up  with  the  solution  until  a brown  precipitate  (of 
ferric  hydrate  or  peroxide  of  lead,  or  both)  appears,  the  whole  filtered 
and  the  filtrate  evaporated  to  40  fluidounces.  One  fluidounce  con- 
tains 366  grains  of  chloride  of  zinc.  If  there  is  reason  to  believe  that 
neither  iron  nor  lead  is  present  in  the  zinc,  the  treatment  of  chlorine, 
water,  and  carbonate  of  zinc  may  be  omitted.  The  Liquor  Zinci 
Chloridi^  U.  S.  P.,  is  prepared  by  a somewhat  similar  process,  nitric 
acid,  however,  is  used  instead  of  chlorine  water ; the  solution  con- 
tains 375  grains  of  chloride  of  zinc  in  one  fluidounce. 

Carbonate  of  Zinc. 

Third  Synthetical  Beaction. — To  solution  of  any  given 
quantity  of  sulphate  of  zinc  in  twice  its  weight  of  water 
(in  a test-tube,  evaporating  basin,  or  other  large  or  small 
vessel),  add  about  an  equal  quantity  of  carbonate  of  so- 
dium, also  dissolved  in  twice  its  weight  of  water,  and  boil; 
the  resulting  white  precipitate  is  so-called  Carbonate  of 
Zinc  {Zinci  Carhonas^  B.  P.,  Zinci  Carhonas  Precipitata^ 
U,  S.  P.),  a mixture  of  carbonate  (ZnCO^)  and  h3^drate 
(Zn2HO),  in  the  proportion  of  one  molecule  of  the  former 
and  two  of  the  latter,  together  with  a molecule  of  water 
(HgO).  It  maybe  washed,  drained,  and  dried  in  the  usual 
manner.  It  is  used  in  the  arts  under  the  name  of  zinc- 
white^  and  frequently  in  medicine  in  the  form  of  ointment 
( Geratum  Zinci  Carhonatis^  U.  S.  P.). 

3ZnSO,  + 2H,0  + 3^XC03  = ZnC03,2ZnII.,0,  -f-  2CO., 

Sulphate  Water.  Carbonate  Official  carbonate  Carbonic 

of  zinc.  of  .sodium.  of  zinc.  acid  gas. 

+ 3Na.,SO, 

Sulphate 
of  sodium. 

Acetate  of  Zinc. 

Fourth  Syjithetical  Beaction, — Collect  in  a filter  the  pre- 
cipitate obtained  in  the  last  reaction,  wash  with  distilled 
water,  and  dissolve  a portion  in  strong  acetic  acid;  the 
resulting  solution  contains  acetate  of  zinc  (Zn2C.^H30.^), 
and,  on  evaporating,  and  setting  aside  for  a day,  3uelds 


ZINC. 


113 


lamellar  pearly  crystals  (Zn2C2H30^,2H^0).  This  is  the 
process  for  Zinci  Acetas,  B.  P. 

ZnC03,2ZnH202  + 6HC2H3O2  = 3(Zn2C2H302)  + 5H,0 

Official  carbonate  Acetic  Acetate  of  zinc.  Water, 

of  zinc.  acid. 

+ CO, 

Carbonic 
acid  gas. 

The  U.  S.  P.  process  consists  in  digesting  oxide  of  zinc 
in  acetic  acid,  heating  the  mixture  to  boiling  point,  filter- 
ing while  hot,  and  setting  aside  the  clear  solution  to  crys- 
tallize. 


Oxide  of  Zinc. 

Fifth  Synthetical  Reaction. — Dry  the  remainder  of  the 
precipitated  carbonate  (bj^  placing  the  open  filter  on  a 
plate  over  a dish  of  water  kept  boiling),  and  then  heat  it 
in  a small  crucible  till  it  ceases  to  effervesce  on  the  addi- 
tion of  water  and  acid  to  trial  samples  taken  out  of  the 
crucible  from  time  to  time;  the  product  is  Oxide  of  Zinc 
{Zinci  Oxidum.,1^.  P.  and  U.  S.  P.),  much  used  in  the  form 
of  ointment  ( Unguentum  Zinci^  B.  P.,and  Unguentum  Zinci 
Oxidi,  U.  S.  P.). 

ZnC03,  2ZnH202  = 3ZnO  + + CO^ 

Official  carbonate  Oxide  of  Water.  Carbonic 

of  zinc.  zinc.  acid  gas. 

Note. — This  oxide  is  yellow  while  hot,  and  of  a very  pale  yellow 
or  slight  buff  tint  when  cold,  not  actually  white  like  the  oxide  pre- 
pared by  the  combustion  of  zinc  in  air.  The  latter  variety  occurs  in 
commerce  under  the  name  of  Hubbuck’s  oxide  of  zinc.  Its  prepara- 
tion can  only  be  practically  accomplished  on  the  large  scale,  but  the 
chief  features  of  the  action  may  be  observed  by  heating  a piece  of 
zinc  in  a small  porcelain  crucible  till  it  burns ; flocks  escape  from 
the  crucible,  float  about  in  the  air,  and  slowly  fall.  These  are  the 
old  Flores  Zinci,  Lana  Fhilosophica,  or  Nihilum  Album, 

Valerianate  of  Zinc. 

Sixth  Synthetical  Reaction. — Valerianate  of  Zinc  (Zn2C5 
H9O2)  {Zinci  Valerianas,,  B.  P.)  is  prepared  by  mixing 
strong  solutions  of  sulphate  of  zinc  and  valerianate  of 
sodium,  cooling,  separating  the  white  pearly  crystalline 
matter,  evaporating  at  200°  to  a low  bulk,  cooling,  again 
separating  the  lamellar  crystals,  washing  the  whole  pro- 
duct with  a small  quantity  of  cold  distilled  water,  drain- 
ing and  drying  by  exposure  to  air  at  ordinarj^  tempera- 


114 


THE  METALLIC  RADICALS. 


tures.  Valerianate  of  zinc  is  soluble  in  ether,  alcohol,  or 
hot  water. 

ZnSO,  + 2NaC,H,0,  = Na,SO,  + Zn2C3H,0, 

Sulphate  Valerianate  of  Sulphate  of  Valerianate 

of  zinc.  sodium.  sodium.  of  zinc. 

jSfote. — The  compounds  of  zinc  described  in  the  above  six  reac- 
tions are  the  only  ones  mentioned  in  the  British  Pharmacopoeia  ; the 
processes  are  also  those  of  that  work.  Sulphide  and  Hydrate  of 
Zinc  are  mentioned  in  the  following  analytical  paragraphs.  The 
formula  of  Sulphite  of  Zinc  is  ZnS 03,31120. 

(h)  Reactions  having  Analytical  Interest  (Tests). 

First  Analytical  Reaction. — To  solution  of  a zinc  salt 
(sulphate  for  example)  in  a test-tube,  add  solution  of  sul- 
ph^^drate  of  ammonium  (NH^HS)  ; white  sulphide  of  zinc 
(Z'nS)  is  precipitated,  insoluble  in  acetic,  but  soluble  in  the 
stronger  acids. 

JSfote. — This  is  the  only  white  sulphide  that  will  be  met  with.  Its 
formation,  on  the  addition  of  the  sulphydrate  of  ammonium,  is  there- 
fore highly  characteristic  of  zinc.  If  the  zinc  salt  contains  iron  or 
lead  as  impurities,  the  precipitate  will  have  a dark  appearance,  the 
sulphides  of  those  metals  being  black.  Hydrate  of  aluminium,  which 
is  also  white  and  precipitated  by  sulphydrate  of  ammonium,  is  the 
only  substance  sulphide  of  zinc  is  likely  to  be  mistaken  for,  and  vice 
vers  i ; but,  as  will  be  seen  immediately,  there  are  good  means  of 
distinguishing  these  from  each  other. 

Second  Analytical  Reaction. — To  solution  of  a zinc  salt 
add  solution  of  ammonia  ; white  hydrate  of  zinc  (Zn2H0) 
is  precipitated.  Add  excess  of  ammonia  ; the  preci[)itate 
is  redissolved. 

This  reaction  at  once  distinguishes  a zinc  salt  from  an  aluminium 
salt,  hydrate  of  aluminium  being  insoluble  in  ammonia. 

Other  Analytical  Reactions. — The  fixed  alkali-hydrates 
afford  a similar  reaction  to  that  just  mentioned,  the  hydrate 

of  zinc  redissolving  if  the  alkali  is  free  from  carbonate. 

Carbonate  of  ammonium  yields  a white  precipitate  of  car- 
bonate and  hydrate,  soluble  in  excess. The  fixed  alka- 

line carbonates  give  a similar  precipitate,  which  is  not 
redissolved  if  the  mixed  solution  and  precipitate  be  well 

boiled. Ferrocyanide  of  potassium  precipitates  white 

ferrocyanide  of  zinc  (Zn.^FeCyg). 

Sulphate  of  magnesium,  which  is  isomorphous  with  and 
indistinguishable  in  appearance  from  sulphate  of  zinc,  is 
not  precipitated  from  its  solutions  either  by  ferrocyanide 
of  potassium  or  sulphydrate  of  ammonium. 


ALUMINIUM. 


115 


Antidotes. — There  are  no  efficient  chemical  means  of  counteract 
ing-  the  poisonous  effects  of  zinc.  Large  doses,  fortunately,  act  as 
. powerful  emetics.  If  vomiting  has  not  occurred,  or  apparently  to  ,/ 
an  insufficient  extent,  solution  of  carbonate  of  sodium  (common  wash- 
ing salt)  immediately  followed  by  white  of  egg  and  demulcents  may 
be  administered. 


QUESTIONS  AND  EXERCISES. 

185.  Give  the  sources  and  uses  of  metallic  zinc. 

186.  Explain  by  a diagram  what  occurs  when  zinc  is  dissolved  in 
dilute  sulphuric  acid. 

187.  How  may  solutions  of  Chloride  of  Sulphate  of  Zinc  be  puri- 
fied from  salts  of  iron  ? Give  equations  descriptive  of  the  reactions. 

188.  State  the  formula  of  Carbonate  of  Zinc,  and  illustrate  by  a 
diagram  the  reaction  which  takes  place  in  its  production. 

189.  Give  an  equation  showing  the  formation  of  Acetate  of  Zinc. 

190.  In  what  respect  does  Oxide  of  Zinc,  resulting  from  the  igni- 
tion of  the  carbonate,  differ  from  that  produced  during  the  combus- 
tion of  the  metal  ? 

191.  How  is  Valerianate  of  Zinc  prepared? 

192.  What  are  the  properties  of  Valerianate  of  Zinc. 

193.  Name  the  more  important  tests  for  zinc. 

194.  How  would  you  distinguish,  chemically,  between  solutions  of 
Sulphate  of  Zinc  and  Alum  ? 

195.  Describe  the  treatment  in  cases  of  poisoning  by  salts  of  zinc. 

196.  Give  reactions  distinguishing  Sulphate  of  Zinc  from  Sulphate 
of  Magnesium. 

ALUMINIUM. 

Symbol  Al.  Atomic  weight  27.5. 

Note. — In  the  formulae  of  aluminium  salts,  it  will  be  observed  that 
to  one  atom  of  metal  there  are  three  atoms  of  other  univalent  radi- 
cals ; hence,  apparently,  the  atom  of  aluminium  is  trivalent,  Al'". 
But  possibly  it  is  quadrivalent ; for  one  molecule  of  aluminium  com- 
pounds includes  two  atoms  of  the  metal,  three-fourths  only  of  whose 
power  may  be  supposed  to  be  exerted  in  retaining  the  other  constitu- 
ents of  the  molecule,  the  remaining  fourth  enabling  the  aluminium 
atoms  themselves  to  keep  together.  This  is  graphically  shown  in 
the  following  formula  of  chloride  of  aluminium  (Al^Clg)  from  Frank- 
land’s  “ Lecture  Notes  for  Chemical  Students,"  which  represents  each 

Cl  Cl 

Cl-Al-  Al-Cl 

I I 

Cl  Cl 

aluminium  atom  as  a body  having  four  arms  or  bonds,  three  of  which 
are  engaged  in  grasping  the  arms  of  univalent  chlorine  atoms,  while 


116 


THE  METALLIC  RADICALS. 


the  fourth  grasps  the  corresponding  arm  of  its  brother  aluminium 
atom.  Such  graphic  formulae,  as  they  are  called,  are  useful  in 
facilitating  the  acquirement  of  hypotheses  regarding  the  constitution 
of  chemical  substances,  especially  if  the  error  be  avoided  of  suppos- 
ing that  they  are  pictures  either  of  the  position  or  absolute  power 
of  atoms  in  a molecule,  or  indeed,  the  true  representation  of  a mole- 
cule at  all ; for  on  this  point  man  knows  little  or  nothing. 

Source. — Aluminium  is  very  abundant  in  nature,  chiefly  as  sili- 
cate, in  clays,  slate,  marl,  granite,  basalt,  and  a large  number  of 
minerals.  The  sapphire  and  ruby  are  almost  pure  oxide  of  aluminium. 
The  metal  is  obtained  from  the  double  chloride  of  aluminium  and 
sodium,  by  the  action  of  metallic  sodium,  the  source  of  the  chloride 
being  the  miueral  bauxite. 

Aluminium-bronze  is  an  alloy  of  ten  parts  of  aluminium  with 
ninety  of  copper. 

Alum  [Alumen,  B.  P.  and  U.  S.  P.),  a double  sulphate  of  alumi- 
nium and  ammonium  (Al23SO^,  Am2S04,  24H2O),  may  be  obtained 
from  aluminous  schist  (from  scliisios,  divided)  a sort  of  pyri- 

tous  slate  or  shale,  by  exposure  to  air ; oxidation  and  chemical  change 
produce  sulphate  of  aluminium,  sulphate  of  iron,  and  silica,  from  the 
silicate  of  aluminium  and  bisulphide  of  iron  (iron  pyrites)  originally 
present  in  the  shale.  The  sulphate  of  aluminium  and  sulphate  of 
iron  are  dissolved  out  of  the  mass  by  water,  and  sulphate  or  chloride 
of  ammonium  added ; on  concentrating  the  liquid,  alum  cyrstallizes 
out,  while  the  more  soluble  iron  salt  remains  in  the  mother-liquor. 

Alum  is  also  prepared  by  directly  decomposing  the  silicate  of 
aluminium  in  the  calcined  shale  of  the  coal-measures  by  hot  sulphuric 
acid,  ammonia  being  added  from  time  to  time  until  a solution  strong 
enough  to  crystallize  is  obtained.  The  liquid  well  agitated  during 
cooling  deposits  alum-flour,  which  is  afterwards  recrystallized. 

Alums. — There  are  several  alums,  iron  or  chromium  replacing 
aluminium,  and  potassium  or  sodium  taking  the  place  of  ammonium, 
all  crystallizing  in  an  eight-sided  form,  the  octahedron — a sort  of 
double  pyramid.  These  are,  apparently,  alike  in  chemical  consti- 
tution, and  their  general  formula  (M  = either  metal)  is  M'"2flS04, 
M'2S04,  24H2O.  The  alum  of  the  manufacturer  commonly  occurs  in 
colorless,  transparent,  octahedral  crystals,  massed  in  lumps,  which 
are  roughly  broken  up  for  trade  purposes,  but  still  exhibit  the  faces 
of  octahedra. 

Sulphate  of  Aluminium  (AI23SO4,  9H2O),  or  Alum  Cake,  pre- 
pared from  natural  silicates  in  the  manner  just  described,  is  a com- 
mon article  of  trade,  serving  most  of  the  manufacturing  purposes  for 
which  alum  was  formerly  employed.  In  the  United  States  Pharma- 
copoeia {Aluminii  Sulphas)  it  is  directed  to  be  made  by  dissolving 
hydrate  of  aluminium  in  diluted  sulphuric  acid  with  subsequent  re- 
moval of  water  by  evaporation. 

AI26HO  + 3H2SO4  = AI23SO4  + 6H2O. 

The  hydrate  of  aluminium  is  to  be  prepared  by  the  addition  of  solu- 
tion of  alum  to  solution  of  carbonate  of  sodium,  the  precipitated 
hydrate  being  collected  on  a filter  and  well  washed. 


ALUMINIUM. 


in 


A1,3S0„  Am, SO,  4-  3Na,C03  + 3H,0  = A1,6H0  + Am,SO,  + 
3Na,S0,  + 300,. 

Preparation  of  Alum. — Prepare  alum  by  heating  a small  quan- 
tity of  powdered  pipeclay  (silicate  of  aluminium)  with  about  twice 
its  weight  of  sulphuric  acid  for  some  time,  dissolving  out  the  result- 
ing sulphate  of  aluminium  and  excess  of  sulphuric  acid  by  water,  and 
adding  only  ammonia  to  the  clear-filtered  solution  until,  after  well 
stirring,  the  excess  of  acid  is  neutralized.  (If  too  much  ammonia 
be  added  the  hydrate  of  aluminium  precipitated  when  the  ammonia 
is  first  poured  in  will  not  be  redissolved  on  well  mixing  the  whole. 
Perhaps  the  readiest  indication  of  neutrality  in  this  and  similar  cases 
is  the  presence  of  a little  precipitate  after  stirring  and  warming  the 
mixture.)  On  evaporating  the  clear  solution,  crystals  of  alum  are 
obtained. 

The  Ammonio ferric  Alum  of  American  pharmacy  [Ferri  et 
Ammonii  Sulphas,  U.  S.  P.)  is  made  by  adding  sulphate  of  ammo- 
nium to  a hot  solution  of  persulphate  of  iron,  and  setting  the  liquid 
aside  to  crystallize.  It  forms  pale  violet  octahedral  crystals,  ex- 
pressed by  the  formula  Fe43SO„  (NH,)2S04,  2411,0.  Aluminii  et 
Potassii  Sulphas  (U.  S.  P.)  is  potassium  alum,  the  sulphate  of  alu- 
minium and  potassium  (Al^SSO,,  K2SO4,  24H2O). 

Dried  Alum  [Alumen  Exsiccatum,  B.  P.  and  U.  S.  P.)  is  alum 
from  which  the  water  of  crystallization  has  been  expelled  by  heat, 
the  temperature  not  exceeding  400°.  By  calculation  from  the  mole- 
cular weight  of  alum,  it  will  be  found  that  the  salt  contains  between 
47  and  48  per  cent,  of  water.  At  temperatures  above  400^  alum  is 
decomposed,  sulphate  of  ammonium  and  sulphuric  anhydride  escap- 
ing, and  pure  alumina  (AI2O3)  remaining.  Dried  alum  rapidly 
reabsorbs  water  from  the  atmosphere.  It  is  almost  useless  as  a 
medicinal  preparation. 

Roche  alum,  or  Rode  alum  {roche,  French,  rock),  is  the  name  of  an 
impure  native  variety  of  alum  containing  iron.  The  article  sold 
under  this  name  is  an  artificial  mixture  of  common  alum  with  oxide 
of  iron. 


Reactions  having  Analytical  Interest. 

First  Analytical  Reaction, — To  a solution  of  an  aluminium 
salt  (alum,  for  example,  which  contains  sulphate  of  alumi- 
nium) add  sulphj'drate  of  ammonium  (NH^HS);  a gelati- 
nous white  precipitate  of  hydrate  of  aluminium  falls  : — 

Al,3SO,  -f  6AmHS  + 6H2O  = Al,6HO  + 3 Am^SO,  + 6H^S. 

Second  Analytical  Reaction. — To  solution  of  alum  add 
ammonia,  NH,HO  ; hydrate  of  aluminium  falls:  add  excess 
of  ammonia;  the  precipitate  is  insoluble. 

Principle  of  Dyeing  by  help  of  Mordants. — The  precipi- 
tated hydrate  of  aluminium,  or  alumina,  has  great  affinity 
for  vegetable  coloring-matters,  and  also  for  the  fibre  of 


118 


THE  METALLIC  RADICALS. 


cloth.  Once  more  perform  the  above  experiment,  but  be- 
fore adding  the  ammonia  introduce  some  decoction  of  log- 
wood, solution  of  cochineal,  or  other  similar  colored  liquid, 
into  the  test-tube.  Add  now  the  ammonia,  and  set  the 
tube  aside  for  the  alumina  to  fall ; the  latter  takes  down 
with  it  all  the  coloring  principle.  In  dye-works  the  fabrics 
are  passed  through  liquids  holding  the  alumina  but  weakly 
in  solution,  and  then  through  the  coloring  solutions ; from 
the  first  bath  the  fibres  abstract  alumina,  and  from  the 
second  the  alumina  abstracts  coloring  matter.  Some  other 
metallic  hydrates,  notably  those  of  tin  and  iron,  resemble 
alumina  in  this  property  ; the}’  are  all  termed  mordants 
(from  mordens^  biting)  ; the  substances  they  form  with 
coloring-matters  have  the  name  of  lakes. 

Third  Analytical  Reaction, — To  the  alum  add  solution 
of  potash;  again  hydrate  of  aluminium  falls.  Add  excess 
of  potash,  and  agitate  ; the  precipitate  dissolves. 

Alumina  may  be  precipitated  from  this  solution  by  neu- 
tralizing the  potash  with  hydrochloric  acid,  and  adding 
ammonia  until,  after  shaking,  the  mixture  has  an  ammoni- 
acal  smell,  or  by  adding  solution  of  chloride  of  ammonium 
to  the  potash  liquid.  But  the  former  way  is  the  better ; 
for  it  is  difficult  to  know  when  a sufficiency  of  the  chloride 
of  ammonium  has  been  poured  in,  whereas  reaction  with 
blue  and  red  litmus-paper  at  once  enables  the  operator  to 
know  when  excess  of  hydrochloric  acid  or  ammonia  has 
been  added. 

Alkaline  carbonates,  phosphates,  arseniates,  and  salts  of  other  aci- 
dulous radicals  also  decompose  solutions  of  aluminium  salts  and  pro- 
duce insoluble  compounds  of  that  metal,  with  the  several  acidulous 
radicals  (except  the  carbonic),  but  the  resulting  precipitates  are  of 
no  special  interest. 


QUESTIONS  AND  EXERCISES. 

197.  What  is  there  remarkable  about  the  quanti valence  of  alumi- 
nium? 

198.  Practically  what  is  the  quantivalence  of  the  atom  of  alumi- 
nium ? 

199.  Enumerate  the  chief  natural  compounds  of  aluminium. 

200.  Write  down  a formula  which  will  represent  either  of  the 
Alum’s. 

201.  Which  alum  is  official,  and  commonly  employed  in  the  arts  ? 

202.  State  the  source,  and  explain  the  formation  of  alum. 

203.  What  is  the  crystalline  form  of  alum  ? Work  a sum  showing 


IRON. 


119 


how  much  Dried  Alum  is  theoretically  producible  from  100  pounds 
of  alum  ? Ans.  52  lbs.  6 ozs. 

204.  Show  by  figures  how  ordinary  ammonium  alum  is  capable  of 
yielding  11.356  per  cent,  of  alumina. 

205.  Why  are  aluminium  compounds  used  in  dyeing  ? 

206.  How  are  salts  of  aluminium  analytically  distinguished  from 
those  of  zinc  ? 

IRON. 

Symbol  Fe.  Atomic  weight  56. 

Sources. — Compounds  of  iron  are  very  abundant  in  nature.  Mag- 
netic Iron  Ore,  or  Loadstone  [Lodestone  or  Leadstone,  from  the 
Saxon  Icedan,  to  lead,  in  allusion  to  its  use,  or  rather  of  magnets  made 
from  it,  in  navigation),  is  the  chief  ore  from  which  Swedish  iron  is 
made  ; it  is  a mixture  of  ferrous  and  ferric  oxide  (Fe0,Fe203).  Much 
of  the  Russian  iron  is  made  from  Specidar  Iron  Ore  (from  speculum, 
a mirror,  in  allusion  to  the  lustrous  nature  of  the  crystals  of  this 
mineral).  This  and  Red  Haematite  (from  al^a,  liaima,  blood,  so 
named  from  the  color  of  its  streak)  an  ore  raised  in  Lancashire,  are 
composed  of  ferric  oxide  only  (Fe203).  Brown  Haematite,  an  oxy- 
hydrate,  is  the  source  of  much  of  the  French  iron.  Spathic  Iron 
Ore  (from  spatha,  a slice,  in  allusion  to  the  lamellar  structure  of  the 
ore)  is  a ferrous  carbonate  (FeCOg).  An  impure  ferrous  carbonate 
forms  the  Clay  Ironstone,  whence  most  of  the  English  iron  is  derived. 
The  chief  Scotch  ore  is  also  an  impure  carbonate,  containing  much 
bituminous  matter ; it  is  known  as  Black  Band.  Iron  Pyrites  (from 
Ttvp,  pur,  fire,  in  allusion  to  the  production  of  sparks  when  sharply 
struck)  (FeS2)  is  a yellow  lustrous  mineral,  of  use  only  for  its  sul- 
phur. Ferrous  carbonate  (FeCOy),  chloride  (FeCl2,4H2^)5 
phate  (FeS04,7H20)  sometimes  occur  in  springs,  the  water  of  which 
is  hence  termed  chalybeate  [chalybs,  steel). 

Process. — Iron  is  obtained  from  its  ores  by  processes  of  roasting, 
and  reduction  of  the  resulting  impure  oxide  with  coal  or  charcoal  in 
the  presence  of  chalk,  the  latter  uniting  with  the  sand,  clay,  etc.,  to 
form  a fusible  slag.  The  cast  iron  thus  produced  is  converted  into 
ivrought  iron  [Ferrum,  U.  S.  P)  by  burning  out  the  4 or  5 per 
cent,  of  carbon,  silicon,  and  other  impurities  present,  by  oxidation 
in  a furnace,  an  operation  which  is  termed  puddling.  Steel  is  wrought 
iron  impregnated  with  from  one  to  two  per  cent,  of  carbon  by  strongly 
heating  in  charcoal.  The  official  variety  of  the  metal  [Ferrum, B.  P.), 
the  condition  in  which  it  is  most  easily  employed  for  conversion  into 
its  compounds,  is  “ wrought  iron  in  the  form  of  wire  or  nails  free  from 
oxide.”  In  the  form  of  a fine  powder  (see  17  Reac.)  metallic  iron  is 
employed  as  a medicine. 

Properties. — The  specific  gravity  of  pure  iron  is  7.844,  of  the  best 
bar  iron  7.7  ; its  color  is  bluish-white  or  gray.  Bar  iron  requires  the 
highest  heat  of  a wind-furnace  for  fusion,  but  below  that  temperature 
assumes  a pasty  consistence,  and  in  that  state  two  pieces  may  be 
joined  or  welded  (Germ,  wellen,  to  join)  by  the  pressure  of  blows 
from  a hammer.  A little  sand  thrown  on  to  the  hot  metal  facilitates 


120 


THE  METALLIC  RADICALS. 


this  operation  by  forming  with  the  superficial  oxide  of  iron  a fusible 
slag,  which  is  dispersed  by  the  blows  : the  purely  metallic  surfaces 
are  thus  better  enabled  to  come  into  thorough  contact  and  enter  into 
perfect  union.  Iron  is  highly  ductile,  and  of  all  common  metals  pos- 
sesses the  greatest  amount  of  tenacity.  At  a high  temperature  it 
burns  in  the  air,  forming  oxide  of  iron.  Rust  of  iron  is  chiefly  red 
oxide  of  iron,  with  a little  ferrous  oxide  and  carbonate ; it  is  pro- 
duced by  action  of  the  moist  carbonic  acid  of  the  air  and  subsequent 
oxidation.  Steam  passed  over  scrap  iron  heated  to  redness  gives 
hydrogen  gas  and  black  oxide  of  iron. 

Quantivalence. — Iron  combines  with  other  elements  and  radicals 
in  two  proportions ; those  salts  in  which  the  atom  of  iron  appears  to 
possess  inferior  affinities  (in  which  the  other  radicals  are  in  the  less 
amount)  are  termed  ferrous,  the  higher  being  ferric  salts.  In  the 
former  the  iron  exerts  bivalent  (Fe"),  in  the  latter  trivalent  activity 
(Fe'"  or  Fe./i). 

The  atom  of  iron  is  also  sometimes  considered  to  be  sexivalent,  on 
account  of  the  analogy  of  its  compounds  with  those  of  chromium, 
wffiich  is  sexivalent,  if  the  formula  of  its  fluoride  (CrFg)  be  correct, 
and  because  the  composition  oi  ferrate  of  potassium  (KjFeO^),  a 
deep-purple  salt  obtained  on  passing  chlorine  through  a concentrated 
solution  of  potash  in  which  fresh  ferric  hydrate  is  suspended,  is  best 
explained  on  the  assumption  of  the  sexivalence  of  its  iron. 

Why  the  quantivalence  of  the  atom  of  iron  should  vary  is  not  at 
present  known. 

The  Nomenclature  of  Iron  Salts. — For  educational  and  descrip- 
tive purposes  the  two  classes  of  iron  compounds  are  very  conveniently 
spoken  of  as  ferrous  and  ferric,  the  syllable  '^ferr'"  common  to  all 
indicating  their  allied  ferruginous  character,  the  syllable  ous  and  ic 
indicating  the  lower  and  higher  class  respectively — functions  fulfilled 
by  these  two  syllables  in  other  similar  cases  (sulphurous  and  sulphu- 
ric, mercurous  and  mercuric).  Officially  the  iron  s^lts  are  known  by 
other  names,  thus.  Sulphate  of  Iron  (Ferri  Sulphas),  and  Phos- 
phate of  Iron  [Ferri  Phosphas),  names  which  are  chemically  inex- 
plicit, for  there  are  two  sulphates,  and  two  phosphates,  and  the  terms 
do  not  define  which  salt  is  intended.  Consistency  and  uniformity 
would  demand  that  the  names  Ferrous  Sulphate,  Ferrous  Phosphate, 
or  similar  terms  should  be  employed.  Practically,  however,  the  old 
names  cause  no  confusion,  inasmuch  as  only  one  sulphate,  phosphate, 
etc.,  are  used  in  medicine ; moreover,  the  higher  salts  usually  have 
the  prefix  per  attached  (as  persulphate,  perchloride).  These  names 
are  already  well  known,  can  be  easily  rendered  in  Latin,  and  then 
admit  of  simple  abbreviations  and  adaptations  such  as  are  employed 
' in  prescriptions,  advantages  not  possessed  by  the  more  rational  terms. 
While,  therefore,  the  comprehension  of  the  chemistry  of  iron  is  ren- 
dered simple  and  intelligible  by  the  use  of  the  terms  ferrous  and 
ferric,  the  employment  of  older  and  less  definite  names  may  very  well 
be  continued  in  pharmacy  as  being  practically  more  convenient. 


IRON. 


121 


Reactions  having  (a)  Synthetical  and  (b)  Analytical 
Interest. 

(a)  Synthetical  Reactions. 

FERROUS  SALTS. 

Green  Sulphate  of  Iron.  Ferrous  Sulphate. 

First  Synthetical  Reaction, — Place  iron  (small  tacks)  in 
sulphuric  acid  diluted  with  eight  times  its  bulk  of  water 
(in  a test-tube,  basin,  or  other  vessel  of  any  required  size), 
accelerating  the  action  by  heat  until  effervescence  ceases. 

Fe,  + 2H,SO,  = 2FeSO,  -f  2H., 

Iron.  Sulphuric  Ferrous  Hydrogen, 

acid.  sulphate. 

The  solution  contains  what  is  generally  known  as  Sul- 
phate of  Iron,  that  is.  Ferrous  Sulphate,  the  lower  of  the 
two  sulphates,  and  will  yield  crystals  of  that  substance 
(FeS0^,7Il20)  {Ferri  Sulphas,^  B.  P.  and  U.  S.  P.)  on  cool- 
ing or  on  further  evaporation;  or  if  the  hot  concentrated 
solution  be  poured  into  alcohol,  the  mixture  being  well 
stirred,  the  sulphate  is  at  once  thrown  down  in  minute 
crystals  {Ferri  Sulphas  Granulata^  B.  P.).  At  a tempera- 
ture of  400°  F.  ferrous  sulphate  loses  six-sevenths  of  its 
water,  and  becomes  the  Ferri  Sulphas  Fxsiccata^  B.  P. 


Other  Sources  of  Ferrous  Sulphate. — In  the  laboratory,  ferrous 
sulphate  is  often  obtained  as  a by-product  in  making  sulphuretted 
hydrogen, 

FeS  + H^SO,  = H^S  -f  FeSO,. 

In  manufactories  it  occurs  as  a by-product  in  the  decomposition  of 
aluminous  shale,  as  already  noticed  (p.  116). 

Ten  grains  of  granulated  sulphate  of  iron  dissolved  in  one  ounce 
of  water  constitutes  “Solution  of  Sulphate  of  Iron,’^  B.  P.  “ The 
solution  should  be  recently  prepared.” 

Notes. — Ferrous  sulphate  is  sometimes  termed  green  vitriol. 
Vitriol  (from  vitrum,  glass)  was  originally  the  name  of  any  trans- 
parent crystalline  substance,  but  afterwards  restricted  to  the  sul- 
phates of  zinc,  iron,  and  copper,  which  were,  and  still  are,  occasion- 
ally known  as  white,  green,  and  blue  vitriol.  Copperas  (probably 
originally  Copper-rust,  a term  applied  to  verdigris  and  other  green 
incrustations  of  copper)  is  another  name  for  this  sulphate  of  iron, 
sometimes  distinguished  as  green  copperas,  sulphate  of  copper  being 
blue  copperas.  Solid  sulphate  of  iron  is  a constituent  of  Pilula 
Aloes  et  Ferri,  B.  P. 

Ferrous  sulphate,  when  exposed  to  the  air,  gradually  turns  brown 

11 


122 


THE  METALLIC  RADICALS. 


through  absorption  of  oxygen,  ferric  oxysulphate  (Fe202S04)  being 
formed.  The  latter  is  not  completely  dissolved  by  water,  owing  to 
the  formation  of  a still  lower  insoluble  oxysalt  (Fe^O-SO^)  and  solu- 
ble ferric  sulphate  5(Fe202S04)  = Fe405S04  -h  3(Fe23S04). 

Iron  heated  with  undiluted  sulphuric  acid  gives  sulphurous  acid 
gas  and  ferrous  sulphate  : — 

Fe2  + 4H2SO4  = SO2  + FeSO^  + 2H2O. 

Carbonate  of  Iron.  Ferrous  Carbonate. 

Second  Synthetical  Reaction. — To  solution  of  ferrous 
sulphate,  boiling,  in  a test-tube,  add  a solution  of  carbonate 
of  ammonium  (Am2C03,  etc.)  in  recently  boiled  water  ; a 
white  precipitate  of  ferrous  carbonate  (FeCOg)  is  thrown 
down,  rapidly  becoming  light  green,  bluish-green,  and,  after 
a long  time,  red,  through  absorption  of  oxygen,  evolution 
of  carbonic  acid  gas,  and  formation  of  ferric  oxyhydrate. 

FeSO^  + Am2C03  = FeCOg  + Am2S04 

Ferrous  Carbonate  of  Ferrous  Sulphate  of 

sulphate.  ammonium.  carbonate.  ammonium. 

Saccharated  Carbonate  of  Iron. — The  above  precipitate,  rapidly 
washed  with  hot  well-boiled  distilled  water,  and  the  moist  powder 
mixed  with  sugar  and  quickly  dried — in  short,  all  possible  precau- 
tions taken  to  avoid  exposure  to  air — forms  the  saccharated  carbo- 
nate of  iron  [Ferri  Carhonas  Saccharata,  B.  P.). 

The  official  proportions  are  two  ounces  of  the  sulphate  and  one 
ounce  and  a quarter  of  the  carbonate,  each  dissolved  in  half  a gallon 
of  hot  water ; the  solutions  are  mixed  and  set  aside  in  a deep  well- 
covered  pan,  the  supernatant  liquid  poured  off  when  the  precipitate 
has  subsided,  the  pan  again  filled  up  with  boiling  water,  the  liquid 
once  more  poured  away,  the  precipitate  transferred  to  a calico  filter, 
drained,  gently  pressed,  and  while  still  somewhat  moist  rubbed  in  a 
mortar  with  one  ounce  of  sugar,  and  finally  dried  over  a water-bath. 

Carbonate  of  Iron,  mixed  with  a fourth  its  w^eight  of  Confection 
of  Roses  (Honey  and  Sugar,  U.  S.  P.),  forms  the  Pilula  Ferri  Car- 
honatis,  B.  P.  and  U.  S.  P. 

Notes. — The  Subcarbonate  of  Iron  [Ferri  Subcarbonas,  U.  S.  P.) 
is  precipitated  on  mixing  solutions  of  sulphate  of  iron  and  carbonate 
of  sodium.  On  washing  and  drying  it  is  converted  into  reddish- 
brown  oxyhydrate  of  iron,  water  being  absorbed  and  carbonic  acid 
gas  being  eliminated.  This  oxyhydrate  of  iron  is  best  made  by  pre- 
cipitating solution  of  persulphate  of  iron  by  solution  of  soda,  and 
washing  and  drying  the  product  (see  page  127). 

Saccharated  ferrous  carbonate  is  said  to  be  more  easily  dissolved 
in  the  stomach  than  any  other  iron  preparation.  It  is  so  unstable 
and  prone  to  oxidation,  that  it  must  be  washed  in  w^atcr  containing 
no  dissolved  air  and  mixed  with  the  sugar  (which  protects  it  from 
oxidation)  as  quickly  as  possible.  In  making  the  official  compound 
mixture  of  iron  [Mistura  Ferri  Composita.  B.  P.  and  U.  S.  P.), 


IRON. 


123 


Griffith’s  mixture,”  the.  various  ingredients,  including  the  carbonate 
of  potassium,  should  be  placed  in  a bottle  of  the  required  size,  space 
being  left  for  the  crystals  or  solution  of  ferrous  sulphate,  which 
should  be  added  last,  the  bottle  immediately  filled  up  with  rose- 
water, and  securely  corked ; oxidation  is  thus  prevented  to  the 
greatest  possible  extent.  Pihdce  Ferri  Compositce,  U.  S.  P.,  is 
made  from  myrrh,  carbonate  of  sodium,  sulphate  of  iron  and  syrup  ; 
carbonate  of  iron  is  gradually  formed. 

FeSO,  + K,C03  = FeC03  + K^SO^ 

Ferrous  Carbonate  of  Ferrous  Sulphate  of 

sulphate.  potassium.  carbonate.  potassium. 

Arseniate  of  Iron.  Ferrous  Arseniate. 

Third  Synthetical  Reaction^  by  which  the  lower  arseniate 
of  iron,  ferrous  arseniate  {Ferri  Arsenias,  B.  P.)  (Fe3 
2J^  sOJ,  partiall}’  oxidized,  is  formed.  This  will  be  noticed 
again  under  Arsenicum. 


Phosphate  of  Iron.  Ferrous  Phosphate. 

Fourth  Synthetical  Reaction. — To  solution  of  ferrous 
sulphate  in  a test-tube  add  a little  solution  of  acetate  of 
sodium,  then  solution  of  phosphate  of  sodium ; the  lower 
phosphate  of  iron,  ferrous  phosphate  (Fe32PO^),  is  precipi- 
tated {Ferri  Phosphas^  B.  P.  and  U.  S.  P.). 

3FeSO,  -f  2NaJIPO,  + 

Ferrous  Phosphate  of  Acetate  of 

sulphate.  sodium.  sodium. 

= Fe32PO,  + 3Na,SO,  + 2HC,H30, 

Ferrous  Sulphate  of  Acetic  acid, 

phosphate.  sodium. 

Officially,  solutions  of  3 ounces  of  sulphate  of  iron  in  a quart  of 
water,  and  2^  ounces  of  phosphate  and  1 of  acetate  of  sodium  in 
another  quart  of  water,  are  well  mixed,  filtered,  the  precipitate  well 
washed,  and,  to  prevent  oxidation  as  much  as  possible,  dried  at  a 
temperature  not  exceeding  120^  F.  These  proportions  will  be  found 
to  accord  with  the  molecular  weights  of  the  crystalline  salts,  multi- 
plied as  indicated  in  the  foregoing  equation.  3(FeS04,  7H^O)=834; 
2(Na,HP04,  12H20)=716;  2(Na02H302,  3H20)=272. 

The  use  of  the  acetate  of  sodium  (not  mentioned  in  the  U.  S.  P. 
formula)  is  to  insure  the  occurrence  of  acetic  acid  in  the  solution, 
where  otherwise  would  be  free  sulphuric  acid.  Sulphuric  acid  is  a 
solvent  of  ferrous  phosphate  ; acetic  acid  is  not.  It  is  impossible  to 
prevent  the  separation  of  sulphuric  acid,  if  only  ferrous  sulphate  and 
phosphate  of  sodium  be  employed.  Ferrous  phosphate  is  white,  but 
soon  oxidizes  and  becomes  slate-blue. 

The  above  reaction  also  occurs  in  making  Syrupus  Ferri  Plios- 
phatis,  B.  P.  The  precipitate  should  be  well  washed,  or  red  ferric 
acetate  may  be  developed  after  a time. 


124 


THE  METALLIC  RADICALS. 


Sulphide  of  Iron.  Ferrous  Sulphide. 

Fifth  Synthetical  Reaction, — In  a gas-  or  spirit-flame 
strongly  heat  about  twice  its  weight  of  iron 

filings  in  a test-tute'(<^  in  an  earthen  crucible  in  a furnace) ; 
ferrous  sulphide  (iTeS)  is  formed.  When  cold,  add  water 
to  a small  portion,  and  then  a few  drops  of  sulphuric  acid  ; 
sulphuretted  hydrogen  gas  (H^S),  known  by  its  odor,  is 
evolved. 

FeS  + H,SO,  = FeSO,  + H^S. 

Sticks  of  sulphur  pressed  against  a white-hot  bar  of  cast  iron  give 
the  purest  form  of  ferrous  sulphide.  The  liquid  sulphide  thus  formed 
is  allowed  to  drop  into  a vessel  of  water  (Sulphide  of  Iron,  B.  P. ; 
Ferri  Sulphuretum,  U.  S.  P.). 

Green  Iodide  of  Iron.  Ferrous  Iodide. 

. Sixth  Synthetical  Reaction, — Place  a piece  of  iodine, 
about  the  size  of  a pea,  in  a test-tube  with  a small  quantity 
of  water,  and  add  a few^  iron  filings,  small  nails,  or  iron 
wire.  On  gently  warming,  or  merely  shaking  if  longer 
time  be  allow^ed,  the  iodine  disappears,  and,  on  filtering,  a 
clear  light  green  solution  of  iodide  of  iron  (Fel  J is  obtained. 

The  official  Ferri  lodidum  is  formed  by  gently  warming  a mix- 
ture of  3 parts  of  iodine,  of  fine  iron  wire,  and  12  of  distilled 
water  in  an  iron  vessel.  When  combination  is  nearly  complete  (as 
shown  by  indications  of  a sea-green  tint),  boil  for  a short  time  until 
the  whiteness  of  the  froth  proves  that  the  iodine  has  entirely  disap- 
peared. The  solution  is  then  filtered  and  evaporated  in  a clean  bright 
iron  saucepan,  ladle,  or  dish  until  a drop  taken  out  on  the  end  of  an 
iron  wire  stirrer  solidifies  on  cooling.  The  liquid  is  poured  out  on  a 
clean  smooth  slab,  broken  up  and  preserved  in  a glass-stoppered 
bottle.  Solid  iodide  of  iron  has  a crystalline  fracture,  is  “ green  with 
a tinge  of  brown  ; inodorous,  deliquescent,  and  almost  entirely  soluble 
in  water,  forming  a slightly  green  solution  which  gradually  deposits 
a colored  sediment  and  acquires  a red  color.” 

The  solid  iodide  contains  about  18  per  cent,  of  water  of  crystalliza- 
tion, and  a little  oxide  of  iron.  It  is  deliquescent  and  liable  to  absorb 
oxygen  from  the  air  with  formation  of  insoluble  ferric  oxyiodide  or 
hydrato-iodide.  Iodide  of  iron  thus  spoilt  may  be  purified  by  re-solu- 
tion in  water,  addition  of  a little  more  iodine  and  some  iron,  warming, 
filtering,  and  evaporating  as  before. 

Ferrous  bromide  (FeBr.,),  occasionally  used  in  medicine,  could  be 
made,  as  might  be  expected,  in  the  same  way  as  the  iodide. 


IRON. 


125 


FERRIC  SALTS. 

Anhydrous  Perchloride  of  Iron.  Ferric  Chloride. 

Seventh  Synthetical  Reaction — Pass  chlorine  (generated 
as  usual,  from  black  oxide  of  manganese  and  hydrochloric 
acid  in  a flask)  through  sulphuric  acid  contained  in  a small 
bottle,  and  thence  by  the  ordinary  narrow  glass  tubing  to 
the  bottom  of  a test-tube  containing  twenty  or  thirty  small 
iron  tacks  (or  a Florence  flask  containing  2 or  3 ounces  of 
iron  tacks),  the  latter  kept  hot  by  a gas-flame ; the  higher 
chloride  of  iron,  ferric  chloride,  or  the  perchloride*  of  iron 
(Fe2Clg)  is  formed  and  condenses  in  the  upper  part  of  the 
tube  or  flask  aa  a mass  of  small  dark  iridescent  crystals. 
When  a tolerably  thick  crust  of  the  salt  is  formed,  break 
off  the  part  of  the  glass  containing  it,  being  careful  that 
the  remaining  corroded  tacks  are  excluded,  and  place  it  in^ 
ten  or  twenty  times  its  weight  of  water ; the  resulting  solu- 
tion, poured  off*  from  any  pieces  of  glass,  is  a pure  neutral 
solution  of  hydrous  ferric  chloride,  and  will  be  serviceable 
in  performing  analytical  reactions. 

Precaution, — The  above  experiment  must  be  conducted  in  the 
open  air,  or  in  a cupboard  having  a draught  outwards. 

Anhydrous  Ferrous  Chloride. — In  breaking  up  the  tube,  small 
scales  of  a light  buff  color  will  be  observed  adhering  to  the  nails ; 
they  are  crystals  of  ferrous  chloride  (FeCd.,)* 

Note. — Solution  of  ferric  chloride  evolves  some  hydrochloric  acid 
on  boiling,  while  a darker- colored  solution  of  ferric  oxychloride 
remains. 

Green  Chloride  of  Iron.  Hydrous  ferrous  Chloride.  Solution 
of  Hydrous  Ferric  Chloride. 

Eighth  Synthetical  Reaction, — Dissolve  iron  tacks,  in  a 
test-tube,  in  hydrochloric  acid  ; hydrogen  escapes,  and  the 
solution  on  cooling,  or  on  evaporation  and  cooling,  de- 
posits cry stallized  ferrous  chloride  (FeCl2,4H20), 

Through  a portion  of  the  solution  of  ferrous  chloride 
pass  chlorine  gas ; the  ferrous  chloride  becomes  ferric 
chloride* 

The  excess  of  chlorine  dissolved  by  the  liquid  in  this  experiment 
may  be  removed  by  ebullition  ; but  the  ferric  chloride  is  slightly  de- 

* The  prefixes  per  and  hyper  usedi  here  and  elsewhere  are  from  yTrep, 
hyper^  over  and  above,  and  simply  mean  “ the  highest”  of  several. 
Thus  perchloride,  the  highest  chloride, 

11* 


126 


THE  METALLIC  RADICALS. 


composed  at  the  same  time,  for  the  reason  just  stated.  The  free 
chlorine  may  also  be  carried  off*  by  passing  a current  of  air  through 
the  liquid  for  some  time. 

Hydrous  Ferric  Chloride  (another  process). 

Ninth  Synthetical  Reaction. — To  another  portion  of  the 
solution  of  ferrous  chloride,  in  a test-tube,  add  a little 
more  hydrochloric  acid ; heat  the  liquid,  and  continue  to 
drop  in  nitric  acid  until  the  black  color  it  first  produces 
disappears  ; the  resulting  reddish-brown  liquid  is  also  solu- 
tion of  ferric  chloride. 

6FeCT,  -f  2HNO3  + eilCl  = SFe.Clg  + 2NO  -f  mfl. 

Ferrous  Nitric  Hydrochloric  Ferric  Nitric  Water. 

chloride.  acid.  acid.  chloride.  oxide. 

The  black  color  is  due  to  solution  of  nitric  oxide  gas  (NO)  in  a 
portion  of  the  ferrous  salt ; it  is  decomposed  by  heat. 

This  is  the  process  for  producing  the  Liquor  Ferri  Perchloridi 
Fortior,  B.  P.,  2 ounces  of  iron,  12  fluidounces  of  hydrochloric  acid, 
9 fluidrachms  of  nitric  acid,  and  8 ounces  of  water  being  employed, 
and  the  product  boiled  down  to  10  fluidounces.  Practically  it  is 
impossible  so  to  apportion  the  acids  that  a solution  shall  result  con- 
taining neither  excess  of  acid  nor  of  metal,  nor  contain  ferric  nitrate. 
For  most  medicinal  purposes,  however,  solution  of  perchloride  of 
iron  containing  hydrochloric  acid  is  said  to  be  unobjectionable.  The 
Liquor  Ferri  Chloridi,  U.  S.  P.,  is  a similar  solution,  but  not  quite 
so  strong. 

Diluted  with  3 volumes  of  water  this  strong  solution  gives  the 
Liquor  Ferri  Perchloridi,  B.  P. — or  with  3 volumes  of  rectified 
spirit  the  Tinctura  Ferri  Perchloi'idi,  B.  P.  The  Tinctura  Ferri 
Chloridi,  U.  S.  P.,  is  a similar  solution. 

Note. — The  spirit  in  the  tincture  is  unnecessary,  useless,  and  dele- 
terious ; for  it  acts  neither  as  a special  solvent  nor  as  a preservative, 
the  offices  usually  performed  by  alcohol  ( Tincturce  et  Sued,  B.  P. 
and  U.  S.  P.) ; but,  unless  the  liquid  contain  excess  of  acid,  decom- 
poses the  ferric  chloride  and  causes  the  tbrmation  of  an  insoluble 
oxychloride  of  iron.  Even  if  the  tincture  be  acid,  it  slowly  loses 
color,  ferrous  chloride  and  chlorinated  ethereal  bodies  being  formed. 
A Liquor,  of  similar  strength,  is  doubtless  destined  to  displace  the 
tincture  altogether. 

Solution  of  ferric  chloride  evaporated  yields  a mass  of  yellow  crys- 
tals [Ferri  Chloridum,  U.  S.  P:)  containing  Fe2Clg,121l20,  or, 
rarely,  red  crystals  having  the  formula  Fe2Clg,5rf20.  An  old  method 
of  making  solution  of  ferric  chloride  is  to  dissolve  ferric  oxide  or 
hydrate  in  hydrochloric  acid ; but  from  the  varying  character  of 
trade  specimens  of  the  ingredients,  the  liquid  is  more  likely  to  con- 
tain excess  or  deficiency  of  iron  than  the  proper  proportion. 


IRON. 


12T 


Persulphate  of  Iron.  Ferric  Sulphate. 

Tenth  Synthetical  Reaction, — Dissolve  about  three-quar- 
ters of  an  ounce  of  ferrous  sulphate  and  a sixth  of  its 
weight  of  sulphuric  acid  in  an  ounce  and  a half  of  water 
in  an  evaporating  dish,  heat  the  mixture  and  drop  in  nitric 
acid  until  the  black  color  it  first  produces  disappears ; the 
resulting  liquid,  when  made  of  a certain  prescribed  strength, 
is  the  solution  of  ferric  sulphate,  or  higher  sulphate,  “ So- 
lution of  Persulphate  of  Iron’^  of  the  British  Pharmaco- 
poeia, a heavy  dark-red  liquid,  sp.  gr.  1.441.  The  Liquor 
Ferri  Tersulphatis,,  TJ.  S.  P.,  is  the  same  preparation,  but 
slightly  stronger  (sp.gr.  1.320).  Liquor  Ferri  Suhsulphatis,, 
U.  S.  P.  (MonsePs  solution),  is  a similar  fluid,  made  with 
less  acids,  probablj^  containing,  therefore,  ferric  oxy sul- 
phate and  ferric  oxynitrate  (sp.  gr.  1.552). 

6FeSO,  + 3H,SO,  + 2HNO3  = 3(Fe,3SOJ  + 2NO  + 4Hp. 

Ferrous  Sulphuric  Nitric  Ferric  Nitric  Water, 

sulphate.  acid.  acid.  sulphate.  oxide. 

The  black  color,  as  in  the  previous  reaction,  is  due  to  a compound 
of  ferrous  salt  with  nitric  oxide  (2FeS0^4-N0). 

Note. — In  all  the  reactions  in  which  iron  passes  from  ferrous  to 
ferric  condition  the  element  assumes  different  properties,  the  chief 
being  an  alteration  frorh  bivalent  to  trivalent  activity. 

Acetate  of  Iron.  Ferric  Acetate. 

Eleventh  Synthetical  Reaction, — To  a strong  solution  of 
ferric  sulphate  (from  which  free  nitric  acid  has  been  re- 
moved by  evaporating  to  dryness  and  redissolving  in  water) 
add  an  alcoholic  solution  of  acetate  of  potassium  (KC^H^ 
O.J,  and  well  shake  the  mixture ; a crystalline  precipitate 
of  sulphate  of  potassium  (K2SO4)  falls,  and  ferric  acetate 
(Fe^GCgS.^Og)  remains  in  solution,  forming,  when  filtered, 
and  of  definite  strength,  the  Tinctura  Ferri  AcetaHs.^  B.  P. 
The  preparation  is  unstable. 

Fe,3SO,  + + Fe,6C2H302 

Ferric  Acetate  of  Sulphate  of  Ferric 

sulphate.  potassium.  potassium.  acetate. 

The  official  proportions  are  2^  fluidounces  of  “ Solution  of  Per- 
sulphate of  Iron”  with  8 fluidounces  of  rectified  spirit,  mixed  with  a 
solution  of  2 ounces  of  acetate  of  potassium  in  10  fluidounces  of 
spirit,  the  whole  well  shaken  frequently  during  an  hour,  filtered,  and 
the  precipitated  sulphate  of  potassium  washed  by  pouring  on  spirit 
until  the  filtrate  measures  I pint.  A solution  four  times  this  strength, 
made  from  ferric  hydrate  and  glacial  acetic  acid,  is  stable.:  it  is  di- 
luted with  spirit  as  wanted  ( J.  Deane  and  T.  Jeaffreson). 


128w 


THE  METALLIC  RADICALS. 


Perhydrate  of  Iron.  Ferric  hydrate. 

Twelfth  Synthetical  Reaction. — Pour  a portion  of  the 
solution  of  ferric  sulphate  into  excess  of  solution  of  soda 
(ammonia,  U.  S.  P.) ; moist  ferric  hydrate  is  precipitated 
{Ferri  Peroxidum  Hiimidum^  B.  P.,  Ferri  Oxidum  Hydra- 
tun^  U.  8.  P.). 

Fe^SSO,  + 6NaHO  = Fe.^GHO  + 3Na,SO, 

Ferric  Soda.  Ferric  Sulphate 

sulphate.  hydrate.  of  sodium. 

Either  of  the  other  alkalies  (potash  or  ammonia)  will  produce  a 
similar  reaction ; but  soda  is  cheapest  and  most  convenient. 

Ferric  hydrate  is  an  antidote  to  arsenic  if  administered  directly 
the  poison  has  been  taken. 

It  converts  the  soluble  arsenic  (As^Og)  into  insoluble  ferrous  arse- 
niate : — 

2(Fe,6HO)  + ASA  = Fe32AsO,+  5H,0  4-  Fe2HO. 

Dried  ferric  hydrate  (then  become  an  oxyhydrate — Fe^O^IHO) 
[Ferri  Peroxidum  Hydratum,  B.  P.)  has  no  action  on  arsenic. 
Even  the  moist  recently  prepared  hydrate  (Fe.^GHO)  ceases  to  react 
with  arsenic  as  soon  as  it  has  become  converted  into  an  oxyhydrate 
(Fe^OyGHO),  a change  which  occurs  though  the  hydrate  be  kept 
under  water  (W.  Procter,  Jr.).  According  to  T.  and  H.  Smith  this 
decomposition  occurs  gradually,  but  in  an  increasing  ratio ; so  that 
after  four  months  the  power  of  the  moist  mass  is  reduced  to  one-half, 
and  after  five  months  to  one-fourth.  Now  mere  loss  of  water  is  not 
usually  followed  by  any  alteration  of  the  essential  chemical  proper- 
ties of  a compound.  It  would  seem,  therefore,  that  ferric  hydrate 
(two  molecules)  (Fe4l2I10)  probably  suffers,  on  standing,  actual 
decomposition  into  oxyhydrate  (Fe^OgGHO)  and  water  (3H^O),  and 
does  not  merely  lose  water  already  existing  in  it  as  water.  Ferric 
hydrate  is  also  far  more  readily  soluble  in  hydrochloric  acid,  tartaric 
acid,  citric  acid,  and  acid  tartrate  of  potassium,  than  ferric  oxyhy- 
drate. Any  formula  exhibiting  ferric  hydrate  (Fe.^GHO)  as  a com- 
bination of  ferric  oxide  and  water  (Fe^03,3II.^0)  is,  apparently,  for 
these  and  other  reasons,  incorrect. 

Peroxyhydrate  of  Iron.  Ferric  Peroxyhydrate. 

Collect  the  precipitate  on  a filter,  wash,  and  dry  on  a 
plate  over  hot  water;  ferric  oxyh^’drate  {Feri'i  Peroxidum 
Hydratum.^  B.  P.)  (Fe^0^2H0  j remains.  When  rubbed  to 
powder  it  is  fit  for  use  in  medicine. 

Fe^GIIO  ==  Fe,0.,2H0  + 211,0. 

This  oxyhydrate  further  decomposes  when  heated  to  low  redness, 
ferric  oxide  (Fe^Og)  remaining. 

Fe., 0,21 10  = re,03  + 11,0. 


IRON. 


129 


Peroxide  of  Iron.  Ferric  oxide. 

The  six  univalent  atoms  of  the  HO,  the  characteristic  elements  of 
all  hydrates,  are  thus,  by  two  successive  steps,  split  up  into  water 
and  oxygen.  But  between  the  hydrate  and  oxide  there  obviously 
may  be  another  oxyhydrate,  in  which  only  2HO  is  displaced  by  0", 
and  such  a compound  is  well  known  ; it  is  a variety  of  brown  iron 
ore.  The  other  oxyhydrate,  Fe20.^2H0,  is  also  native  (needle  iron 
ore),  as  well  as  being  the  Ferri  Peroxidum  Hydratiim^  B.  P. 


“ Ferri  Peroxidum  Humidum” Fe'"^  6H0 

A variety  of  brown  iron  ore 0 ' 4H0 

“ Ferri  Peroxidum  Hydratum”  (needle  ore)  . Fe'"2  0"22H0 

Ferric  oxide 


The  moist  ferric  hydrate,  as  already  stated,  when  kept  tor  some 
months,  even  under  water,  loses  the  elements  of  water,  and  is  con- 
verted into  an  oxyhydrate  having  the  formula  Fe^H^Og  (limonite  or 
brown  haematite),  which  is  either  a compound  of  the  above  oxyhy- 
drates  (Fe..04H0)+(Fe.0o2H0) , or  is  a definite  intermediate  oxy- 
hydrate (FeA^HO). 

By  ebullition  with  water  for  seven  or  eight  hours,  ferric  hydrate 
is  decomposed  into  water  and  an  oxyhydrate  having  the  formula 
Fe^H207  (Saint-GMles),  which  is  either  a mixture  of  the  official  oxy- 
Fydrate  (Fe2022H0)  with  ferric  oxide  (Fe203),  or  a definite  inter- 
mediate body  (Fe4052H0).  The  relation  of  these  bodies  to  each 
other  will  be  apparent  from  the  following  Table,  in  which,  for  con- 
venience, the  formulae  of  ferric  hydrate  and  oxide  are  doubled. 


Ferric  hydrate  (B.  P.)  (as  stalactite)  . . . Fe^  12H0 

Kilbride  mineral  (?)  Fe^  OlOHO 

Brown  iron  ore  (Huttenrode  and  Baschau)  . Fe4  028H0 

Old  ferric  hydrate  (limonite) Fe^  O^fiHO 

Ferric  oxyhydrate  (B.  P.)  (gothite)  . . . . Fe4  044H0 

Boiled  ferric  hydrate  (turgite) Fe^  0^^2H0 

Ferric  oxide  (red  haematite) Fe^  Og 


The  English  official  ferric  oxyhydrate  (Fe2022H0),  termed  in  the 
British  Pharmacopoeia  Hydrated  Peroxide  of  Iron,  under  the  as- 
sumption that  it  is  a compound  of  ferric  oxide  and  water  (Fe.^Og, 
H,0),  was  formerly  made  by  mixing  solutions  of  ferrous  sulphate  and 
carbonate  of  sodium  and  exposing  the  resulting  ferrous  carbonate  to 
the  air  until  it  was  nearly  all  converted  into  ferric  oxyhydrate  ; hence 
its  old  name,  still  sometimes  seen  on  old  bottles,  of  Ferri  Carbonas 
and  Ferri  Subcarbonas. 

Ferric  Oxide  (another  process.) 

Thirteenth  Synthetical  Reaction. — Roast  a crystal  or  two 
of  ferrous  sulphate  in  a small  crucible  until  fumes  cease 
to  be  evolved ; the  residue  is  a variety  of  ferric  oxide 
(Fe.^Og)  or  peroxide  of  iron,  known  in  trade  as  red  oxide 
of  iron^  colcothar^  crocus^  rouge  (mineral),  or  Venetian  red 


130 


THE  METALLIC  RADICALS. 


It  has  sometimes  been  used  in  pharmacy  in  mistake  for  the 
official  oxyh3^drates  {vide  12th  Sjmthet.  Reac.),  from  which 
it  differs  not  only  in  composition  but  in  the  important 
respect  of  being  almost  insoluble  in  acids. 

The  Scale  Compounds  of  Iron. 

Fourteenth  Synthetical  Reaction, — Repeat  the  twelfth  re- 
action, introducing  a little  solution  of  citric  or  tartaric 
acid,  or  acid  tartrate  of  potassium,  before  adding  to  the 
alkali  (soda,  potash,  or  ammonia),  and  notice  that  now  no 
precipitation  of  ferric  hydrate  occurs.  This  experiment 
serves  to  illustrate,  not  the  manufacture  of  a scale  com- 
pound, but  the  chemistry  of  the  manufacture.  The  effect 
is  due  to  the  formation  of  double  compounds,  ternied  Am- 
monio-Citrate,  Potassio-Citrate,  Ammonio-Tartrate,  Po- 
tassio-Tartrate,  and  similar  Sodium  compounds  of  Iron, 
which  remain  in  solution  along  with  the  secondary  pro- 
duct— sulphate  of  the  alkali  metal.  Such  ferric  compounds, 
made  with  certain  prescribed  proportions  of  recentl}^  pre- 
jDared  ferric  h3"drate  (from  which  all  alkaline  sulphate  has 
been  washed),  and  the  respective  acids  (tartaric  or  citric) 
or  acid  salts  (acid  tartrate  of  posassium),  etc.,  and  the  so- 
lutions evaporated  to  a syrupy  consistence  and  spread  on 
flat  plates  till  diy,  form  the  scale  preparations  known  as 
Ferri  et  Ammonii  Citras,,  U.  S.  P.,  Ferri  Citras^  U.  S.  P. 
(also  Liquor  Ferri  Citratis,^  U.  S.  P.),  Ferri  et  Ammonii 
Tartras,^  U.  S.  P.,  and  Ferri  Potassio-taidras,,  or  rather, 
Ferrum  Tartaratum,^  B.  P.,  Ferri  et  Fotassii  Tartras^, 
U.  S.  P.  A mixture  of  citrate  of  iron  and  ammonium 
with  citrate  of  stiychnia  yields,  on  evaporation,  Ferri  et 
Strychnine  Gitras,^  IJ.  S.  P.  A mixture  of  ferric  citrate  with 
citrate  of  ammonium  and  citrate  of  quinine  yields,  by 
similar  treatment,  the  well-known  scales  of  Ferri  et  Quinine 
Citras,  B.  P.  and  U.  S.  P. 

Specimens  of  these  substances  ma3^  be  prepared  b3^  at- 
tending to  the  following  details.  It  is  essential,  first,  that 
the  ferric  hydrate  be  thoroughly  washed,  or  an  insoluble 
ox3^sulphate  will  be  formed;  second,  that  the  ferric  hydrate 
be  rapidly  washed,  or  an  insoluble  ferric  ox3diydrate  will 
be  produced;  thirdly,  that  the  whole  operation  be  con- 
ducted quickly,  or  reduction  to  green  ferrous  salt  will 
occur ; and,  fourthl3’,  that  the  solutions  of  the  salts  be  not 
evaporated  at  a higher  temperature  than  that  stated,  or 
decomposition  will  take  place. 


IRON. 


131 


In  the  pharmacopoeial  processes  for  the  three  scale  compounds,  the 
ferric  hydrate  is  in  each  case  freshly  made  from  solution  of  ferric 
sulphate  by  precipitation  with  solution  of  ammonia  : — 

Fe.^3S04  GAmHO  ==  FcgGHO  + 3Am2S04 

Ferric  Hydrate  of  Ferric  Sulphateof 

sulphate.  ammonium.  hydrate.  ammonium. 

the  solution  of  ferric  sulphate  being  made  of  a definite  strength  from 
a known  weight  of  ferrous  sulphate.  The  reason  for  adopting  this 
course  is  that  ferric  hydrate  is  unstable  and  cannot  be  weighed,  be- 
cause it  cannot  be  dried  without  decomposing  and  becoming  insoluble, 
as  explained  under  the  12th  reaction.  This  definite  solution  of  ferric 
sulphate  [Liquor  Ferri  Persulphatis,  B.  P.,  Liquor  Ferri  Tersul- 
phatis,  U.  S.  P.)  is  made  by  adding  six  fluidrachms  of  sulphuric  acid 
to  half  a pint  of  water,  warming,  dissolving  eight  ounces  of  crystals  of 
sulphate  of  iron  in  the  liquid,  pouring  in  nitric  acid  (six  fluidrachms 
or  rather  more)  slightly  diluted  until  the  mixture  turns  from  a black 
to  a reddish  color,  and  ruddy  nitrous  vapors  cease  to  be  produced ; 
the  whole  should  measure  eleven  fluidounces,  being  diluted  or  further 
evaporated,  as  the  case  may  be,  to  this  bulk. 

GFeSO^  + 3H2SO4  -h  2HN03=  3(Fe23S04)  + 2NO  + 4H2O 

Ferri  et  Ammonii  Gitras,  U.  S.  P. — Ferric  hydrate  is  dissolved 
in  solution  of  citric  acid,  ammonia  added,  and  the  whole  evaporated 
to  dryness. 

To  prepare  the  ferric  hydrate,  dilute  eight  fluidounces  of  the  above 
solution  of  ferric  sulphate  with  about  a quart  of  water ; pour  this 
into  two  or  three  pints  of  water  containing  excess  of  solution  of  am- 
monia— about  5 fluidounces  of  “ Strong  Solution  of  Ammonia,”  or 
15  ounces  of  “Solution  of  Ammonia.”  (If  the  opposite  course  were 
adopted,  the  alkaline  liquid  poured  into  the  ferric  solution,  the  pre- 
cipitate would  contain  ferric  oxysulphate,  or  hydrato-sulphate,  which 
interferes  with  the  brilliancy  of  the  scales.)  Thoroughly  stir  the 
mixture  (it  will  smell  strongly  of  ammonia,  if  enough  of  the  latter  has 
been  added),  allow  the  precipitate  to  subside,  pour  away  the  super- 
natant liquid,  add  more  water,  and  repeat  the  washing  until  a little  of 
the  liquid  tested  for  by-product  (sulphate  of  ammonium)  by  solution 
of  chloride  or  nitrate  of  barium  ceases  to  give  a white  precipitate 
(sulphate  of  barium).  Collect  the  ferric  hydrate  on  a filter,  drain, 
and  place,  while  still  moist,  in  a solution  of  four  ounces  of  citric  acid 
in  eight  of  water,  placed  in  an  evaporating  basin,  over  a water-bath, 
stir  frequently,  until  the  whole,  or  nearly  the  whole,  of  the  hydrate 
has  dissolved.  To  the  solution,  when  cold,  add  nearly  two  fluid- 
ounces  of  strongest  (or  five  and  a half  of  weak)  solution  of  ammonia, 
filter,  evaporate  over  a water-bath  to  the  consistence  of  syrup,  spread 
thinly  on  panes  of  glass,  and  dry  (at  a temperature  not  exceeding 
100^  F.).  The  product  scales  off  the  glass  in  deep-red  transparent 
laminae. 

Ferri  et  Quinioe  Gitras,  B.  P.  and  U.  S.  P. — Ferric  hydrate  and 
pure  quinia  are  dissolved  in  solution  of  citric  acid,  ammonia  added, 
and  the  whole  evaporated  to  dryness.  The  product  contains  citrate 
of  iron,  citrate  of  quinia,  and  citrate  of  ammonium. 


132 


THE  METALLIC  RADICALS. 


The  ferric  hydrate  is  obtained  from  four  and  a half  fluidounces  of 
the  solution  of  ferric  sulphate,  with  all  the  precautions  described  in 
the  previous  paragraph,  a proportionate  quantity  of  ammonia  being 
employed. 

AVhile  the  ferric  hydrate  is  being  washed,  prepare  the  quinia  by 
dissolving  one  ounce  of  the  ordinary  sulphate  of  quinia  in  eight 
ounces  of  distilled  water,  acidified  with  sufficient  sulphuric  acid  to 
dissolve  the  sulphate  (about  12  fluidrachms  of  the  official  “ diluted 
sulphuric  acid”),  and  to  the  clear  liquid  add  solution  of  ammonia, 
well  mixing  the  product  by  stirring,  until  the  whole  of  the  quinia  is 
precipitated  (that  is,  until  the  mixture,  after  thorough  agitation, 
smells  of  ammonia).  Collect  the  precipitate  on  a filter,  let  it  drain, 
and  wash  away  adhering  solution  of  sulphate  of  ammonium  by  passing 
through  it  about  a pint  and  a half  of  distilled  water. 

(It  will  be  observed  that  the  principle  involved  in  the  preparation 
of  quinia  from  its  sulphate  is  identical  with  that  which  obtains  in 
the  precipitation  of  alumina,  ferric  hydrate,  or  hydrate  of  zinc,  etc. 
A soluble  sulphate — or,  indeed,  any  common  soluble  salt — has  its 
acidulous  constituent  removed  by  the  superior  affinity  of  the  basylous 
radical  in  ammonia,  or  other  alkali,  an  insoluble  precipitate  and  a 
new  soluble  sulphate  being  formed.  The  latter  is  washed  away, 
leaving  the  former  pure.  In  such  manipulations,  when  economy  has 
to  be  practised,  soda  is  the  alkali  generally  employed.  Ammonia, 
however,  has  the  advantage  of  showing  the  moment  when  its  work 
of  removing  an  .acidulous  radical  is  completed;  for  the  salts  which 
ammonium  forms  with  such  acidulous  radicals  as  SO4,  Cl,  NO3,  and 
C.JI^O.^  are  inodorous,  while  it  itself  has  a powerful  odor;  so  long, 
therefore,  as  the  salt  to  be  decomposed  is  not  wholly  attacked,  the 
addition  of  ammonia  does  not  give  an  ammonia  cal  odor  to  the  mix- 
ture, the  ammonia,  as  such,  being,  in  fact  destroyed ; but  when  the 
work  is  accomplished,  the  quantity  of  ammonia  last  added  remains 
as  ammonia,  and  communicates  its  natural  smell  to  the  liquid.) 

The  ferric  hydrate  and  quinia  being  now  washed  and  drained,  dis- 
solve the  former,  and  afterwards  the  latter,  in  a solution  of  three 
ounces  of  citric  acid  in  five  of  distilled  water,  the  acid  liquid  being 
warmed  over  a water-bath,  and  portions  of  the  precipitates  stirred  in 
as  fast  as  solution  is  effected.  “ Let  the  solution  cool,  then  add  in 
small  quantities  at  a time  twelve  fluidrachms  of  solution  of  ammonia 
diluted  with  two  fluidounces  of  distilled  water,  stirring  the  solution 
briskly,  and  allowing  the  quinia  which  separates  with  each  addition 
of  ammonia  to  dissolve  (in  the  acid)  before  the  next  addition  is 
made.  (Excess  of  ammonia  must  be  avoided  or  the  quinia  will  be 
precipitated.)  Filter  the  solution,  ejapbrate  to  the  consistence  of 
a thin  syrup,  and  then  dry  in  thin  layers  on  flat  porcelain  or  glass 
plates  at  a temperature  of  100^.  Remove  the  dry  salt  in  flakes,  and 
keep  it  in  a stoppered  bottle.”  Long-continued  exposure  to  sun- 
light causes  opacity  in  the  scales,  and  renders  them  difficultly  soluble 
(Wood). 

Ferri  et  Strychnice  Citras,  U.  S.  P.,  is  prepared  by  mixing  a 
solution  containing  five  grains  of  strychnia  and  five  grains  of  citric 
acid  with  a solution  containing  five  hundred  grains  of  citrate  of  iron 


IRON. 


133 


and  ammonium,  evaporating  the  mixture  at  a temperature  not  ex- 
ceeding 140^  to  a syrupy  consistence,  and  scaling  in  the  usual  way 
by  spreading  it  upon  plates  of  glass. 

Ferrum  Tartaratum,  B.  P. ; Ferri  et  Potassii  Tartras,  U.  S.  P. 
— Ferric  hydrate  is  dissolved  in  solution  of  acid  tartrate  of  potassium, 
and  the  whole  evaporated  to  dryness. 

The  ferric  hydrate  obtainable  from  five  and  a half  fluidounces  of 
the  official  solution  of  ferric  sulphate  by  the  action  of  ammonia,  in 
the  manner  detailed  in  the  previous  paragraphs,  is  mixed  (in  a mortar), 
while  still  moist  but  well  drained,  with  two  ounces  of  acid  tartrate  of 
potassium.  The  whole  is  set  aside  for  twenty-four  hours,  with  occa- 
sionally rubbing  to  promote  contact  and  reaction  of  the  molecules 
(otherwise  somewhat  sluggish  in  attacking  each  other),  and  then 
heated  in  a dish  over  a water-bath  to  a temperature  not  exceeding 
1400  F.  • a pint  of  distilled  water  is  then  added,  and  the  mixture 
kept  warm  until  nothing  more  will  dissolve.  Filter,  evaporate  at  a 
temperature  not  exceeding  140^  (greater  heat  causes  decomposition), 
and  when  the  mixture  has  the  consistence  of  syrup,  spread  on  panes 
of  glass  and  dry  (in  any  warm  and  light  place  shown  by  a thermome- 
ter to  be  not  hotter  than  140°).  Pemoye  the  dry  salt  in  flakes,  and 
keep  it  in  well-closed  bottles. 

Ferri  et  Ammonii  Tartras,  U.  S.  P.,  is  made  by  saturating  solu- 
tion of  acid  tartrate  of  ammonium  with  ferric  hydrate,  evaporating, 
and  scaling.  The  acid  tartrate  is  prepared  by  exactly  neutralizing 
half  of  any  quantity  of  tartaric  acid  by  carbonate  of  ammonium,  and 
then  adding  the  other  half. 

The  foregoing  are  the  only  official  scale  preparations  of  iron. 
Many  others  of  similar  character  might  be  formed.  The  Citrate 
dissolves  slowly  in  cold  but  readily  in  warm  water.  None  crystallize 
or  give  other  indications  of  definite  chemical  composition.  Their 
properties  are  only  constant  so  long  as  made  with  unvarying  propor- 
tions of  constituents.  Their  want  of  chemical  compactness,  the  loose 
state  in  which  the  iron  is  combined,  precludes  their  recognition  as 
well-defined  chemical  compounds,  yet  possibly  enables  them  to  be 
more  readily  assimilated  as  medicines  than  some  of  the  more  definite 
ferrous  and  ferric  salts. 

Wine  of  Iron,  or  “Steel”  wine  [Vinum  Ferri,  B.  P.),  made  by 
digesting  iron  wire  in  sherry  wine,  probably  contains  tartrate  of  po- 
tassium and  iron  and  other  iron  salts,  formed  by  action  of  the  metal 
on  the  acid  tartrate  of  potassium  and  tartaric,  citric,  malic,  and  acetic 
acids  present  in  the  wine.  Vinum  Ferri  Gitratis,  B.  P.,  is  a solution 
of  ammonio-citrate  of  iron  in  orange  wine. 

Black  Hydrate  of  Iron.  Ferro-ferric  Hydrate. 

Ferri  Oxidum  Magneticum^  B.  P. 

Fifteenth  Synthetical  Reaction. — To  tivo-thirds  of  a small 
quantity  of  a solution  of  ferrous  sulphate  add  a little  sul- 
phuric acid ; warm,  and  gradually  add  nitric  acid,  as  de- 
scribed in  the  tenth  reaction,  care  being  taken  not  to  allow 
12 


134 


THE  METALLIC  RADICALS. 


one  drop  more  nitric  acid  than  necessary  to  fall  into  the 
test-tube.  Add  the  other  third  of  ferrous  sulphate,  shake, 
and  pour  the  liquid  into  excess  of  an  alkali ; black  (at  first 
brown)  hydrate  of  iron,  or  ferroso-ferric  hydrate  (Fe38HO  = 
re2HO,  Fe^GHO),  is  produced. 

Fe.,3SO,  + FeSO,  + 8NaHO  = Fe38HO  + 4Na^SO, 

Ferric  Ferrous  Soda.  Blk.  hydrate  Sulphate 

sulphate.  sulphate.  of  iron.  of  sodium. 

It  is  so  readily  attracted  by  a magnet,  even  when  moist, 
as  to  collect  round  the  latter  when  immersed  in  the  super- 
natant liquid.  Hence  the  B.  P.  name,  Ferri  Oxidum  Mag- 
neticum. 

In  this  process  the  nitric  acid  oxidizes  the  hydrogen  of  the  sul- 
phuric acid,  the  sulphuric  radical  uniting  with  the  ferrous  sulphate, 
whose  iron  is  at  the  same  time  altered  from  the  ferrous  to  the  ferric 
condition,  ferric  sulphate  being  formed.  If  too  much  nitric  acid  be 
employed,  the  second  portion  of  ferrous  sulphate  will  also  be  converted 
into  ferric  salt,  and  the  solution,  on  the  addition  of  alkali,  yield  only 
red  ferric  hydrate.  This  result  may  be  avoided  by  evaporating  the 
solution  of  ferric  sulphate  nearly  to  dryness,  thus  boiling  off  excess 
of  nitric  acid,  or  by  pouring  first  the  ferric  and  then  the  ferrous  liquid 
into  the  alkali  and  thoroughly  stirring  the  mixture  ; any  nitric,  acid 
is  then  neutralized  and  rendered  incapable  of  oxidizing  the  ferrous 
sulphate  subsequently  added. 

Black  hydrate  of  iron  is  decomposed  by  heat,  yielding,  in  a closed 
vessel,  oxyhydrates,  and,  finally,  black  oxide  of  iron  or  ferroso-ferric 
oxide.  Heated  in  the  air  it  absorbs  oxygen  and  gives  ferric  oxide. 
The  black  forge-scales,  which  collect  near  the  blacksmith’s  anvil, 
have  the  composition  of  ferroso-ferric  oxide  ; the  black  magma  formed 
on  exposing  a mixture  of  iron  and  water  to  the  air  is  ferroso-ferric 
hydrate ; but  these  varieties  are  apt  to  contain  particles  of  metal, 
and,  hence,  give  hydrogen  gas  when  dissolved  in  acids — a character 
which  distinguishes  them  from  the  official  preparation. 

If  a dried  specimen  of  the  black  hydrate  of  iron  be  required,  the 
mixture  should  be  well  boiled  and  then  set  aside  for  an  hour  or  two 
to  favor  aggregation  of  the  particles,  the  mixture  filtered,  and  the 
precipitate  washed  until  the  washings  contain  no  trace  of  sulphate 
(indicated  by  a white  precipitate  with  chloride  of  barium).  Black 
hydrate  of  iron  absorbs  oxygen  even  at  the  temperature  of  the  water- 
bath;  it  should  consequently  be  dried  at  120^,  a temperature  at 
which  only  slight  oxidation  occurs. 

Pernitrate  of  Iron.  Ferric  Nitrate. 

Sixteenth  Synthetical  Reaction, — Place  a few  iron  tacks 
in  dilute  nitric  acid  and  set  aside  ; solution  of  ferric  nitrate, 
or  pernitrate  of  iron,  is  formed  (FeyGNOg). 

Fe.,  + SIINOg  = Fe.GNOg  + 411,0  + 2NO 

Iron.  Xitric  Ferric  Water.  Nitric 

acid.  nitrate.  oxide. 


IRON. 


135 


This  solution,  made  with  care,  and  of  a prescribed  strength,  forms 
the  Liquor  Ferri  Pernitratis,  B.  P.  (sp.  gr.  1.107)  and  U.  S.  P.  (sp. 
gr.  1.065).  The  process  is  as  follows : Four  and  a half  fluidounces  of 
nitric  acid  are  diluted  with  sixteen  ounces  of  distilled  water,  and  one 
ounce  of  iron  wire,  free  from  rust,  dissolved  in  the  mixture,  the  latter 
being  kept  cool  to  avoid  violence  of  action.  The  liquid  is  finally 
filtered  and  diluted  to  thirty  fluidounces. 

Reduced  Iron. 

Seventeenth  Synthetical  Reaction. — Pass  hydrogen  gas 
(dried  by  passing  over  pieces  of  chloride  of  calcium  con- 
tained in  a tube,  or  through  sulphuric  acid  in  a wash 
bottle)  into  a small  quantity  of  ferric  oxyhydrate  or  oxide 
(“  subcarbonate,’’  U.  S.  P.)  contained  in  a tube  arranged 
horizontally  (a  test-tube,  the  bottom  of  which  has  been 
accidentally  broken,  answers  very  well),  the  oxide  being- 
kept  hot  by  a gas-flame ; oxygen  is  removed  from  the 
oxide  by  the  hydrogen,  steam  escapes  at  the  open  end  of 
the  tube,  and  after  a short  time,  when  moisture  ceases  to 
be  evolved,  metallic  iron,  in  a minute  state  of  division, 
remains. 

Fe.Og  + 3H,  = Fe^  + 3H,0 

Ferric  Hydrogen.  Iron.  Water, 
oxide. 

Wliile  still  hot  throw  the  iron  out  into  the  air ; it  takes  Are 
and  falls  to  the  ground  as  oxide. 

If  the  ferric  oxide  is  reduced  in  a gun-barrel  heated  by  a strong 
furnace,  the  particles  of  iron  aggregate  to  some  extent,  and,  when 
cold,  are  only  slowly  oxidized  in  dry  air.  This  latter  form  of  re- 
duced iron  is  Fer  r4duit,  or  Quevennd s Iron,  the  Ferri  pulvis,  or 
Ferrum  Redactum,  B.  P.  and  U.  S.  P. — “ a fine  grayish-black  pow- 
der, strongly  attracted  by  the  magnet,  and  exhibiting  metallic  streaks 
when  rubbed  with  firm  pressure  in  a mortar.”  It  is  often  admin- 
istered in  the  form  of  lozenges  [Trochisci  Ferri  Redacti,  B.P.)  gum 
and  sugar  protecting  the  iron  from  oxidation  as  well  as  forming  a 
vehicle  for  its  administration. 

Note. — The  spontaneous  ignition  of  the  iron  in  the  above  experi- 
ment is  an  illustration  of  the  influence  of  minute  division  on  chemi- 
cal affinity.  The  action Js  the  same  as  occurs  whenever  iron  rusts, 
and  the  heat  evolved  and  amount  of  oxide  formed  is  not  greater 
from  a given  quantity  of  iron  ; but  the  surface  exposed  to  the  action 
of  the  oxygen  of  the  air  is,  in  the  case  of  this  variety  of  reduced 
iron,  so  enormous  compared  with  the  weight  of  the  iron,  that  heat 
cannot  be  conducted  away  sufficiently  fast  to  prevent  elevation  of 
temperature  to  a point  at  which  the  whole  becomes  incandescent. 
In  the  slow  rusting  of  iron,  escape  of  heat  occurs,  but  is  not  ob- 


13G 


THE  METALLIC  RADICALS. 


served,  because  spread  over  a length  of  time ; in  the  spontaneous 
ignition  of  reduced  iron  the  whole  is  evolved  at  one  moment. 


Ferric  Pyrophosphate. 

Eighteenth  Synthetical  Reaction, — To  solution  of  pjH’o- 
phosphate  of  sodium  add  solution  of  persulphate  of  iron  ; 
a 3"ellowisli-wliite  precipitate  of  ferric  p^H’ophospliate  (Fe^ 
3P2O-,  9H2O)  separates.  This  precipitate,  dissolved  in 
solution  of  citrate  of  ammonium,  and  evaporated,  3delds 
apple-green  scales  (Fer7'i  pyrophosphas^  U.  S.  P.,  contain- 
ing fort3-eight  per  cent,  of  anhydrous  p3n'ophosphate). 

(b)  Reactions  Imping  Analytical  Interest  {Tests). 

(The  ironfcccurring  as  a ferrous  salt.) 

First  Analytical  faction, — Pass  sulphuretted  hydrogen 
(H2S)  through  a ^Piition  of  a ferrous  salt  (^.g.,  ferrous 
sulphate)  slightl3^^ftlulated  hy  hydrochloric  acid;  no  pre- 
cipitate occurs. 

This  is  a valuable  negative  fact,  as  will  be  evident  pre- 
sentl3^ 

Second  Analytical  Reaction. — Add  sulph3^drate  of  am- 
monium (NH^HS)  to  solution  of  a ferrous  salt ; a black  pre- 
cipitate of  ferrous  sulphide  (FeS)  falls. 

FeSO,  + 2AmHS  = FeS  -f  Am2SO,  -f  H^S. 

Third  Analytical  Reaction. — Add  solution  of  ferrocwa- 
nide  of  potassium  (yellow  prussiate  of  potash),  K^Fe"C3"j;, 
or  K^Fcy"",  to  solution  of  a ferrous  salt;  a precipitate 
(K^^Ye^^Fcy)  falls,  at  first  white,  but  rapidl3^  becoming  blue, 
owing  to  absorption  of  ox3’gen. 

Fourth  Analytical  Reaction. — To  solution  of  a ferrous 
salt  add  ferridc3^anide  of  potassium  (red  prussiate  of  pot- 
ash), K^Fe'"2C3Y,,  or  K^Fdcy ; a precipitate  (Fe"j.Fdcy) 
resembling  Prussian  blue  (Turnbull’s  blue)  is  thrown  down. 

Other  Analytical  Reactions. — The  precipitates  produced 
from  ferrous  solutions  on  the  addition  of  alkaline  carbo- 
nates, phosphates,  and  arseniates,  as  already  described  in 
the  synthetical  reactions  of  ferrous  salts,  are  characteristic, 
and  hence  have  a certain  amount  of  anal3Tical  interest,  but 
are  inferior  in  this  respect  to  the  four  reactions  above  men- 
tioned. 

Note. — Tlie  alkalies  (solution  of  potash,  soda,  or  ammo- 
nia) are  incomplete  precipitants  of  ferrous  salts,  and  are 


IRON. 


13t 


therefore  almost  useless  as  tests.  To  solution  of  a ferrous 
salt  acid  ammonia  (NH^HO);  on  filtering  and  testing  with 
sulphydrate  of  ammonium,  iron  will  still  be  found  in  the 
solution.  To  another  portion  of  the  ferrous  solution  add 
a few  drops  of  nitric  acid  and  boil  ; this  converts  the  fer- 
rous into  ferric  salt,  and  now  alkalies  will  wholly  remove 
the  iron,  as  already  twice  seen  during  the  performance  of 
the  synthetical  experiments. 

In  actual  analysis,  the  separation  of  iron  as  ferric  hydrate  is  an 
operation  of  frequent  performance.  This  is  always  accomplished  by 
the  addition  of  alkali,  and,  if  the  iron  occurs  as  a ferrous  salt,  by 
previous  ebullition  with  a little  nitric  acid.  Ferrocyanide  and  ferrid- 
cyanide  of  potassium  are  the  tests  used  in  distinguishing  ferrous  from 
ferric  salts. 

(The  iron  occurring  as  a ferric  salt.) 

Sixth  Analytical  Reaction, — Through  a ferric  solution 
(ferric  chloride,  e,  g,)  pass  sulphuretted  hydrogen  ; a white 
precipitate  of  the  sulphur  of  the  sulphuretted  hydrogen 
falls,  and  the  ferric  is  reduced  to  a ferrous  salt,  the  latter 
remaining  in  solution.  This  reaction  is  of  frequent  occur- 
rence in  practical  analj^sis. 

+ 2H,S  = 4FeCl,  + 4HC1  + S,. 

Seventh  Analytical  Reaction, — Add  sulphydrate  of  am- 
monium to  a ferric  solution  ; the  latter  is  reduced  to  the 
ferrous  state,  and  black  ferrous  sulphide  (FeS)  is  precipi- 
tated as  in  the  second  analytical  reaction,  sulphur  being 
set  free. 

Eighth  Analytical  Reaction, — To  a ferric  solution  add 
ferrocyanide  of  potassium  (K^FeCyg,  or  K^Fcy"")  ; a pre- 
cipitate of  Prussian  blue,  the  common  pigment,  occurs 
(Fe"'43Fe"Cyg,  or  Fe'^'^Fcy^^g).  {Ferri  Ferrocyanidum,^ 
U.  S.  P.) 

Ninth  Analytical  Reaction, — To  a ferric  solution  add 
solution  of  ferridcyanide  of  potassium ; no  precipitate 
occurs,  but  the  liquid  is  darkened  to  a greenish  or  olive 
hue,  according  to  the  strength. 

Tenth  Analytical  Reaction. — This  is  the  production  of  a 
red  precipitate  of  ferric  hydrate,  on  the  addition  of  alkalies 
to  ferric  salts,  and  is  identical  with  the  twelfth  synthetical 
reaction. 

Note. — This  reaction  illustrates  the  conventional  character  of  the 
terms  synthesis  and  analysis.  It  is  of  equal  importance  to  the  manu- 

12* 


138 


THE  METALLIC  RADICALS. 


facturer  and  the  analyst,  and  is  synthetical  or  analytical  according 
to  the  intention  with  which  it  is  performed. 

Other  ferric  reactions  have  occasional  analytical  inter- 
est. In  neutral  ferric  solutions  the  tannic  acid  in  aqueous 
infusion  of  galls  occasions  a bluish-black  inky  precipitate, 

the  basis  of  ordinary  writing  ink. (The  Mistura  Ferri 

Aromatica  of  the  British  Pharmacopoeia,  made  by  digesting 
metallic  iron  in  an  infusion  of  various  vegetable  substances, 
contains  tannate,  or  rather  tannates  of  iron  : it  is  commonly 
known  in  Ireland  by  the  name  of  Heberden’s  Ink,  after 
the  physician  by  whom  it  was  first  used.  It  contains  about 

1 grain  of  iron  in  1 pint.)- Sulphocyanide  of  Potassium 

(KCyS)  causes  the  formation  of  ferric  sulphocy^anate, 
which  is  of  deep  blood-red  color.- There  is  no  ferric  car- 

bonate ; alkaline  carbonates  cause  the  precipitation  of  ferric 
hydrate,  while  carbonic  acid  gas  escapes. 

Note. — Cyanogen  (NC,  or  Cy'),  ferrocyanogen  (FeCgNg,  or  FeCy^, 
or  simply  Fey""),  and  ferrideyanogen  (Fe.^Cyi2,  Pdey^^),  are 
radicals  which  play  the  part  of  non-metallic  elements,  just  as  am- 
monium in  its  chemical  relations  resembles  the  metallic  elements. 
They  will  be  again  referred  to. 

Memorandum.— reader  must  on  no  account  omit  to 
write  out  equations  or  diagrams  expressive  of  each  of  the 
reactions  of  iron,  analytical  as  well  synthetical.  It  is  pre- 
sumed that  this  has  already  been  done  immediately  after 
each  reaction  has  been  performed. 


DIRECTIONS  FOR  APPLYING  THE  FOREGOING  ANALYTICAL  REAC- 
TIONS TO  THE  ANALYSIS  OF  AN  AQUEOUS  SOLUTION  OF 
SALTS  CONTAINING  ONE  OF  THE  METALS,  ZiNC,  ALUMI- 
NIUM, Iron. 

Add  solution  of  ammonia  gradually : — 

A dirty^-green  precipitate  indicates  iron  in  the  state  of  a 
ferrous  salt. 

A red  precipitate  indicates  iron  in  the  state  of  a ferric 
salt. 

A white  precipitate,  insoluble  in  excess,  indicates  the 
presence  of  an  aluminium  salt. 

A white  precipitate,  soluble  in  excess,  shows  zinc. 

These  results  may  be  confirmed  by  the  application  of  some  of  the 
otlier  tests  to  fresh  portions  of  the  solutiop. 


ZINC,  ALUMINIUM,  IRON. 


139 


TABLE  OF  SHORT  DIRECTIONS  FOR  APPLYING  THE  FOREGOING 
ANA.LYT1CAL  REACTIONS  TO  THE  ANALYSIS  OF  AN  AQUEOUS 
SOLUTION  OF  SALTS  OF  OISTE,  TWO,  Oil  ALL  THREE  OP  THE 
METALS,  Zinc,  Aluminium,  Iron. 

Boil  about  half  a test-tubeful  of  the  solution  with  a few  drops  of 
nitric  acid.  This  insures  the  conversion  of  ferrous  into  ferric  salts, 
and  enables  the  next  reagent  (ammonia)  completely  to  precipitate 
the  iron.  Add  excess  of  ammonia,  and  shake  the  mixture.  Filter. 


Precipitate 

Filtrate 

A1  Fe.* 

Zn. 

Dissolve  in  HCl,  add  excess  of  KHO, 

Test  by  AmHS. 

stir,  filter. 

(white  ppt.). 

Ppt. 

Filtrate 

Fe 

Al. 

(red  ppt.). 

Neutralize  by  HCl,  and 
add  excess  of  AmHOf 
(white  ppt.). 

Note  I. — If  iron  is  present,  portions  of  the  original  solu- 
tion must  be  tested  by  ferridcyanide  of  potassium  for  ferrous, 
and  by  ferrocyanide  for  ferric  salts  ; dark-blue  precipitates 
with  both  indicate  both  salts. 

Note  II. — If  no  ferrous  salt  is  present,  ebullition  with 
nitric  acid  is  unnecessary.  It  is,  perhaps,  therefore  advi- 
sable always  to  determine  this  point  by  previously  testing 
a little  of  the  original  solution  with  ferridcyanide ; if  no 
blue  precipitate  occurs,  the  nitric  acid  treatment  may  be 
omitted. 

Chart  for  all  Metals  hitherto  considered. 

The  following  Table  {vide  p.  141)  is  perhaps  the  best,  but  not 
the  only  adaptation  of  the  ordinary  reactions  to  systematic  analysis. 
It  is  little  else  than  the  addition  of  the  analytical  scheme  for  the 

* The  aluminium  precipitate  (AlgCHO)  is  white,  the  iron  (Fe^BHO) 
red.  If  the  precipitate  is  red,  iron  must  be  and  aluminium  may  be 
present ; if  white,  iron  is  absent,  and  further  operation  on  the  preci- 
pitate unnecessary. 

t Alumina,  when  in  small  quantity,  is  sometimes  prevented  from 
being  precipitated  by  ammonia  through  the  presence  of  organic  mat- 
ter derived  from  the.  filter  paper  by  action  of  the  potash.  In  cases  of 
doubt,  therefore,  before  adding  ammonia  boil  the  liquid  with  a little 
nitric  acid,  which  destroys  any  organic  matter. 


140 


THE  METALLIC  RADICALS. 


third  group  to  that  of  the  first  two  groups.  As  before,  analysis  is 
commenced  by  the  addition  of  chloride  of  ammonium  (NH^Cl)  to 
prevent  partial  precipitation  of  magnesium,  and  ammonia  (NH^HO) 
to  neutralize  any  acid.  The  latter  would  attack  the  chief  group- 
precipitant,  sulphydrate  of  ammonium  (NH^HS),  preventing  its 
useful  action,  and  causing  a precipitation  of  the  sulphur  it  commonly 
contains. 

Note. — When  a test  gives  no  reaction,  absence  of  the  body  sought 
for  may  be  fairly  inferred.  If  group-tests  (that  is,  tests  which  pre- 
cipitate a group  of  substances)  give  no  reaction,  the  analyst  is 
saved  the  trouble  of  looking  for  either  member  of  the  respective 
groups. 


ZINC,  ALUMINIUM,  IRON. 


Hi 

hi 

<i 

o 

< 

o 

w 

H 

hi 

<1 

cc 

Ph 

O 

O 

S 

P 

P 

o 


p p 

p a 
a - 
< 

<1 
p 

o 


a ^ 


o 

W 

B 

<1 

6 

s 


M 

h 

c3  ^ 


o 
^ a 


c3 

PQ 


o tS 
> ^ 
O h 

S ’-^ 

o 

h ^ 

o O 

.^W 

O C ^ ky( 

't-5  NJ  -r-l 

.-p  ^ s 

.£^3  * ^ 

n- 


Sta 


s 

S o 
= scu 

. s' 
<1 


pH 

Ph  c3 


O g: 

'■’Cp 

offio 

H (-1  _h 


'O  TJ 

CO  Prt 

.2S 

p-1 


p C tif  *-P 
pN  ^ ^ 
^ oO 


o3  a 

-M 

P ^ 

O >73 

<1 


. "o  fM  a 

M.s 

"a  ^ Gi  W sS 

... 

rp  <1^  P 

a-SPS 

I ^cg.SP 

K d 


-h  br^ 

as  I 


^ cTu 
! s ^ 

^ n3 


P-  rP 


m ^ 

S ® p^ 
^ a S ^ 


P^ 


° £*a 

gWy“ 

>% 


141 


Add,  also,  a few  drops  of  HNO3  if  Fe  be  present — i.  e.,  if  the  ppt.  be  black.  {Vide  notes  on  pp.  136  and  139.) 


142 


THE  METALLIC  RADICALS. 


QUESTIONS  AND  EXEECISES. 

207.  Name  the  chief  ores  of  iron. 

208.  How  is  the  metal  obtained  from  the  ores  ? 

209.  What  is  the  chemical  difference  between  cast  iron,  wrought 
iron,  and  steel  ? 

210.  Explain  the  process  of  welding. 

211.  What  is  the  nature  of  chalybeate  waters  ? 

212.  Illustrate  by  formulae  the  difference  between  ferrous  and  fer- 
ric salts. 

213.  Under  what  different  circumstances  may  the  atom  of  iron  be 
considered  to  exert  bivalent,  trivalent,  and  sexivalent  activity  ? 

214.  Write  a paragraph  on  the  nomenclature  of  iron  salts. 

215.  Give  a diagram  of  the  official  process  for  the  preparation  of 
ferrous  sulphate. 

216.  In  what  respects  do  Sulphate  of  Iron,  Granulated  Sulphate 
of  Iron,  and  dried  Sulphate  of  Iron  differ  V 

217.  How  is  ferrous  sulphate  obtained  on  the  large  scale  ? 

218.  Mention  the  chemical  names  of  wffiite,  green,  and  blue  vitriol. 

219.  Why  does  ferrous  sulphate  become  browm  by  prolonged  ex- 
posure to  air  ? 

220.  Give  a diagram  showing  the  formation  of  Ferrous  Carbonate 

221.  Describe  the  action  of  atmospheric  oxygen  on  ferrous  carbon- 
ate : can  the  effect  be  prevented  ? 

222.  In  what  order  would  you  mix  the  ingredients  of  Mistura  \ 
Ferri  Composita,  and  why  ? 

223.  Write  out  an  equation  illustrative  of  the  formation  of  the  ' 
Phosphate  of  Iron. 

224.  Why  is  acetate  of  sodium  used  in  the  preparation  of  ferrous  i 

phosphate  ? I 

225.  Which  four  compounds  of  iron  may  be  formed  by  the  direct 

union  of  their  elements  ? • 

226.  Give  the  official  .method  for  the  preparation  of  Solution  of  j 
Ferric  Chloride. 

227.  Of  what  use  is  the  spirit  in  Tincture  of  Perchloride  of  Iron  ? ! 

228.  How  may  Ferrous  be  converted  into  Ferric  Sulphate  ? j 

229.  What  is  the  formula  of  Ferric  Acetate?  and  how  is  it  pre- 
pared for  use  in  pharmacy  ? j 

230.  Express,  by  formulae,  the  difference  betw^een  Ferri Peroxidum  | 

Humidum,  B.  P.,  and  Ferri  Peroxidum  Hydratum,  B.  P.  I 

231.  How  does  Ferric  Hydrate  act  as  an  antidote  to  arsenic  ? | 

232.  What  are  the  properties  of  anhydrous  ferric  oxide? 

233.  What  are  the  general  characters  and  mode  of  production  of  ! 
the  medicinal  scale  preparations  of  iron? 

234.  In  wdiat  state  is  the  iron  in  Vinum  Ferri,  B.  P.  ? | 

235.  What  other  form  of  AVine  of  Iron  is  official  in  Great  Britain  ? ; 

236.  Give  equations  illustrating  the  chief  steps  in  the  artificial  ( 
production  of  the  so-called  Magnetic  Oxide  of  Iron. 

237.  How  is  precipitated  magnetic  oxide  of  iron  distinguished  from 
the  varieties  made  directly  from  the  metal  ? 


ARSENICUM,  ANTIMONY.  143 

238.  Why  is  magnetic  oxide  of  iron  officially  directed  to  be  dried 
at  a temperature  not  exceeding  120®  Fahr.  ? 

239.  Give  a diagram  showing  the  formation  of  Ferric  Nitrate. 

240.  Work  out  a sum  showing  how  much  anhydrous  ferric  oxide 
will  yield,  theoretically,  one  hundred-weight  of  iron.  Ans.  160  lbs. 

241.  What  are  the  properties  of  anhydrous  ferric  oxide  ? 

242.  Give  the  characteristic  tests  for  iron,  distinguishing  between 
ferrous  and  ferric  reactions,  and  illustrating  each  by  an  equation  or 
a diagram : — 

a.  Sulphydrate  of  ammonium. 

h.  Ferrocyanide  of  potassium. 

c.  Ferridcyanide  of  potassium, 

d.  Caustic  alkalies. 

e.  Sulphocyanate  of  potassium. 

243.  Describe  the  action  of  ammonia  on  salts  of  iron,  aluminium, 
and  zinc  respectively. 

244.  What  precautions  must  be  used  in  testing  for  calcium  in  the 
presence  of  iron  ? 

245.  How  is  magnesium  detected  in  the  presence  of  zinc  ? 

246.  How  is  aluminium  detected  in  the  presence  of  magnesium  ? 

247.  Draw  up  a scheme  for  the  analysis  of  an  aqueous  liquid  con- 
taining salts  of  iron,  barium,  and  potassium. 

248.  How  may  zinc,  magnesium,  and  ammonium  be  consecutively 
removed  from  aqueous  solution  ? 


ARSENICUM,  ANTIMONY. 

These  two  elements  resemble  metals  in  appearance  and  in  the 
character  of  some  of  their  compounds ; but  they  are  still  more  closely 
allied  to  the  non-metals,  especially  to  phosphorus  and  nitrogen 
They  are  quinquivalent  (As^  Sb^),  as  seen  in  arsenic  anhydride 
(AS2O5)  and  pentachloride  of  antimony  (SbCl5),  but  usually  exert 
trivalent  activity  only  ( As^'S  Sb'"^),  as  seen  in  the  hydrogen  and  other 
compounds  (ASH3,  ASCI3,  AsBr3,  Asig).  A few  preparations  of 
these  elements  are  used  in  medicine ; but  all  are  more  or  less  power- 
ful poisons,  and  hence  have  considerable  toxicological  interestf  The 
iodide  {Arsenici  lodidum,  U.  S.  P.)  is  made  by  cautiously  fusing 
together  atomic  proportions  of  arsenicum  and  iodine.  It  is  an  orange- 
red  crystalline  solid  soluble  in  water.  The  Ijk^uot  ATscudci  6t 
Hydrargyri  lodidi,  U.  S.  P.,  is  made  by  dissolving  iodide  of  arseni- 
cum and  red  iodide  of  mercury  in  water,  in  the  proportion  of  1 grain 
of  each  of  the  solids  to  104  grains  of  water. 

Arsenicum  is  an  exception  to  the  rule  that  the  atomic  weights 
(taken  in  grains,  grammes,  or  other  weight)  of  elements,  under 
similar  circumstances  of  temperature  and  pressure,  give  equal  volumes 
of  vapor,  the  equivalent  weight  (75)  of  arsenicum  only  occupying 
halt  such  a volume.  Hence,  while  the  molecular  weights  (that  is, 
double  the  atomic  weights)  of  oxygen  (0^  = 32),  hydrogen  (H,  = 2), 
nitrogen  (N2  28),  etc.,  give  a similar  bulk  of  vapor  at  any  given 


144 


THE  METALLIC  RADICALS. 


temperature  and  pressure,  the  double  atomic  weight  of  arsenicum, 
(As2  = 150),  at  the  same  temperature  and  pressure,  only  affords  half 
this  bulk.  It  would  appear,  therefore,  that  the  molecule  of  arsenicum 
contains  four  atoms,  and  that  its  formula  is  As^.  As  with  sulphur, 
however,  arsenicum,  in  the  state  ordinarily  known  to  us,  may  be  ab- 
normal, and  a variety  yet  be  found  in  which  the  molecular  weight  is 
double  (instead  of  quadruple)  the  atomic  weight. 

From  observed  analogy  between  the  two  metals,  the  molecular 
constitution  of  antimony  is  probably  similar  to  that  of  arsenicum. 


ARSENICUM. 

Symbol  As.  Atomic  weight  75. 

Sources. — Arsenical  ores  are  frequently  met  with  in  nature,  the 
commonest  being  the  arsenio-sulphide  of  iron  (FeSAs).  This  mineral 
is  roasted  in  a current  of  air,  the  oxygen  of  which,  combining  with 
the  arsenicum,  forms  common  white  arsenic  (As.^Og)  {Acidum  Arseni- 
osum,  B.  P.  and  U.  S.  P.)  which  is  condensed  in  chambers  or  long 
flues.  It  commonly  “ occurs  as  a heavy  white  powder,  or  in  sublimed 
masses,  which  usually  present  a stratified  appearance,  caused  by  the 
existence  of  separate  layers,  differing  from  each  other  in  degrees  of 
opacity.”  Realgar  (red  algar)  is  the  red  native  sulphide  (As.^S2), 
and  orpiment  [auripigmentum,  the  golden  pigment)  the  yellow  native 
sulphide  (As^Sg)  of  arsenicum. 

Reactions  having  (a)  Synthetical  and  (6)  Analytical 
Interest. 

(a)  Reactions  having  Synthetical  Interest. 

Alkaline  Solution  of  Arsenic. 

First  Synthetical  Reaction. — Boil  a grain  or  two  of  pow- 
dered arsenic  (AS2O3)  in  water  containing  an  equal  weight 
of  carbonate  of  potassium,  and,  if  necessary,  filter.  The 
solution,  colored  with  compound  tincture  of  lavender,  and 
containing  4 grains  of  arsenic  per  ounce,  forms  the  Liquor 
Arsenicalis.^  B.  P.,  or  Liquor  Potassii  Arsenitis.^  U.  S.  P. 
(FowleFs  Solution.) 

Note. — This  official  solution  does  not  generally  contain  arsenite 
of  potassium ; for  the  arsenic  does  not  decompose  the  carbonate  of 
potassium,  or  only  after  long  boiling.  From  concentrated  solutions 
carbonic  acid  gas  is  more  quickly  eliminated. 

Arsenious  Acids  and  other  Arsenites. 

When  arsenic  (AS2O3)  is  dissolved  in  excess  of  solutions  of  potash 
or  soda,  arsenides  are  formed  having  the  formulae  Kn2As03  and 


ARSENICUM. 


145 


NaH^AsOg.  Boiled  with  excess  of  arsenic,  one  molecule  of  these 
salts  combines  with  one  of  arsenic.  The  usual  character  of  such 
compounds  is  that  of  oily  alkaline  liquids.  Arsenic  or  arsenious 
anhydride  (the  so-called  arsenious  acid),  when  dissolved  in  water, 
yields  true  arsenious  acid  (HgAsOg),  the  arsenite  of  hydrogen. 

-^^2^3  + 3H2O  = 2H3ASO3 

Arsenious  Water.  Arsenious 

anhydride.  acid. 

Acid  Solution  of  Arsenic. 

Second  Synthetical  Reaction, — Boil  arsenic  with  dilute 
hydrochloric  acid.  Such  a solution  made  with  prescribed 
proportions  of  acid  and  water,  and  containing  4 grains  of 
arsenic  (As^Og)  per  ounce,  forms  Liquor  Arsenici  Hydro- 
chlo7'icus,  B.  P.  {Liquor  Arsenici  Ghloridi^  U.  S.  P.)  (De 
Valangin^s  Solution  contained  a grain  and  a half  per  ounce.) 

Note. — No  decomposition  occurs  in  this  experiment.  The  liquid  is 
simply  a solution  of  arseftic  in  dilute  hydrochloric  acid.  These  two 
solutions  may  be  preserved  for  analytical  operations. 

Mem. — The  practical  student  should  boil  arsenic  in  water  also, 
and  thus  have  an  acid,  alkaline,  and  aqueous  solution  for  analytical 
comparison. 


Arsenicum. 

Third  Synthetical  Reaction. — Place  a grain  or  less  of 
arsenic  at  the  bottom  of  a narrow  test-tube,  cover  it  with 
about  half  an  inch  or  an  inch  of  small  fragments  of  dry 
charcoal,  and  hold  the  tube,  nearly  horizontally,  in  aflame, 
the  mouth  being  loosely  covered  by  the  thumb.  At  first 
let  the  bottom  of  the  tube  project  slightly  beyond  the  flame, 
so  that  the  charcoal  may  become  nearly  red-hot ; then  heat 
the  bottom  of  the  tube.  The  arsenic  will  sublime,  become 
deoxidized  by  the  charcoal,  carbonic  oxide  being  formed, 
and  arsenicum  deposited  in  the  cool  part  of  the  tube  as  a 
dark  mirror-like  metallic  incrustation. 

There  is  a characteristic  odor,  resembling  garlic,  emitted  during 
this  operation,  probably  due  to  a partially  oxidized  trace  of  arseni- 
cum which  escapes  from  the  tube  ; for  arsenic  alone  does  not  give 
this  odor ; moreover,  arsenicum  being  a freely  oxidizable  element, 
its  vaporous  particles  could  scarcely  exist  in  the  air  in  an  entirely 
unoxidized  state. 

Metallic  arsenicum  [Arsenicum,  U.  S.  P.)  may  be  obtained  in 
large  quantities  by  the  above  process  if  the  operation  be  conducted 
in  vessels  of  commensurate  size.  But  performed  with  great  care,  in 
narrow  tubes,  using  not  charcoal  alone,  but  hlackflux  (a  mixture  of 
charcoal  and  carbonate  of  potassium  obtained  by  heating  acid  tar- 


146 


THE  METALLIC  RADICALS. 


trate  of  potassium  in  a test-tube  or  other  closed  vessel  till  no  more 
fumes  are  evolved),  the  reaction  has  considerable  analytical  interest, 
the  garlic  odor  and  the  formation  of  the  mirror-like  ring  being  highly 
characteristic  of  arsenicum.  Compounds  of  mercury  and  antimony, 
however,  give  sublimates  which  may  be  mistaken  for  arsenicum. 

Arsenic  Acid  and  other  Arseniates. 

Fourth  Synthetical  Reaction, — Boil  a grain  or  two  of 
arsenic  with  a few  drops  of  nitric  acid  until  red  fumes  cease 
to  be  evolved ; evaporate  the  solution  in  a small  dish  to 
dryness,  to  remove  excess  of  nitric  acid ; dissolve  the 
residue  in  water;  the  product  is  Arsen'ic  acid  (HgAsO^). 

Arsenic  acid,  when  strongly  heated,  loses  the  elements  of  water, 
and  arsenic  anhydride  remains  (As.^05). 

Arsenic  anhydride  readily  absorbs  water  and  becomes  arsenic  acid 
(H3ASO4).  Arsenic  acid  is  readily  reduced  to  arsenious  by  the 
action  of  reducing  agents  such  as  sulphurous  acid,  H3ASO4-I-H2SO3 
=H3As03+H2S0,. 

Salts  analogous  to  arsenic  acid,  the  arseniate  of  hydrogen,  are 
termed  arseniates,  and  have  the  general  formula  R'3  AsO^.  The  am- 
monium arseniate  (Am.^HAsO^)  may  be  made  by  neutralizing  arsenic 
acid  with  ammonia.  Its  solution  in  water  forms  a useful  reagent. 

Arsenic  acid  is  used  as  an  oxidizing  agent  in  the  manufacture 

of  the  well-known  dye,  magenta. 

Arsenite  and  arseniate  of  sodium  are  used  in  the  cleansing  opera- 
tions of  the  calico-printer. 

Pyroarseniate  and  Arseniate  of  Sodium. 

Fifth  Synthetical  Reaction, — Fuse  a minute  fragment 
of  common  white  arsenic  (As^^Og)  with  nitrate  of  sodium 
(NaNOg)  and  dried  carbonate  of  sodium  (Na.^C03)  in  a 
porcelain  crucible,  and  dissolve  the  mass  in  water;  solution 
of  arseniate  of  sodium  (Na^HAsOJ  results. 

As.Og  + 2NaN03  + Na.^COg  = Ka^As.O^  + N^Og  + CO, 

Arsenic.  Nitrate  of  Carbonate  Pyroarseniate  Nitrous  Carbonic. 

sodium.  of  sodium.  of  sodium.  anhydride,  acid  gas. 

The  official  proportions  (B.  P)  are  10  of  arsenic  to  8|  of  nitrate 
of  sodium  and  5|  of  dried  carbonate,  each  powdered,  the  whole  well 
mixed,  fused  in  a crucible  at  a red  heat  till  effervescence  ceases,  and 
the  liquid  poured  out  on  a slab.  The  product  is  pyroarseniate  of 
sodium  (NagAs.,0.).  Dissolved  in  water,  crystallized,  and  dried,  the 
salt  has  the  formula  Na.2HAs04,  7H2O  {Sodii  Arse7iias,  U.  S.  P.). 

Na^As^O,  + ISH^O  = 2(Na2lIAs04,  111,0). 

Heated  to  300^  F.  the  crystals  lose  all  water.  A solution  of  4 
grains  of  the  anhydrous  salt  (Na.^lIAsO^)  in  1 ounce  of  water  forms 
the  Liquor  Sodii  Arseniatis,  U.  S.  P.  The  anhydrous  salt  is  used 


ARSENICUM. 


14T 

in  this  preparation  because  the  crystallized  is  of  somewhat  uncertain 
composition.  The  fresh  crystals  are  represented  by  the  formula 
Na.TIAsO^,  I2H2O  (=  53.7  per  cent  of  water) ; these  soon  effloresce 
and  yield  a stable  salt  having  the  formula  Na^^HAsO^,  7H2O  (= 
40.4  per  cent,  of  water).  To  avoid  the  possible  employment  of  a 
mixture  of  these  bodies,  the  invariable  anhydrous  salt  is  officially 
used,  constancy  in  the  strength  of  a powerful  preparation  being 
thereby  secured. 

The  student  will  find  useful  practice  in  verifying  the  above  numbers 
representing  the  centesimal  proportion  of  water  in  the  two  arseniates 
of  sodium.  This  will  readily  be  accomplished  if  what  has  already 
been  stated  respecting  a symbol  representing  a number  as  well  as  a 
name,  and  the  remarks  concerning  molecular  weight,  be  remembered. 

The  shape  of  each  of  the  two  varieties  of  ars'eniate  of  sodium 
(Na2HAs04,  I2H2O,  and  Na2HAs04,  7H2O)  is  identical  with  that 
of  the  corresponding  phosphate  of  sodium  (Na2HP04,  I2H2O,  and 
Na2HP04,  7H2O) ; the  structure  of  the  molecule  of  the  12-arseniate 
is  the  same  as  that  of  12-phosphate,  and  the  7-arseniate  as  that  of 
the  7-phosphate  ; the  two  former  are  isomorphous,  the  two  latter  are 
isomorphous.  This  is  only  one  instance  of  the  strong  analogy  of 
arsenicum  and  its  compounds  with  phosphorus  and  its  corresponding 
compounds.  The  preparation  and  characters  of  the  next  substance, 
arseniate  of  iron,  will  remind  the  learner  of  phosphate  of  iron. 

Arseniate  of  Iron.  Ferrous  Arseniate. 

Sixth  Synthetical  Reaction. — To  solution  of  arseniate  of 
sodium  add  a little  acetate  of  sodium  and  then  solution  of 
ferrous  sulphate,  a precipitate  of  ferrous  arseniate  occurs 
(Fe32As04)  {Ferri  Arsenias.^  B.  P.).  On  the  large  scale  4 
parts  of  dried  arseniate  and  3 of  acetate  dissolved  in  40 
of  water,  mixed  with  9 of  sulphate  in  60  of  water,  may 
be  employ^ed.  The  precipitate  should  be  collected  on  .a 
calico  filter,  washed,  squeezed,  and  dried  at  a low  tem- 
perature (100°  F.)  over  a wash-bath  to  avoid  excessive 
oxidation. 

2Na,HAsO,  + 2NaC2[l302  + 3FeSO, 

Arseniate  of  Acetate  of  Ferrous 

sodium.  sodium.  sulphate. 

3Na,SO,  + 2HC,H,0,. 

Sulphate  of  Acetic  acid, 

sodium. 

The  use  of  the  acetate  of  sodium  is  to  insure  the  occurrence  of 
acetic  acid  in  solution,  where  otherwise  would  be  free  sulphuric 
acid.  Sulphuric  acid  is  a solvent  of  ferrous  arseniate  ; acetic  acid  is 
not.  It  is  impossible  to  prevent  the  separation  of  sulphuric  acid,  if 
only  ferrous  sulphate  and  arseniate  of  sodium  be  employed.  At  the 
instant  of  precipitation  ferrous  arseniate  is  white,  but  rapidly  becomes 
of  a green  or  greenish-blue  color,  owing  to  absorption  of  oxygen  and 
formation  of  a ferroso-ferric  arseniate.  It  is  a tasteless  amorphous 
powder,  soluble  in  acids. 


= Fe32AsO^  + 

Ferrous 

arseniate. 


148 


THE  METALLIC  RADICALS. 


The  Hydride  and  SuliMdes  of  Arsenicum^  and  the 
Arsenites  and  Arseniates  of  Copper  and  of  Silver  are  men- 
tioned in  the  following  analytical  paragraphs  : — 

(b)  Reactions  having  Analytical  Interest  ( Tests). 

First  Analytical  Reaction. — Cut  or  break  off  portions  of 
the  tube  containing  the  sublimate  of  arsenicum  obtained  in 
the  third  synthetical  reaction,  put  them  into  a test-tube 
and  heat  the  bottom  of  the  latter,  holding  it  nearly  hori- 
zontally, and  partially  covering  the  mouth  with  the  finger 
or  thumb;  the  arsenicum  (AsJ  will  absorb  oxygen  from 
the  air  in  the  tube,  and  the  resulting  arsenious  anhydride 
(AS2O3)  be  deposited  on  the  cool  part  of  the  tube  in  char- 
acteristic octahedral  (oxt'w,  okto^  eight ; iSpa,  hedra.^  side) 
crystals,  more  or  less  perfect. 

Microscopic  Test. — Prove  that  the  crystals  are  identical 
in  form  with  those  of  common  white  arsenic,  by  heating  a 
grain  or  less  of  the  latter  in  another  test-tube,  examining 
the  two  sublimates  by  a good  lens  or  compound  microscope. 

Notes. — The  production  of  arsenicum  and  its  subsequent  oxidation 
are  test-reactions  perhaps  not  quite  so  delicate  as  some  that  follow, 
requiring  more  material  for  their  satisfactory  performance ; yet  the 
form  of  the  crystals  is  charateristic,  no  other  volatile  body  being 
likely  to  be  mistaken  for  them ; and  in  toxicological  cases  it  is 
desirable  to  obtain  the  arsenicum  in  a similar  state  to  that  in  which 
probably  it  originally  exerted  its  effects ; the  processes  alluded  to 
are  therefore  of  considerable  importance.  Moreover,  arsenicum, 
ready  for  sublimation  to  crystalline  arsenic,  is  easily  obtained  from 
solution  by  the  following  reaction  : — 

Second  Analytical  Reaction.— Vlace  a thin  piece  of  cop- 
per, about  a quarter  inch  wide  and  half  inch  long,  in  a 
solution  of  arsenic,  acidified  by  hydrochloric  acid,  and  boil 
(nitric  acid  must  not  be  present,  or  the  copper  itself  will 
be  dissolved) ; arsenicum  is  deposited  on  the  plate  in  a 
metallic  condition,  an  equivalent  portion  of  copper  going 
into  solution.  Pour  off  the  supernatant  liquid  from  the 
copper,  wash  the  latter  once  or  twice  with  water,  dry  the 
piece  of  metal  by  holding  in  the  fingers  and  passing  through 
a flame,  and  finally  place  it  at  the  bottom  of  a clean  dry 
narrow  test-tube  ; sublime  as  described  in  the  last  reaction, 
again  noticing  the  form  of  the  resulting  crystals. 

This  is  commonly  known  as  Reinsclfs  test  for  arsenicum.  The 
tube  may  be  reserved  for  subsequent  comparison  with  an  antimonial 
sublimate  (p.  100). 


ARSENICUM. 


149 


Note. — Copper  itself  frequently  contains  arsenicum,  a fact  that 
may  not,  perhaps,  much  trouble  an  operator  so  long  as  he  is  perform- 
ing experiments  in  practical  chemistry  merely  for  educational  pur- 
poses ; but  when  he  engages  in  the  analysis  of  bodies  of  unknown 
composition,  he  must  assure  himself  that  neither  his  apparatus  nor 
materials  already  contain  the  element  of  which  he  is  in  search. 

The  detection  of  arsenicum^  in  metallic  copper  is  best  accom- 
plished by  distilling  a mixture  of  a few  grains  of  the  sample  with 
five  or  six  times  its  weight  of  ferric  hydrate  or  chloride  (free  from 
arsenicum)  and  excess  of  hydrochloric  acid.  The  arsenicum  is  thus 
volatilized  in  the  form  of  chloride  of  arsenicum,  and  may  be  condensed 
in  water  and  detected  by  sulphuretted  hydrogen  (5th  Analytical 
Keaction)  or  Reinsch’s  test.  The  ferric  chloride  solution  is,  if  neces- 
sary, freed  from  any  trace  of  arsenicum  by  evaporating  once  or  twice 
to  dryness  with  excess  of  hydrochloric  acid  (Odling). 

Third  Analytical  Reaction  — MarsNs  test.  — Generate 
hydrogen  in  the  usual  way  from  water  by  zinc  and  sul- 
phuric acid,  a bottle  of  about  four  or  six  ounces  capacity 
being  used,  and  a funnel-tube  and  short  delivery-tube 
passing  through  the  cork  in  the  usual  manner  (described 
on  page  81).  Diy  the  escaping  hydrogen  (except  in  rough 
experiments,  when  it  is  unnecessary)  by  adapting  to  the 
delivery-tube,  by  a pierced  cork,  a short  piece  of  wider 
tubing  containing  fragments  of  chloride  of  calcium.  To 
the  opposite  end  of  the  drying-tube  fit  a piece  of  narrow 
tubing  ten  or  twelve  inches  long,  made  of  hard  German 
glass,  and  having  its  aperture  narrowed  by  drawing  out 
in  the  flame  of  the  blowpipe.  When  the  hydrogen  has 
been  escaping  at  such  a rate  and  for  a sufficient  number 
of  minutes  as  to  warrant  the  operator  in  concluding  that 
all  the  air  originally  existing  in  the  bottle  has  been  ex- 
pelled, set  light  to  the  jet,  and  then  pour  eight  or  ten  drops 
of  the  aqueous  solution  of  arsenic,  or  three  or  four  drops 
of  the  acid  or  alkaline  solution  of  arsenic,  previously  pre- 
pared, into  the  funnel-tube,  washing  the  liquid  into  the 
generating-bottle  with  a little  water.  The  arsenic  is  at 
once  reduced  to  the  state  of  arsenicum,  and  the  latter 
combines  wdth  some  of  the  hydrogen  to  form  hydride  of 
arsenicum  or  arseniuretted  ly^drogen  gas  (AsHg).  Imme- 
diately hold  a piece  of  earthenware  or  porcelain  (the  lid 
of  a porcelain  crucible,  if  at  hand)  in  the  hydrogen  jet  at 
the  extremity  of  the  delivery-tube ; a brown  spot  of  con- 
densed arsenicum  is  deposited.  Collect  several  of  these 
spots,  and  retain  them  for  future  comparison  with  antimo- 
nial  spots  (p.  160). 


13* 


150 


THE  METALLIC  RADICALS. 


The  separation  of  arsenicum  in  the  flame  is  due  to  the  decomposi- 
tion of  the  arseniuretted  hydrogen  by  the  heat  of  combustion.  The 
cool  porcelain  at  once  condenses  the  arsenicum,  and  thus  prevents 
its  oxidation  to  white  arsenic,  which  would  otherwise  take  place  at 
the  outer  edge  of  the  flame. 

Hold  a small  beaker  or  wide  test-tube  over  the  flame 
for  a few  minutes ; a white  film  of  arsenic  (As.^Og)  will  be 
slowly  deposited,  and  may  be  further  examined  in  contrast 
with  a similar  antimonial  film  (p.  160). 

During  these  experiments  the  effect  produced  by  the  arsenical 
vapors  on  the  color  of  the  hydrogen-flame  will  have  been  noticed ; 
they  give  it  a dull  livid  bluish  tint.  This  is  characteristic. 

Apply  the  flame  of  a gas-lamp  to  the  middle  of  the  hard 
delivery-tube  ; the  arseniuretted  hydrogen,  as  before,  is 
decomposed  by  the  heat,  but  the  liberated  arsenicum  (As^) 
immediately  condenses  in  the  cool  part  of  the  tube  beyond 
the  flame,  forming  a dark  metallic  mirror.  The  tube  may 
be  removed  and  kept  for  comparison  with  an  antimonial 
deposit. 

Note  I. — Zinc,  like  copper,  frequently  itself  contains  arsenicum. 
When  a specimen  free  from  arsenicum  is  met  with,  it  should  be  re- 
served for  analytical  experiments,  or  a quantity  of  guaranteed  purity 
should  be  purchased  of  the  chemical-apparatus  maker.  Sulphuric 
acid  is  more  easily  obtained  free  from  arsenic. 

Note  II. — In  delicate  and  important  applications  of  Marsh’s  test, 
magnesium  may  be  substituted  for  zinc  with  safety,  as  arsenicum 
has  not  yet  been,  nor  is  it  likely  to  be,  found  in  magnesium.  Mag- 
nesium in  rods  is  convenient  for  this  purpose,  and  may  be  obtained 
from  most  dealers  in  chemicals. 

Note  III. — Arseniuretted  hydrogen  is  decomposed  by  strong  sul- 
phuric acid ; hence  chloride  of  calcium  is  used  in  drying  the  gas. 

Fou7ih  Analytical  Reaction  — Fleitniann'^ s test. — Gene- 
rate hj^drogen  by  heating  to  near  the  boiliag-point  a strong 
solution  of  caustic  soda  or  potash  and  some  pieces  of  zinc. 
Drop  into  the  test-tube  a little  arsenical  solution,  and 
spread  over  the  mouth  of  the  tube  a cap  of  filter-paper 
moistened  with  one  drop  of  solution  of  nitrate  of  silver. 
Again  heat  the  tube,  taking  care  that  the  liquid  itself  shall 
not  spirt  up  on  to  the  cap ; the  arsenic  is  reduced  to  ar- 
senicum, the  latter  uniting  with  the  hydrogen  as  in  Marsh’s 
test ; and  the  arseniuretted  hydrogen  passing  up  through 
the  cap  reacts  on  the  nitrate  of  silver,  causing  the  produc- 
tion of  a purplish-black  spot. 

AsIIg  -f  311,0  -f  GAgNOg  = IlgAsOg  + GIINOg  -f  3Ag,. 


ARSENICUM. 


151 


Note. — This  reaction  is  particularly  valuable,  enabling'  the  ana- 
lyst to  quickly  distinguish  arsenicum  in  the  presence  of  its  sister 
element  antimony,  which,  although  it  combines  with  the  hydrogen 
evolved  from  dilute  acid  and  zinc,  does  not  combine  with  the  hydro- 
gen evolved  from  solution  of  alkali  and  zinc,  and  therefore  does  not 
give  the  effect  just  described. 

Fifth  Analytical  Reaction. — To  a solution  of  chloride  of 
tin  in  strong  hydrochloric  acid  add  a very  small  quantity^ 
of  any  arsenical  solution.  Arsenicum  then  separates,  espe- 
cially on  the  application  of  heat,  giving  the  mixture  a yel- 
lowish and  then  brownish  hue  or  grayish-brown  turbidity^, 
or  even  a sediment  of  gray-brown  flocks,  according  to  the 
amount  present.  Much  water  prevents  the  reaction ; its 
presence,  therefore,  must  be  avoided  as  much  as  possible  ; 
indeed  a liquid  saturated  by  hydrochloric  acid  gas  gives  best 
results.  Arsenic  in  sulphuric  or  hydrochloric  acids  or  in 
tartar  emetic,  etc.,  may^  be  detected  by  this  method.  Ni- 
trates, such  as  subnitrate  of  bismuth,  must  first  be  heated 
with  sulphuric  acid  to  remove  the  nitric  radical  before  ap- 
plying this  reduction  test  for  arsenicum.  The  stannous  is 
converted  to  stannic  salt  during  the  reaction. 


Distinction  between  Arsenious  and  Arsenic  combinations. — 
The  above  tests  are  those  of  arsenicum,  whether  existing  in  the  arse- 
nious or  arsenic  condition,  though  from  the  latter  the  element  is  not 
generally  eliminated  so  quickly  as  from  the  former.  Of  the  following 
reactions,  that  with  nitrate  of  silver  at  once  distinguishes  arsenious 
acid  and  other  arsenites  from  arsenic  acid  and  other  arseniates.' 

Mem. — The  exact  nature  of  all  these  analytical  reactions  will  be 
more  fully  evident  if  traced  out  by  diagrams  or  equations. 


Sixth  Analytical  Reaction. — Through  an  acidified  solu- 
tion of  arsenic  pass  sulphuretted  hydrogen  ; a yellow  pre- 
cipitate of  sulphide  of  arsenicum  or  arsenious  sulphide 
(AS2S3)  quickly  falls.  Add  an  alkaline  hydrate  or  sulphy- 
drate  to  a portion  of  the  precipitate;  it  readily  dissolves. 
The  precipitate  consequently’’  would  not  be  obtained  on 
passing  sulphuretted  hydrogen  through  an  alkaline  solu- 
tion of  arsenic.  To  another  portion  of  the  precepitate, 
well  drained,  add  strong  hydrochloric  acid  ; it  is  insoluble, 
unlike  sulphide  of  antimony. 

Note  I. — The  only  other  metal  which  gives  a yellow  sulphide  in 
an  acid  solution  by  action  of  sulphuretted  hydrogen  is  cadmium ; 
but  this  sulphide  is  insoluble  in  alkaline  liquids. 


152 


THE  METALLIC  RADICALS 


Note  II. — A trace  of  sulphide  of  arsenicum  is  sometimes  met  with 
in  sulphur  (distilled  from  arsenical  pyrites).  It  may  be  detected  by 
digesting  the  sulphur  in  solution  of  ammonia,  filtering,  and  evapo- 
rating to  dryness ; a yellow  residue  of  sulphide  of  arsenicum  is  ob- 
tained if  that  substance  be  present. 

Seventh  Analytical  Reaction, — Through  an  acidified  solu- 
tion of  arsenic  acid,  or  any  other  arseniate,  pass  sulphu- 
retted hydrogen  ; a yellow  precipitate  of  arsenic  sulphide 
(As.^S-)  slowly  falls.  This  also  is  soluble  in  alkaline  hy- 
drates and  sulphydrates. 

Chemical  Analogy  of  Sulphur  and  Oxygen. — The  solubility  of 
arsenious  and  arsenic  sulphide  in  alkaline  solutions  is  good  evidence 
of  the  close  chemical  analogy  between  them  and  the  corresponding 
oxygen  compounds  of  arsenicum.  The  potassium  arsenite  and  sulph- 
arsenite,  arseniate  and  sulph-arseniate,  have  the  composition  repre- 
sented by  the  following  formulae : — 


K3ASO3 

K3ASS3 


K3ASO4 
KjAsS, ; 


and  the  corresponding  ammonium  and  sodium  salts  have  a similar 
composition : — 

GAmllS  -h  As.^S3  = 2Am3AsS3  -j-  SH.^S 
6AmHS  -f  AS2S-  = 2Am3AsS4  4-  3H.^S. 

Eighth  Analytical  Reaction, — To  an  aqueous  solution  of 
arsenic  add  two  or  three  drops  of  solution  of  sulphate  of 
copper,  and  then  cautiously  add  diluted  solution  of  ammo- 
nia, drop  by  drop,  until  a green  precipitate  is  obtained. 
The  production  of  this  precipitate  is  characteristic  of  ar- 
senicum. To  a portion  of  the  mixture  add  an  acid ; the 
precipitate  dissolves.  To  another  portion  add  alkali ; the 
precipitate  dissolves.  These  two  experiments  show  the 
advantage  of  testing  a suspected  arsenical  solution  by^  lit- 
mus paper  before  applying  this  reaction  ; if  acid,  cautiously 
adding  alkali,  if  alkaline,  adding  acid,  till  neutrality^  is 
obtained.  (Or  a special  copper  reagent  may^  be  used  ; see 
a note  to  the  Eleventh  Analytical  Reaction,  p.  153.) 

The  precipitate  is  arsenite  of  copper  (Cu"HAs03)  or  Scheele's 
Green,  More  or  less  pure,  or  mixed  with  acetate  or,  occasionally, 
carbonate  of  copper,  it  is  very  largely  used  as  a pigment  under  many 
names,  such  as  Brunswick  Green  and  Schweinfurth  (jreen,by  painters, 
paper-stainers,  and  others. 

Ninth  Analytical  Reaction, — Apply  the  test  just  de- 
scribed to  a solution  of  arsenic  acid  or  other  arseniate; 
a somewhat  similar  precipitate  of  arseniate  of  copper  is 
obtained. 


ARSENICUM. 


153 


Tenth  Analytical  Reaction, — Repeat  the  eighth  reaction, 
substituting  nitrate  of  silver  for  sulphate  of  copper  : in 
this  case  yellow  arsenite  of  silver  (AggAsO^)  falls,  also 
soluble  in  acids  and  alkalies. 

Eleventh  Analytical  Reaction, — Apply  the  test  to  a solu- 
tion of  arsenic  acid  or  other  arseniate ; a c7ioco?a^e-colored 
precipitate  of  arseniate  of  silver  (AggAsOJ  falls. 

Copper  and  Silver  Reagents  for  Arsenicum, — The  last  four  reac- 
tions may  be  performed  with  increased  delicacy  and  certainty  of 
result,  if  the  copper  and  silver  reagents  be  previously  prepared  in 
the  following  manner ; To  solution  of  pure  sulphate  of  copper  (about 
1 part  in  20  of  water)  add  ammonia  until  the  blue  precipitate  at 
first  formed  is  nearly,  but  not  quite,  redissolved;  filter  and  preserve 
the  liquid  as  an  arsenicum  reagent,  labelling  it  solution  of  ammonio- 
sidphate  of ‘copper  (B.  P.).  Treat  solution  of  nitrate  of  silver  (about 
1 part  in  40)  in  the  same  way,  and  label  it  solution  of  ammonio- 
nitrate  of  silver  (B.  P.).  The  composition  of  these  two  salts  will 
be  referred  to  subsequently. 

Arsenious  and  Arsenic  Compounds. — While  many  reagents  may 
be  used  for  the  detection  of  arsenicum,  only  nitrate  of  silver,  as 
already  stated,  will  readily  indicate  in  which  state  of  oxidation  the 
arsenicum  exists ; for  the  two  sulphides  and  the  two  copper  precipi- 
tates, though  differing  in  composition,  resemble  each  other  in  appear- 
ance, whereas  the  two  silver  precipitates  differ  in  color  as  well  as  in 
composition. 

Soluble  arseniates  also  give  insoluble  arseniates  with  barium,  cal- 
cium, zinc,  and  some  other  metallic  solutions. 

Antidote, — In  cases  of  poisoning  by  arsenic  or  arsenical 
preparations,  the  most  effective  antidote  is  recently  pre- 
cipitated moist  ferric  hydrate  {Ferri Peroxidum  Humidum^ 
B,  P.,  Ferri  Oxidum  Hydratum,,  U.  S.  P.).  It  is  perhaps 
best  administered  in  the  form  of  a mixture  of  solution  of 
perchloride  of  iron  {Liquor  or  Tinctura)  with  carbonate  of 
sodium — two  or  three  ounces  of  the  former  to  about  one 
ounce  of  the  crystals  of  the  latter.  Instead  of  the  carbon- 
ate of  sodium,  about  a quarter  of  an  ounce  of  calcined  mag- 
nesia may  be  used.  These  quantities  will  render  at  least  10 
grains  of  arsenic  insoluble.  Emetics  should  also  be  given, 
and  the  stomach-pump  applied  as  quickly  as  possible. 

The  above  statements  regarding  the  antidote  for  arsenic  may  be 
verified  by  mixing  the  various  substances  together,  filtering,  and 
proving  the  absence  of  arsenicum  in  the  filtrate  by  applying  some  of 
the  foregoing  tests. 

Mode  of  Action  of  the  Antidote. — The  action  of  the  carbonate  of 
sodium  or  the  magnesia  is  to  precipitate  ferric  hydrate  (Fe^hHO) — 
chloride  of  sodium  (NaCl)  or  magnesium  (MgOl2)  being  formed, 


154 


THE  METALLIC  RADICALS. 


which  are  harmless,  if  not  beneficial,  under  the  circumstances.  The 
reaction  between  the  ferric  hydrate  and  the  arsenic  results  in  the 
formation  of  insoluble  ferrous  arseniate. 

2(Fe,6HO)  + As,0,  = Fe32AsO,  + -H  Fe2HO 

Ferric  Arsenic.  Ferrous  Water.  Ferrous, 

hydrate.  arseniate.  hydrate. 

As  already  stated,  dried  ferric  hydrate  (then  become  an  oxyhy- 
drate,  Fe^0^4H0)  Ferri  Peroxidum  Hydratum,  B.  P.)  has  no 
action  on  arsenic.  Even  the  moist  recently  prepared  hydrate 
(Fe.^GHO)  ceases  to  react  with  arsenic  as  soon  as  it  has  become  con- 
verted into  an  oxyhydrate  (Fe^036H0),  a change  which  occurs 
though  the  hydrate  be  kept  under  water  (Procter).  According  to 
T.  and  H.  Smith  this  decomposition  occurs  gradually,  but  in  an  in- 
creasing ratio ; so  that  after  four  months  the  power  of  the  moist  mass 
is  reduced  to  one-half,  and  after  five  months  to  one-fourth. 


QUESTIONS  AND  EXERCISES. 

249.  "What  is  the  formula  of  a molecule  of  arsenicum? 

250.  In  what  form  does  arsenicum  occur  in  nature? 

251.  Describe  the  characters  of  white  arsenic. 

252.  Name  the  official  preparations  of  arsenicum. 

253.  What  proportion  of  arsenic  (AS2O3)  is  contained  in  Liquor 
Arsenicalis,  B.  P.,  and  Liquor  Arsenici  Hydrochloricus,  B.  P.  ? 

254.  By  what  method  may  arsenic  be  reduced  to  arsenicum  ? 

255.  Give  the  formulae  of  arsenious  and  arsenic  acids  and  anhy- 
drides. 

256.  Explain,  by  diagrams,  the  reactions  which  occur  in  convert- 
ing arsenic  into  Arseniate  of  Sodium  by  the  process  of  the  British 
Pharmacopoeia. 

257.  Why  is  anhydrous  instead  of  crystallized  arseniate  of  sodium 
employed  in  the  preparation  of  Liquor  Sodce  Arseniatis,  B.  P.? 

258.  In  the  preparation  of  Arseniate  of  Iron  from  ferrous  sulphate 
and  arseniate  of  sodium,  why  is  acetate  of  sodium  included  ? 

259.  Describe  the  manipulations  necessary  in  distinguishing  arsenic 
by  its  crystalline  form. 

260.  How  is  Reinsch’s  test  for  arsenicum  applied,  and  under  what 
circumstances  may  its  indications  be  fallacious  ? 

261.  Give  the  details  of  Marsh’s  test  for  arsenicum,  and  the  pre- 
cautions to  be  observed  in  its  performance.  Explain  the  reactions 
by  diagrams. 

262.  What  peculiar  value  has  Fleitmann’s  test  for  arsenicum? 

263.  Describe  the  conditions  under  wdiich  sulphuretted  hydrogen 
becomes  a trustworthy  test  for  arsenicum. 

264.  IIow  may  a trace  of  sulphide  of  arsenicum  be  detected  in 
sulphur  ? 

265.  How  are  the  salts  of  copper  and  silver  applied  as  reagents 
for  the  detection  of  arsenicum  ? 

266.  How  are  arsenites  distinguished  from  arseniates? 


ANTIMONY. 


155 


267.  Mention  the  best  antidote  in  cases  of  poisoning  by  arsenic, 
explain  the  process  by  which  it  may  be  most  quickly  prepared,  and 
describe  its  action. 

268.  What  light  does  the  action  of  arsenic  on  ferric  hydrate  throw 
on  the  constitution  of  the  latter  substance  ? 


ANTIMONY. 

Symbol  Sb  (stibium).  Atomic  weight  122. 

Source  and  Uses, — Antimony  occurs  in  nature  chiefly  as  sulphide, 
Sb2S3.  The  crude  or  hlack  antimony  of  pharmacy  is  this  native 
sulphide  freed  from  earthy  impurities  by  fusion : it  has  a striated, 
crystalline,  lustrous  fracture ; subsequently  powdered  it  forms  the 
grayish-black  crystalline  Antimonium  nigrum,  B.  P.,  Antimonii 
sulphuretum,  U.  S.  P.  The  metal  is  easily  obtained  from  the  sul- 
phide by  roasting,  and  then  reducing  with  charcoal  and  carbonate 
of  sodium.  Metallic  antimony  is  an  important  constituent  of  Type- 
metal,  Britannia  metal  (tea  and  coflee  pots,  spoons,  etc.),  and  the 
best  varieties  of  Pevjter.  The  old  pocula  emetica,  or  everlasting 
emetic  cups,  were  made  of  antimony ; wine  kept  in  them  for  a day 
or  two  acquired  a variable  amount  of  emetic  quality.  The  metal  is 
not  used  in  making  the  antimonial  preparations  of  the  Pharmaco- 
poeia, the  sulphide  alone  being,  directly  or  indirectly,  employed  for 
this  purpose. 

Antimony  has  very  close  chemical  analogies  with  arsenicum.  Its 
atom,  in  the  official  salts,  exerts  trivalent  activity  (e.  g.,  SbClg),  but 
sometimes  it  is  quinquivalent  (e.  g.,  SbClg). 

Reactions  having  (a)  Synthetical  and  (5)  Analytical 
Interest. 

{a)  Reactions  having  Synthetical  Interest. 

Chloride  of  Antimony.  Antimonious  Chloride. 

First  Synthetical  Reaction Boil  half  an  ounce  or  less 

of  sulphide  of  antimony  with  four  or  live  times  its  weight 
of  hydrochloric  acid  in  a dish  in  a fume-chamber  or  the 
open  air;  sulphuretted  hydrogen  is  evolved  and  solution  of 
cliloride  of  antimony,  SbCl^,  obtained. 

Sb.,S3  4-  6HC1  = SSbCl^  + 3H,S 

Sulphide  of  Hydrochloric  Chloride  of  Sulphuretted 

antimony.  acid.  antimony.  hydrogen. 

This  solution,  cleared  by  subsidence,  is  what  is  commonly  known 
as  Butter  of  antimony  [Liquor  Antimonii  Chloridi,  B.  P.).  If 
pure  sulphide  has  been  used  in  its  preparation  the  liquid  is  nearly 
colorless ; but  much  of  that  met  with  in  veterinary  pharmacy  is 
simply  a by-product  in  the  generation  of  sulphuretted  hydrogen  from 


156 


THE  METALLIC  RADICALS. 


native  sulphide  of  antimony  and  hydrochloric  acid,  and  is  more  or 
less  brown  from  the  presence  of  chloride  of  iron.  It  not  unfrequently 
darkens  in  color  on  keeping ; this  is  due  to  absorption  of  oxygen 
from  the  air  and  conversion  of  light-colored  ferrous  into  dark-brown 
ferric  chloride  or  oxychloride. 

True  butter  of  antimony  (SbCl,)  is  obtained  on  evaporating  the 
above  solution  to  a low  bulk,  and  distilling  the  residue.  The  butter 
condenses  (as  a white  crystalline  semi-transparent  mass  in  the  neck  of 
the  retort ; at  the  close  of  the  operation  it  may  be  easily  melted  and 
run  down  in  a bottle,  which  should  be  subsequently  well  stoppered. 

Pentacliloride  of  antimony  (SbClg),  or  antimonic  chloride,  is  a 
fuming  liquid,  obtained  on  passing  chlorine  over  the  lower  chloride. 

Oxychloride  of  Antimony.  Antimonious  Oxychloride. 

Second  Synthetical  Reaction. — Pour  the  solution  of  chlo- 
ride of  antimony  produced  in  the  last  reaction  into  several 
ounces  of  water ; a white  precipitate  of  oxychloride  of  an- 
timony (2SbCl3,  bSh^^Og)  falls,  some  chloride  of  antimony 
remaining  in  the  supernatant  acid  liquid. 

This  is  the  o\^  pulvis  Algarothi,  pidvis  angelicus,  or  mercurius 
vitae.  On  standing  under  water  it  gradually  becomes  crystalline. 

12SbCl3  + 15H,0  = 2SbCl3,5Sb,03  + 30HCI 

Chloride  of  Water.  Oxychloride  of  Hydrochloric 

antimony.  antimony.  acid. 


Oxide  of  Antimony.  Antimonious  Oxide. 

Well  wash  the  precipitate  with  water,  by  decantation 
{vide  p.  93),  and  add  solution  of  carbonate  of  sodium;  the 
♦ chloride  remaining  with  the  oxide  is  thus  decomposed,  and 
oxide  of  antimony  (Sb.^Og)  alone  remains.  This  is  Anti- 
monii  Oxidum.^  B.  P.  and  U.  S.  P.  It  is  of  a light  bulf  or 
grayish-white  color,  or  quite  white  if  absolutely  free  from 
iron,  insoluble  in  water,  soluble  in  hydrochloric  acid,  fusi- 
ble at  a low  red  heat.  The  moist  oxide  of  antimony  may 
be  well  washed  and  employed  for  the  next  reaction,  or  dried 
over  a water-bath.  At  temperatures  above  212°  oxygen  is 
absorbed,  and  other  oxides  of  antimony  formed.  The  pre- 
sence of  the  latter  is  detected  on  boiling  the  powder  in 
solution  of  acid  tartrate  of  potassium,  in  which  oxide  of 
antimony  (Sb^Og)  is  soluble,  but  antimonic  anhydride 
(Sb^O.)  and  the  double  oxide  or  so-called  antimonious  an- 
hydride (Sb^Og)  insoluble.  t 

2SbCl3,5Sb,03  + SNa^COg  = -f  GNaCl  + SCO, 

Oxychloride  of  Carbouate  Oxide  of  Chloride  Carbonic 

^antimony.  of  sodium.  antimony.  of  sodium.  acid  gas. 


ANTIMONY. 


15t 


The  higher  oxide  of  antimony  (Sb205),  termed  antimonic  oxide 
or  anhydride,  corresponding  with  arsenic  anhydride,  is  obtained  on 
decomposing  the  pentachloride  by  water,  or  on  boiling  metallic  anti- 
mony with  nitric  acid.  The  variety  obtained  from  the  chloride  differs 
in  saturating-power  from  that  obtained  from  the  metal,  and  is  termed 
metantimonic  acid  meta,  beyond.) 

Tartar  Emetic. 

Third  Synthetical  Reaction — Mix  the  moist  oxide  of 
antimony  obtained  in  the  previous  reaction  with  about  an 
equal  quantity  of  cream  of  tartar  (6  of  the  latter  to  5 of 
the  dry  oxide)  and  sufficient  water  to  form  a paste ; set 
aside  for  a day  to  facilitate  complete  combination  ; boil 
the  product  with  water,  and  filter;  the  resulting  liquid 
contains  the  double  tartrate  of  antimony  and  potassium 
(KSbC^H^Oy),  potassio-tartrate  of  antimony,  tartrated  an- 
timony, or  tartar  emetic  (emetic,  from  emeo^  I vomit ; 
tartar  from  Taprapo^,  tartaros^  see  Index). 

2KHC,H,Og  + SbA  = 2KSbC,H,0,  + H^O 

Acid  tartrate  Oxide  of  Tartar  emetic.  Water, 

of  potassium.  antimony. 

On  evaporation  the  salt  is  obtained  in  colorless  trans- 
parent triangular-faced  crystals  of  the  above  composition, 
with  a molecule  of  water  of  crystallization,  forming  the 
Antimonium  Tartaratum^  B.  P.  (KSbC^H^O.,  H2O)  the 
Antimonii  et  Potassii  Tartras^  U.  S.  P. 

The  formula  for  tartar  emetic  is  apparently  inconsistent 
with  the  general  formula  for  tartrates  R'R'C^H^Og);  this 
will  be  subsequently  fully  explained  in  connection  with 
Tartaric  Acid.  The  salt  appears  to  be  an  oxytartrate 
(KSbC,H,OgO). 

Tartar  emetic  is  soluble  in  water,  and  slightly  so  in  proof 
spirit.  Dissolved  in  sherry  wine  it  forms  the  official  Vinum 
Antimoniale^  B.  P.,  and  Vinum  Antimonii^  U.  S.  P.  It 
may  be  externally  applied  as  an  ointment,  Unguentum  An- 
timonii Tartarati^  B.  P.  ( Unguentum  Antimonii^  U.  S.  P.). 

Sulphurated  Antimony.  Oxysulphide  of  Antimony. 

Fourth  Synthetical  Reaction, — Boil  a few  grains  of  sul- 
phide of  antimony  with  solution  of  soda  (potash,  U.  S.  P.) 
in  a test-tube  (or  larger  quantities  in  larger  vessels,  10 
ounces  of  sulphide  to  4^  pints  of  the  official  solution  of 
soda  for  2 hours,  frequently  stirring,  and  occasionally  re- 
placing water  lost  by  evaporation),  and  filter;  into  the 
14 


158 


THE  METALLIC  RADICALS. 


filtrate,  before  cool,  stir  diluted  sulphuric  acid  until  the 
liquid  is  slightly  acid  to  test-paper;  a brownish-red  pre- 
cipitate of  oxysulphide  of  antimony,  the  Antimonmm  Sul- 
phuratum^  B.  P.  and  U.  S.  P.,  falls ; filter,  wash,  and  dry 
over  a water-bath.  It  is  a mixture  of  sulphide  of  anti- 
mony (Sb^Sg)  with  a small  and  variable  amount  of  oxide 
(Sb.^Og).  The  oxide  results  from  the  double  decomposition 
of  sulphide  of  antimony  and  soda. 

Antimonii  Oxy sulphur etum. — The  United  States  Phar- 
macopoeia in  another  preparation  orders  carbonate  of 
sodium  instead  of  the  caustic  alkali,  and  directs  that  only 
that  precipitate  be  retained  which  separates  from  the  alka- 
line liquid  on  cooling. 

If  a small  quantity  of  sulphur  be  boiled  with  the  sulphide 
of  antimony  in  solution  of  soda,  the  precipitate  on  the 
addition  of  sulphuric  acid  will  be  bright  orange-red,  on 
account  of  the  presence  of  a higher  sulphide  having  a 
yellow  color  (Sb^S^). 

There  are  some  of  the  many  varieties  of  mineral  Tcerines,  so  called 
from  their  similarity  in  color  to  the  insect  kermes.  Kermes  is  the 
name,  now  obsolete,  of  the  Coccus  llicis,  a sort  of  cochineal-insect, 
fall  of  reddish  juice,  and  used  for  dyeing  from  the  earliest  times. 

Explanation  of  process. — The  sulphides  and  oxides  of  antimony,  • 
like  those  of  arsenicum,  react  with  the  sulphides  and  oxides  of  cer- 
tain metals  to  form  soluble  salts  (Na^SbSg  and  Na^SbOg). 

2Sb,S3  + 6NaHO  = 2Na3SbS3  -+-  Sb.O^  + 3H,0 

Sulphide  of  Soda.  Sulph-antimonite  Oxide  of  Water. 

antimony.  of  sodium.  antimony. 

Sb,,0,  + 6NaH0  = 2Na3Sb03  + SH.^O 

Oxide  of  Soda.  Antimonite  Water, 

antimony.  of  sodium. 

In  the  hot  solutions  of  these  salts  sulphide  and  oxide  of  antimony 
arc  soluble,  and  are  reprecipitated  in  an  indefinite  state  of  combina- 
tion, partially,  on  cooling,  or  wholly  on  the  addition  of  acid.  The 
acid  also  decomposes  the  oxysalt  with  precipitation  of  oxide,  and  the 
sulphur-salt  with  precipitation  of  orange  sulphide  of  antimony.  The 
acid  is  added  to  the  liquid  before  much  oxysulphide  has  deposited 
(that  is,  before  the  solution  is  cool),  in  order  to  insure  uniformity  of 
product. 

2Na3SbS3  4-  SH^SO^  = 3Na,SO,  + Sb.Sg  + 3H,S 

Sulph-autimonite  Sulphuric  Sulphate  of  Sulphide  of  Sulphuretted 

of  sodium.  acid.  sodium.  antimony.  hydrogen. 

2Na3Sb03  + 3H2SO4  = 3NajSOi  + Sb^Oj  + 3H3O 

Antimonite  Sulphuric  Sulphate  Oxide  of  Water. 

of  sodium.  acid.  of  sodium.  antimony. 

The  oxide  and  sulphide  mentioned  in  these  equations,  together  with 
excess  of  sulphide  of  antimony  originally  dissolved  by  the  alkaline 


ANTIMONY. 


159 


liquid,  are  all  precipitated  when  the  acid  is  added,  and  form  the  Sul- 
phurated Antimony  of  the  Pharmacopoeia,  ‘‘  an  orange-red  powder, 
readily  dissolved  by  caustic  soda,  also  by  hydrochloric  acid  with  the 
evolution  of  sulphuretted  hydrogen  and  the  separation  of  a little  sul- 
phur.” Its  antimony  is  detected  by  dissolving  the  precipitate  in 
hydrochloric  acid,  or  in  solution  of  acid  tartrate  of  potassium,  and 
passing  sulphuretted  hydrogen  through  the  liquid,  as  described  in 
the  first  analytical  reaction. 


These  four  synthetical  reactions  illustrate  the  official  processes  for 
the  respective  substances.  The  solution  of  chloride  of  antimony 
is  only  used  in  the  preparation  of  oxide ; the  oxide,  besides  its  use 
in  the  preparation  of  tartar  emetic,  is  mixed  with  twice  its  weight 
of  phosphate  of  calcium  (purified  bone-earth)  to  form  Pulvis  Anti- 
monialis,  B.  P. 

The  sulphides  and  hydride  of  antimony  are  incidentally  men- 
tioned in  the  following  analytical  paragraphs. 

(6)  Reactions  having  Analytical  Interest  {Tests). 

First  Analytical  Reaction. — Through  an  acidified  anti- 
monial  solution  pass  sulphuretted  hydrogen;  an  orange 
precipitate  of  amorphous  sulphide  of  antimony  falls.  It 
has  the  same  composition  as  the  crystalline  black  sulphide 
(Sb.^S3),  into  which,  indeed,  it  is  quickly  converted  by  heat. 
Like  sulphide  of  arsenicum,  it  is  soluble  in  alkaline  solu- 
tions. Collect  a portion  on  a filter  and,  when  well  drained, 
add  hydrochloric  acid ; it  dissolves — unlike  sulphide 

of  arsenicum. 

A higher  sulphide  of  antimony  (Sb^S^)  corresponding  to 
the  higher  sulphide  of  arsenicum,  exists.  It  is  formed  on 
passing  sulphuretted  hydrogen  through  an  acidified  solution 
of  the  higher  chloride  (SbCL),  or  on  boiling  black  sulphide 
of  antimony  and  sulphur  with  an  alkali,  and  decomposing 
the  resulting  filtered  liquid  by  an  acid. 

Note. — The  arsenious  and  antimonious  compounds  only  are  em- 
ployed in  medicine.  The  arseniates  and  antimoniates  are  sometimes 
useful  in  analysis,  and  the  antimonic  chloride  in  chemical  research. 
The  higher  compounds  of  both  elements  are  noticed  here  chiefly  to 
draw  attention  to  the  close  analogy  existing  between  arsenicum  and 
antimony,  an  analogy  carried  out  in  the  numerous  other  compounds 
of  these  elements. 

Second  Analytical  Reaction. — Dilute  two  or  three  drops 
of  the  solution  of  chloride  of  antimony  with  water ; a pre- 
cipitate of  oxychloride  occurs,  the  formation  of  which  has 


160 


THE  METALLIC  RADICALS. 


been  explained  under  the  similar  synthetical  reaction.  The 
occurrence  of  this  precipitate  distinguishes  antimony  from- 
arsenicum,  but  is  a reaction  that  cannot  be  fully  relied 
upon  in  analysis,  because  requiring  the  presence  of  too 
much  material  and  the  observance  of  too  many  conditions. 
Add  a sufficient  quantity  of  hydrochloric  acid  to  dissolve 
the  precipitate,  and  boil  a piece  of  copper  in  the  solution 
as  directed  in  the  corresponding  test  for  arsenicum  {vide 
page  148)  ; antimony  is  deposited  on  the  copper.  Wash, 
dry,  and  heat  the  copper  in  a test-tube  as  before ; the  anti- 
moii}^,  like  the  arsenicum,  is  volatilized  off  the  copper  and 
condenses  on  the  side  of  the  tube  as  white  oxide,  but  the 
sublimate,  from  its  low  degree  of  volatility,  condenses  close 
to  the  copper,  and,  moreover,  is  destitute  of  crystalline 
character,  is  amorphous  (a,  a,  without  ; morphe^ 

shape). 

Shake  out  the  copper  and  boil  water  in  the  tube  for 
several  minutes.  Do  the  same  with  the  arsenical  subli- 
mate similarly  obtained.  The  deposit  of  arsenic  slowly 
dissolves,  and  may  be  recognized  in  the  solution  by 
ammonio-nitrate  of  silver;  the  antimonial  sublimate  is 
insoluble. 

Third  Analytical  Reaction, — Perform  the  experiments 
described  under  Marsh’s  test  for  arsenicum  (pp.  149,  150), 
carefully  observing  all  the  details  there  mentioned,  but 
using  a few  drops  of  solution  of  chloride  of  antimony  or 
tartar  emetic  instead  of  the  arsenical  solution.  Anti- 
moniuretted  hydrogen,  or  hydride  of  antimony  (SbHg),  is 
formed  and  decomposed  in  the  same  way  as  arseninretted 
hydrogen. 

To  one  of  the  arsenicum  spots  on  the  porcelain  lid  (p. 
149)  add  a drop  of  solution  of  “chloride  of  lime”  (bleach- 
ing-powder) ; it  quickly  dissolves.  Do  the  same  with  an 
antimony  spot ; it  is  unaffected. 

Heat  more  quickly  causes  the  volatilization  of  an  arsenicum  than 
an  antimony  spot ; sulphydrate  of  ammonium  more  readily  dissolves 
the  antimony  than  the  arsenicum. 

Boil  water  for  several  minutes  in  the  beaker  or  wide  * 
test-tube  containing  the  arsenious  sublimate  (page  150)  ; 
it  slowly  dissolves  and  may  be  recognized  in  the  solution 
by  the  yellow  precipitate  given  on  the  addition  of  solution 
of  ammonio-nitrate  of  silver.  The  antimonial  sublimate, 
similarly^  treated,  gives  no  corresponding  reaction. 


ANTIMONY. 


IGl 


Pass  a slow  current  of  sulphuretted  hydrogen  through 
""the  delivery-tube  removed  from  the  hydrogen-apparatus 
(page  150),  and,  when  the  air  may  be  considered  to  have 
been  ejxpelled  from  the  tube,  gently  heat  that  portion  con- 
taining the  deposit  of  arsenicum  ; the  latter  will  be  con- 
verted into  a yellow  sublimate  of  sulphide  of  arsenicum. 
Remove  the  tube  from  the  sulphuretted-hj^drogen  appa- 
ratus, and  repeat  the  experiment  with  a similar  antimony 
deposit;  it  is  converted  into  orange  sulphide  of  antimony, 
which,  moreover,  owing  to  inferior  volatility,  condenses 
nearer  to  the  flame  than  sulphide  of  arsenicum. 

Pass  dry  hydrochloric  acid  gas  through  the  two  de- 
livery-tubes.  This  is  accomplished  by  adapting  first  one 
tube  and  then  the  other  by  a cork  to  the  test-tube  contain- 
ing a few  lumps  of  common  salt,  on  which  a little  sulphuric 
acid  is  poured  during  the  momentary  removal  of  the  cork. 
The  sulphide  of  antimony  dissolves  and  disappears;  the 
sulphide  of  arsenicum  is  unaffected. 

Thorough  perception  of  the  chemistry  of  arsenicum  and  anti- 
mony  will  he  obtained  on  constructing  equations  or  diagrams 
descriptive  of  each  of  the  foregoing  reactions. 

Antidote — The  introduction  of  poisonous  doses  of  anti- 
monials  into  the  stomach  is  fortunately  quickly  followed 
by  vomiting.  If  vomiting  has  not  occurred,  or  apparently 
to  an  insufficient  extent,  any  form  of  tannic  acid  may  be 
administered  (infusion  of  tea,  nutgalls,  cinchona,  oak-bark, 
or  other  astringent  solutions  or  tinctures),  an  insoluble 
tannate  of  antimony  being  formed,  and  absorption  of  the 
poison  consequently  somewhat  retarded.  The  stomach- 
pump  must  be  as  quickly  as  possible  applied. 

Recently  precipitated  moist  ferric  hydrate  is  also,  ac- 
cording to  T.  and  H.  Smith,  a perfect  absorbent  of  anti- 
mony from  its  solutions,  the  chemical  actions  being  probably, 
they  say,  similar  to  that  which  takes  place  between  ferric 
hydrate  and  arsenious  anhydride.  It  may  be  given  in  the 
form  of  a mixture  of  perchloride  of  iron  with  either  carbo- 
nate of  sodium  or  magnesia. 

These  statements  may  be  verified  by  mixing  together  the  various 
substances,  filtering,  and  testing  the  filtrate  for  antimony  in  the 
usual  manner. 


14* 


162 


THE  METALLIC  RADICALS. 


DIRECTIONS  FOR  APPLYING  THE  FOREGOING  REACTIONS  TO 
THE  ANALYSIS  OF  AN  AQUEOUS  SOLUTION  OF  SALTS  OF  ONE 
OF  THE  ELEMENTS  ArSENICUM  AND  ANTIMONY. 

Acidify  the  liquid  with  hydrochloric  acid,  and  pass 
through  it  sulphuretted  hydrogen: — 

A yellow  precipitate  indicates  arsenicum. 

An  orange  precipitate  indicates  antimony. 

The  result  may  be  confirmed  by  the  application  of  other 
tests. 


DIRECTIONS  FOR  APPLYING  THE  FOREGOING  REACTIONS  TO 

THE  ANALYSIS  OF  AN  AQUEOUS  SOLUTION  OF  SALTS  OF  BOTH 

Arsenicum  and  Antimony. 

Acidify  a small  portion  of  the  liquid  with  hydrochloric 
acid,  and  pass  througli  it  sulphuretted  hydrogen. 

Note  I.  If  the  precipitate  by  sulphuretted  hydrogen  is  unmis- 
takably orange,  antimony  may  be  put  down  as  present,  and  arseni- 
cum only  further  sought  by  the  application  of  Fleitmann’s  test  to 
the  solution  of  the  sulphides  in  aqua  regia*  freed  from  sulphur  by 
boiling,  or,  better,  to  the  original  solution. 

Note  II.  Sulphide  of  antimony  is  far  less  readily  soluble  than  sul- 
* phide  of  arsenicum  in  solution  of  carbonate  of  ammonium.  But  this 
fact  possesses  limited  analytical  value  ; for  the  color  of  the  sulphides 
is  already  sufficient  to  distinguish  the  one  from  the  other  when  they 
are  unmixed ; and  when  mixed,  much  sulphide  of  antimony  will  pre- 
vent a little  sulphide  of  arsenicum  from  being  dissolved  by  the  alka- 
line carbonate,  while  much  sulphide  of  arsenicum  will  carry  a little 
sulphide  of  antimony  into  the  solution.  When  the  proportions  are, 
apparently,  from  the  color  of  the  precipitate,  less  wide,  solution  of 
carbonate  of  ammonium  will  be  found  useful  in  roughly  separating 
the  one  sulphide  from  the  other.  On  filtering  and  neutralizing  the 
alkaline  solution  by  an  acid,  the  yellow  sulphide  of  arsenicum  is 
reprecipitated.  The  orange  sulphide  of  antimony  will  remain  on  the 
filter. 

Note  III.  Solution  of  bisulphite  of  potassium  is  said  by  Wohler  to 
be  a good  reagent  for  separating  the  sulphides  of  arsenicum  and 
antimony,  the  former  being  soluble,  the  latter  insoluble  in  the  liquid. 

Note  IV.  Another  reagent  for  separating  the  sulphides  of  arse- 
nicum and  antimony  is  strong  hydrochloric  acid.  As  little  water  as 
possible  must  be  present.  On  boiling,  the  sulphide  of  antimony  dis- 
solves, while  the  sulphide  of  arsenicum  remains  insoluble.  The  liquid 

* Aqua  regia  is  a mixture  of  two  parts  hydrochloric  and  one  part 
nitric  acid.  It  was  so  called,  from  its  property  of  dissolving  gold,  the 
“ king”  of  metals. 


ARSENICUM  AND  ANTIMONY. 


163 


slightly  diluted,  filtered,  more  water  added,  and  sulphuretted  hydro- 
gen again  transmitted,  gives  orange  sulphide  of  antimony.  The  pro- 
cess should  previously  be  tried  on  the  precipitated  mixed  sulphides. 
The  presence  of  arsenicum  may  be  confirmed  by  the  application  of 
Fleitmann’s  test  to  the  original  solution. 

Note  Y.  If  the  precipitate  by  sulphuretted  hydrogen  is  unmis- 
takably yellow,  arsenicum  may  be  put  down  as  present,  and  any 
antimony  detected  by  the  previous  or  one  of  the  following  two  pro- 
cesses. These  two  processes  are  rather  long,  and  require  much 
care  in  their  performance,  but  are  useful,  because  a small  quantity 
of  antimony  in  much  arsenicum,  or  vice  versa,  may  be  detected  by 
their  means. 

First  Process, — Generate  hydrogen  and  pass  it  through 
a small  wash-bottle  containing  solution  of  acetate  of  lead, 
to  free  the  gas  from  any  trace  of  sulphuretted  hydrogen  it 
may  possess,  and  then  through  a dilute  solution  of  nitrate 
of  silver  contained  in  a test-tube.  When  the  apparatus  is 
in  good  working  order,  pour  into  the  generating-bottle  the 
solution  to  be  examined,  adding  it  gradually  to  prevent 
violent  action.  After  the  gas  has  been  passing  for  five  or 
ten  minutes,  examine  the  contents  of  the  nitrate-of-silver 
tube  ; arsenicum,  if  present,  will  be  found  in  the  solution 
in  the  state  of  arsenious  acid, 

AsUg  -|-  -j-  GAg^Og  = IlgAsOg  -h  GIINOg  “h  3 Ag2  5 

while  antimony,  if  present,  will  be  found  in  the  black 
precipitate  that  has  fallen,  according  to  the  following 
equation : — 

SbHg  -f  3AgN03  = SbAg2  + 3HNO3. 

The  arsenious  radical  may  be  detected  in  the  clear,  filtered, 
supernatant  liquid,  which  still  contains  much  nitrate  of 
silver,  by  cautiously  neutralizing  with  a very  dilute  solution 
of  ammonia,  or  by  adding  a few  drops  of  solution  of  ammo- 
nio-nitrate  of  silver,  yellow  arsenite  of'  silver  being  pro- 
duced. The  antimony  may  be  detected  by  washing  the 
black  precipitate,  boiling  it  in  an  open  dish  with  solution 
of  tartaric  acid,  filtering,  acidulating  with  hydrochloric 
acid,  and  passing  sulphuretted  hydrogen  through  the  solu- 
tion— the  orange  sulphide  of  antimony  being  precipitated 
(Hofmann). 

Second  process, — Obtain  the  metallic  deposit  in  the  mid- 
dle of  the  delivery-tube  as  already  described  under  Marslds 
test.  Act  on  the  deposit  by  sulphuretted  hydrogen  gas, 
and  then  by  hydrochloric  acid  gas  as  detailed  in  the  third 


ICA  THE  METALLIC  RADICALS. 

analytical  reaction  of  antimony  (p.  160).  If  both  arseni- 
cnm  and  antimony  are  present,  the  deposit,  after  the  action 
of  sulphuretted  hydrogen,  will  be  found  to  be  of  two 
colors,  the  yellow  sulphide  of  arsenicum  being  usually 
further  removed  from  the  heated  portion  of  the  tube  than 
the  orange  sulphide  of  antimony.  Moreover,  subsequent 
action  of  hydrochloric  acid  gas  causes  disa'ppearance  of 
the  antimonial  deposit,  which  is  converted  into  chloride  of 
antimony  and  carried  off  in  the  stream  of  gas. 

The  chief  objection  to  this  process  is  the  liability  of  the  operator 
mistaking  sulphur,  deposited  from  the  sulphuretted  hydrogen  gas  by 
heat,  for  sulphide  of  arsenicum.  But  the  presence  or  absence  of 
arsenicum  is  easily  confirmed  by  applying  Fleitmann’s  test  to  the 
original  solution,  while  the  process  is  most  useful  for  the  detection 
of  a small  quantity  t)f  salt  of  antimony  when  mixed  with  much  arse- 
nical compounds. 


The  laboratory  student  may  now  proceed  to  the  analysis  of  aqueous 
solutions  of  salts  of  any  of  the  metallic  elements  hitherto  considered. 
The  method  followed  may  be  that  for  the  separation  of  the  previous 
three  groups,  sulphuretted  hydrogen  being  first  passed  through  the 
solution  to  throw  out  arsenicum  and  antimony.  The  whole  scheme 
of  analysis  is  given  on  the  next  page.  Three  or  four  solutions  should 
be  examined  fcfore  proceeding  to  the  last  group  of  metals. 

Learners  w'ho  have  no  opportunity  of  working  at  practical  analysis 
will  gain  much  knowledge  by  endeavoring  not  to  remember,  but  to 
understand  these  methods  of  separating  elements  from  each  other  in 
a solution  containing  several  compounds. 


165 


AUSENICUM  AND  ANTIMONY. 


* It  is  not  usually  necessary  to  add  NH^Cl,  the  HCl  with  some  of  the  NH^HO  commonly  giving  sufficient  NH^Cl. 
t Much  time  may  sometimes  be  saved  by  carefully  remembering  the  color  of  the  various  hydrates  and  sulphides 
precipitated.  Thus,  if  the  AmHS  precipitate  is  white,  iron  cannot  be  present,  and  AniHO,  for  A1  and  Zn  maybe  at  once 
added  to  the  hydrochloric  solution  of  the  precipitate.  The  group-tests  in  this  table  are  H2S,  AmHS,  and  Am2C02. 


16G 


THE  METALLIC  RADICALS. 


QUESTIONS  AND  EXEEGTSES. 

269.  What  is  the  composition  and  source  of  the  Black  Antimony 
of  pharmacy? 

270.  In  what  alloys  is  metallic  antimony  a characteristic  in- 
gredient ? 

271.  What  is  the  quantivalence  of  antimony  as  far  as  indicated 
by  the  formulae  of  the  official  preparations  ? 

272.  By  a diagram  show  how  “Butter  of  Antimony”  is  prepared. 

273.  Write  out  equations  or  diagrams  expressive  of  the  reactions 
which  occur  in  converting  chloride  of  antimony  into  oxide. 

274.  What  is  the  formula  of  Tartar  Emetic? 

275.  Explain  the  official  process  for  the  preparation  of  Oxysul- 
phide  of  Antimony  [Antimonium  Sulphuratum,  B.  P.)  by  aid  of 
diagrams. 

276.  Give  a comparative  statement  of  the  tests  forarsenicum  and 
antimony. 

277.  How  is  antimony  detected  in  the  presence  of  arsenicum? 

278.  How  may  arsenicum  and  iron  be  distinguished  analytically? 

279.  Describe  a method  by  which  antimony,  magnesium,  and  iron 
may  be  separated  from  each  other. 

280.  Draw  out  an  analytical  chart  for  the  examination  of  an 
aqueous  liquid  containing  salts  of  arsenicum,  zinc,  calcium,  and 
ammonium. 


COPPER,  MERCURY,  LEAD,  SILVER. 

These  metals,  like  arsenicum  and  antimony,  are  precipitated  from 
acidified  solutions  by  sulphuretted  hydrogen,  in  the  form  of  sulphides ; 
but  the  sulphides,  unlike  those  of  arsenicum  and  antimony,  are  in- 
soluble in  alkalies.  The  atom  of  copper  is  usually  bivalent,  Cu” ; 
mercury  bivalent  in  the  mercuric  salts,  Hg",  and  univalent  in  the 
mercurous  salts,  Hg';  lead  sometimes  quadrivalent,  Pb"",  but 
generally  exerting  only  bivalent  activity,  Pb" ; and  silver  univalent, 
Ag'. 


COPPER. 

Symbol  Cu.  Atomic  weight  63.5. 

Source. — The  commonest  ore  of  this  metal  is  copper  pyrites,  a 
double  sulphide  of  copper  and  iron,  raised  in  Cornwall ; Australia 
and  Russia  supply  malachite,  a mixed  carbonate  and  hydrate;  much 
ore  is  also  imported  from  South  America.  It  is  smelted  in  enor- 
mous quantities  at  Swansea,  South  Wales,  a locality  peculiarly 
fitted  for  the  operation  on  account  of  its  proximity  to  the  coal-fields, 
and  its  position  as  a sea-coast  town — these  advantages  at  all  times 
insuring  cheap  fuel  and  freightage  to  the  different  metallurgical 
establishments. 


COPPER. 


16T 


Alchemy. — The  alchemists  termed  this  metal  Venus,  perhaps  on 
account  of  the  beauty  of  its  lustre,  and  gave  it  her  symbol  a 
compound  hieroglyphic  also  indicating  a mixture  of  gold  © and  a 
certain  hypothetical  substance  called  acrimony  the  corrosive  na- 
ture of  which  was  symbolized  by  the  points  of  a Maltese  cross.  To 
this  day  the  blue  show-bottle  in  the  shop-window  of  the  pharmacist  is 
occasionally  ornamented  by  such  a symbol,  indicative,  possibly,  of 
the  fact  that  the  blue  liquid  in  the  vessel  is  a preparation  of  copper. 

Coinage. — The  material  of  British  copper  coinage  is  now  a bronze 
mixture  composed  in  100  parts  by  weight  of  95  copper,  4 tin,  and  1 
zinc,  the  same  as  in  the  copper  coinage  of  France.  The  penny  is 
coined  at  the  rate  of  48  pence  in  one  pound  avoirdupois,  of  7000 
grains,  or  453.6  grammes ; the  halfpenny  at  80  in  the  pound  avoirdu- 
pois, and  the  farthing  at  160.  British  bronze  coins  are  a legal  tender 
in  payments  to  the  amount  of  Is. 

Metallic  Copper  ( Cuprum,  B.  P.  and  IT.  S.  P.)  in  the  form  of 
fine  wire,  about  No.  25,  is  used  in  preparing  Spiritus  ^theris 
Nitrosi,  B.  P.  and  U.  S.  P.  Copper  Foil,  B.  P.,  is  “ pure  metallic 
copper,  thin  and  bright.” 

Quantivalence. — Copper  forms  two  classes  of  salts ; in  one  the 
atom  is  bivalent  (Cu"),  in  the  other  exerts  univalent  activity  (CU2"). 
The  former  are  of  primary  importance,  the  latter  being  for  the  most 
part  unstable  and  wanting  in  technical  interest.  Their  compounds 
are  distinguished  as  cupric  and  cuprous ; but  those  of  the  higher 
class  only  have  general  interest,  and  will  be  almost  exclusively 
alluded  to  in  the  following  paragraphs.  Cuprous  iodide  (CU2I2)  will 
subsequently  be  referred  to  as  a convenient  form  in  which  to  remove 
iodine  from  solution,  and  the  formation  of  cuprous  oxide  (CU2O), 
under  given  circumstances,  as  an  indicator  of  the  presence  of  sugar 
in  a liquid. 


Reactions  having  (a)  Synthetical  and  (b)  Analytical 
Interest. 

(a)  Synthetical  Reactions. 

The  processes  for  the  following  salts  include  the  only 
synthetical  copper-reactions  having  any  medical  or  phar- 
maceutical interest:  1,  cupric  oxide,  the  black  oxide  of 
copper,  by  heating  a piece  of  copper  to  low  redness  on  a 
piece  of  earthenware  'in  an  open  fire  ; 2,  cupric  sulphate, 
the  common  sulphate  of  copper,  by  boiling  black  oxide  of 
copper  and  about  an  equal  weight  of  sulphuric  acid  in 
water,  filtering,  and  setting  aside  the  solution  so  that 
crystals  may  form  on  cooling  ; and,  3,  the  preparation  of 
solution  of  ammonio-sulphate  of  copper  (see  p.  153  ; also  p. 
168). 


168 


THE  METALLIC  RADICALS. 


Cu,  + Oj  = 2CuO 

Copper.  Oxygen.  Cupric 

oxide. 

CuO  + H,SO,  z=  CuSO,  + H.p 

Cupric  Sulphuric  Cupric  Water. 

oxide.  acid.  sulphate. 

Sulphate  of  Copper  [Cupri Sulphas,  B.  P.  and  U.  S.  P.)  (CUSO4, 
5H2O),  blue  vitriol,  hluestone,  or  cupric  sulphate,  is  the  only  copper 
salt  of  much  importance  in  Pharmacy.  It  is  a by-product  in  silver- 
refining  (2Ag2S04  + Cu2  = 2CUSO4  + 2Ag2).  It  is  also  formed  by 
roasting  copper  pyrites.  In  the  latter  operation  the  sulphide  of  iron 
and  sulphide  of  copper  are  oxidized  to  sulphates ; but  the  low  red 
heat  employed  decomposes  the  sulphate  of  iron,  w^hile  the  sulphate 
of  copper  is  unaffected ; it  is  purified  by  crystallization  from  a hot 
aqueous  solution,  though  frequently  much  sulphate  of  iron  remains 
in  the  crystals.  Sulphate  of  copper  results  on  'dissolving  in  diluted 
sulphuric  acid  the  black  oxide  (CuO)  obtained  in  annealing  copper 
plates  ; it  may  also  be  prepared  by  boiling  copper  with  three  times 
its^weight  of  sulphuric  acid  (2H2SO4+  Ou  = CUSO4+  SO2+  2H2O), 
diluting,  filtering,  evaporating,  and  crystallizing. 

Anhydrous  Sulphate  of  Copper  (CUSO4),  is  a yellowish-white 
powder  prepared  by  depriving  the  ordinary  blue  crystals  of  sulphate 
of  copper  of  their  water  of  crystallization  by  exposing  to  a tempera- 
ture of  about  400^  F.  It  is  used  in  testing  alcohol  and  similar  liquids 
for  water,  becoming  blue  if  the  latter  be  present. 

Verdigris  (from  verde-gris,  Sp.  green-gray)  is  a Subacetate  ( Cu~ 
pri  Subacetas,  U.  S.  P.)  or  Oxyacetate  of  Copper  (B.  P.)  (CU2O2C2 
H3O2),  obtained  by  exposing  alternate  layers  of  copper  and  ferment- 
ing refuse  grape-husks  to  the  action  of  air.  Digested  with  twice  its 
weight  of  acetic  acid  and  a little  water,  the  mixture  being  evaporated 
to  dryness  and  the  residue  dissolved  in  water,  it  forms  the  official 
Solution  of  Acetate  of  Copper  (CU2C2H3O2). 

The  modes  of  forming  cupric  sulphide,  hydrate,  oxide,  f error 
cyanide,  and  arsenite,  as  well  as  the  precipitation  of  metallic  copper, 
are  incidentally  alluded  to  in  the  following  analytical  paragraphs. 

(6)  Reactions  having  Analytical  Litere^  (Tests.) 

First  Analytical  Reaction. — Pass  sulphurofeecl  hydrogen 
through  an  acidified  solution  of  a copper  (sulphate, 
for  example)  ; black  cupric  sulphide  (OuS)'fa^t 

Second  Analytical  Reaction. — Add  sulpM^ftte  of  am- 
monium to  an  aqueous  copper  solution  ; cutfgK^ulphide  is 
again  precipitated,  insoluble  in  ex(^es^. 

Note. — Cupric  sulphide  is  not  altogether  insolublj^^fculphydratc 
of  ammonium  if  free  ammonia  or  nuich  aniihoniatedlfiBbe  present; 
it  is  quite  insoluble  in  the  fixed  alkaline)siiiphides. 

Third  Analytical  Reaction. — Imii^’se  a pi®  of  iron  or 
steel,  such  as  the  point  of  a penlpii^mr  a piewof  wire,  in 


I 


COPPER.  169 

a few  drops  of  a copper  solution  ; the  copper  is  deposited, 
: of  characteristic  color,  an  equivalent  quantity  of  iron 
> passing  into  solution. 

I By  this  reaction  copper  may  be  recovered  on  the  larger  scale  from 
; waste  solutions,  old  hoop  or  other  scrap  iron  being  thrown  into  the 
I liquors. 

I Fourth  Analytical  Reaction. — Add  ammonia  to  a cupric 
i solution;  cupric  hydrate  (Cu2HO)  of  a light-blue  color  is 
I precipitated.  Add  excess  of  ammonia ; the  precipitate  is 
redissolved,  forming  a blue  solution  of  ammonio-salt  of 
I copper,  so  deep  in  color  as  to  render  ammonia  an  exceed- 
I ingly  delicate  test  for  this  metal, 
i 

j An  ammonio-sulphate  of  copper  may  be  obtained  in  large  crystals 
by  adding  strongest  solution  of  ammonia  to  powdered  sulphate  of 
copper  until  the  salt  is  dissolved,  placing  the  liquid  in  a test-glass  or 
cylinder,  cautiously  pouring  in  twice  its  volume  of  strong  alcohol  or 
methylated  spirit,  taking  care  that  the  liquids  do  not  become  mixed 
tying  over  the  vessel  with  bladder,  and  setting  aside  for  some  weeks 
in  a cool  place.  ( Wittstein.)  The  constitution  of  ammonio-sulphate 
I and  other  ammonio-salts  of  copper  and  coresponding  salts  of  silver 
will  be  alluded  to  in  connection  with  “ white  precipitate,”  the  official 
“ ammoniated  mercury.” 

Cuprum  Ammoniatum,  U.  S.  P,,  is  an  ammonia-sulphate  of  cop- 
per prepared  by  rubbing  together  sulphate  of  copper  and  carbonate 
01  ammonium  until  effervescence  ceases,  and  drying  the  product. 

Fifth  Analytical  Reaction,— AM  solution  of  potash  or 
! soda  to  a cupric  solution  ; cupric  hydrate  (Cu2H0)  is  pre- 
jcipitated,  insoluble  in  excess.  Boil  the  mixture  in  the 
1 test-tube  j the  hydrate  is  decomposed,  losing  the  elements 
; of  water,  and  becoming  the  black  anhydrous  oxide  (CuO). 

^ Sixth  Analytical  Reaction, — Add  solution  of  ferrocyanide 
I of  potassium  (K^Fcy)  to  an  aqueous  cupric  solution;  a 
I reddish-brown  precipitate  of  cupric  ferrocyanide  (Cu  Fey) 

I falls.  This  also  is  a delicate  test  for  cojDper. 

I Seventh  Analytical  Reaction, — To  a cupric  solution  add 
: solution  of  arsenic,  and  cautiously  neutralize  with  alkali  • 
green  cupric  arsenite  (CuHAsOg)  falls.  ’ 

Note.  This  precipitate  has  been  already  mentioned  under  arseni- 
cuni.  An  arsenicum  salt  is  thus  a test  for  copper,  as  a copper  salt 
IS  tor  arsenicum— a remark  that  may  obviously  be  extended  to  most 
analytical  reactions ; for  the  body  acted  upon  characteristically  by 
■a  reagent  ts  as  good  a test  for  the  reagent  as  the  reagent  is  for  it ; 
'search  I’^^gent  when  the  other  body  is  the  object  of 

15 


no 


THE  METALLIC  RADICALS. 


Antidotes. — In  cases  of  poisoning  by  compounds  of  cop- 
per, iron  filings  should  be  administered,  the  action  of  which 
has  just  been  explained  (see  third  analytical  reaction). 
Ferrocyanide  of  potassium  may  also  be  given  (see  sixth 
anal3^tical  reaction).  Albumen  forms,  with  copper,  a com- 
pound insoluble  in  water ; hence  raw  eggs  should  be  swal- 
lowed, vomiting  being  induced  or  the  stomach-pump  applied 
as  speedily  as  possible. 


QUESTIONS  AND  EXERCISES. 

281.  What  are  the  relations  of  copper,  mercury,  lead,  and  silver  to 
each  other  and  to  arsenicum  and  antimony  ? 

282.  Name  the  sources  of  copper. 

283.  What  proportion  of  copper  is  contained  in  English  and  French 

copper”  coins  ? 

284.  Give  diagrams  showing  how  Sulphate  of  Copper  is  prepared 
on  the  small  and  large  scales. 

285.  Work  out  a sum  showing  how  much  Crystallized  Sulphate 
of  Copper  may  be  obtained  from  100  parts  of  sulphide  ? — Ans.  26I5. 

286.  How  may  Oxide  of  Copper  be  prepared  ? 

287.  Mention  the  formula  of  Verdigris. 

288.  Name  a good  clinical  test  for  copper. 

289.  What  is  the  analytical  position  of  copper  ? 

290.  Mention  the  chief  tests  for  copper. 

291.  How  may  copper  be  separated  from  arsenicum  ? 

292.  Why  is  finely  divided  iron  an  effective  antidote  in  cases  of 
poisoning  by  copper  ? 


MERCURY. 

Symbol  Hg.  Atomic  weight  200. 

Molecular  weight  200  {not  double  the  atomic  weight). 

Source. — Mercury  occurs  in  nature  as  sulphide  (HgS),  forming  the 
ore  cinnabar  (an  Indian  name  expressive  of  something  red),  and  is 
obtained  from  Spain,  California,  Eastern  Hungary,  China,  Japan, 
and  Peru. 

Preparation. — The  metal  is  separated  by  roasting  off  the  sulphur 
and  then  distilling,  or  distilling  with  lime,  which  combines  with  and 
retains  the  sulphur. 

Properties. — Mercury  {Hydrargyrum,  B.  P.  and  U.  S.  P.)  is  a 
silver-white  lustrous  metal,  liquid  at  common  temperature.  It  boils  at 
662^  F.,  and  at  — 40^  F.  solidifies  to  a malleable  mass  of  octahedral 
crystals.  When  quite  free  from  other  metals  it  does  not  tarnish,  and 


MERCURY. 


in 


its  globules  roll  freely  over  a sheet  of  white  paper  without  leaviug 
any  streak  or  losing  their  spherical  form. 

Formula. — The  formula  of  the  mercury  molecule  is  Hg  and  not 
Hg.^,  because  at  all  ordinary  temperatures  two  volumes,  which  if 
hydrogen  would  weigh  two  parts  (H2)  or  oxygen  thirty-two  parts 
(O2),  in  the  case  of  mercury  vapor  weigh  only  two  hundred  parts 
(Hg) ; that  is,  only  once  the  atomic  weight,  not  twice.  That  200, 
and  not  100,  is  the  atomic  weight  of  mercury  is  shown  by  the  fact 
that  200  is  the  minimum  proportion  relative  to  1 of  hydrogen  in 
which  mercury  combines,  and  by  its  relations  to  heat.  Still  it  is 
difficult  to  imagine  an  atom  existing  in  the  free  state  in  nature ; and 
the  suggestion  has  been  made  that  (as  is  proved  to  be  the  case  with 
sulphur)  mercury,  as  we  know  it,  is  in  abnormal  condition,  and  that 
if  the  weight  of  its  vapor  could  be  taken  at  a low  temperature  or 
under  some  other  condition,  its  molecular  weight  might  be  found  to 
be  400.  Similar  remarks  may  be  made  respecting  zinc,  the  molecular 
weight  of  which,  so  far  as  we  know,  is  identical  with  its  atomic  weight. 

Medicinal  Compounds.  — The  compounds  of  mercury  used  in 
medicine  are  all  obtained  from  the  metal.  The  metal  itself,  rubbed 
with  chalk  or  with  confection  of  roses  and  powdered  liquorice-root, 
or  wdth  lard  and  suet,  until  globules  are  not  visible  to  the  unaided 
eye,  is  often  used  in  medicine.  The  preparations  are  : the  Hydrar- 
gyrum cum  Greta,  B.  P.  and  IT.  S.  P.,  or  “ Gray  Powder  f Pilula 
Hydrargyri,  B.  P.  and  U.  S.  P.,  or  “ Blue  Pill and  Unguentum 
Hydrargyri,  B.  P.  and  U.  S.  P.,  or  “ Blue  Ointment.”  There  are 
also  a Compound  Ointment,  a Plaster  of  Mercury,  a Plaster  of  Am 
moniacum  and  Mercury,  a Liniment,  and  a Suppository.  Their 
therapeutic  effects  are  probably  due  to  the  black  and  red  oxide 
which  occur  in  them  through  the  action  of  the  oxygen  of  the  air  on 
the  finely-divided  metal.  The  proportion  of  oxide  or  oxides  varies 
according  to  the  age  of  the  specimen. 

Mercurous  and  Mercuric  Compounds.’ — Mercury  combines  wdth 
other  elements  and  radicals  in  two  proportions : those  compounds  in 
which  the  other,  acidulous,  radicals  are  in  the  lesser  amount  are 
termed  mercurous,  the  higher  being  mercuric.  Thus,  calomel 
(HgCl)*  is  mercurous  chloride,  while  corrosive  sublimate  (HgCh^)  is 
mercuric  chloride.  In  every  pair  of  mercury  compounds  the  mercu- 
ric contains  twice  as  much  complementary  radical,  in  proportion  to 
the  mercury,  as  the  mercurous. 

Note  on  Nomenclature. — The  remarks  made  concerning  the  two 
classes  of  iron  salts,  ferrous  and  ferric  (p.  120),  apply  in  the  main  to 
the  two  series  of  mercury  salts.  The  latter  are  systematically  dis- 
tinguished in  most  modern  works  by  the  terms  mercurous  and  mer- 
curic. In  the  British  and  United  States  Pharmacopoeias,  however, 
which  include  only  a few  in  comparison  with  the  whole  number  of 
mercury  salts,  older  and  more  strongly  contrasted  names  are  em- 
ployed, thus  : — 

* The  specific  gravity  of  the  vapor  of  calomel,  and  the  fact  that  the 
salt  is  not  decomposed  at  the  temperature  at  which  its  specific  gravity 
is  taken,  show  that  the  formula  of  calomel  is  HgCl,  and  not  Hg.^CI^. 


172 


THE  METALLIC  RADICALS. 


Systematic  names. 


Official  names. 


Mercurous  iodide 
Mercuric  iodide  . 
Mercurous  nitrate 
Mercuric  nitrate 


Green  iodide  of  mercury, 
Eed  iodide  of  mercury. 
Not  mentioned  in  13.  F. 
Nitrate  of  mercury. 


Mercuric  sulphate 
Mercurous  chloride 
Mercuric  chloride 
Mercurous  oxide 
Mercuric  oxide  . 


Mercurous  sulphate 


Not  mentioned  in  B.  P. 
Sulphate  of  mercury. 


Subchloride  of  mercury. 
Perchloride  of  mercury. 
Black  oxide  of  mercury. 
Red  oxide  of  mercury. 


Specific  Gravity. — Mercury  is  13.6  times  as  heavy  as  water. 
Amalgams. — The  compound  formed  in  fusing  metals  together  is 
usually  termed  an  alloy  [ad  and  ligo,  to  bind) ; but  if  mercury  is  a 
constituent,  an  amalgam  [jxdxayya  malagma,  from  malasd, 

to  soften,  the  presence  of  mercury  lowering  the  melting  point  of  such 
a mixture).  Most  metals,  even  hydrogen,  according  to  Leow,  form 
amalgams. 

Reaction  having  (a)  Synthetical  and  (6)  Analytical 
Interest. 


(a)  Synthetical  Reactions. 

The  Two  Iodides. 


First  Synthetical  Reaction. — Rub  together  a small  quan- 
tity of  mercuiy  and  iodine,  controlling  the  rapidity  of  com- 
bination by  adding  a few  drops  of  spirit  of  wine,  which,  by 
evaporation,  carries  off  heat,  and  thus  keeps  down  tempera- 
ture. The  product  is  either  mercuric  iodide,  mercurous 
iodide,  or  a mixture  of  the  two,  as  well  as  mercury  or 
iodine  if  excess  of  either  has  been  emplo3^ed.  If  the  two 
elements  have  been  previously  weighed  in  single  atomic 
proportions,  200  of  mercury  to  127  of  iodine  (about  8 to  5, 
or  1 ounce  of  mercury  to  278  grains  of  iodine),  the  mercu- 
rous or  green  (grayish-green)  iodide  results  (Hgl  [Hy- 
drargyri  lodidum  Viride.,  B.  P.  and  U.  S.  P.) ; if  in  the 
proportion  of  one  atom  of  mercury  to  two  atoms  of  iodine 
(200  to  twice  127,  or  about  4 to  5),  the  mercuric  or  red 
iodide,  Hglg,  results,  an  iodide  that  is  also  official,  but 
made  in  another  yvsiy.  (See  page  174.)  The  green  iodide 
should  be  made  and  dried  (without  heat)  with  as  little 
exposure  to  light  as  possible. 

Mercurous  iodide  is  decomposed  slowly  by  light,  and  quickly  by 
heat,  into  mercuric  iodide  and  mercury.  Mercuric  iodide  occurring 
as  an  impurity  in  mercurous  iodide  may  be  detected  by  digesting  in 


MERCURY. 


173 


ether  (in  which  mercurous  iodide  is  insoluble),  filtering  and  evapo- 
rating to  dryness ; mercuric  iodide  remains.  Mercuric  iodide  is 
stable,  and  may  be  sublimed  in  scarlet  crystals  without  decomposi- 
tion. (For  details  of  the  method  by  which  a specimen  of  the  crystals 
may  be  obtained,  and  the  precautions  to  be  observed,  vide  “ corro- 
sive sublimate,’^  p.  176.) 

Relation  of  Mercuric  Iodide  to  Light. — In  condensing,  mercuric 
iodide  is  at  first  yellow,  afterwards  acquiring  its  characteristic  scar- 
let color.  This  may  be  shown  by  smearing  or  rubbing  a sheet  of 
white  paper  with  the  red  iodide,  and  then  holding  the  sheet  before  a 
fire  or  over  a flame  for  a few  seconds.  As  soon  as  the  paper  becomes 
hot  the  red  instantly  changes  to  yellow,  and  the  salt  does  not  quickly 
regain  its  red  color,  even  when  cold,  if  the  paper  is  carefully  handled. 
But  if  a mark  be  made  across  the  sheet  by  anything  at  hand,  or  the 
salt  be  pressed  or  rubbed  in  any  way,  the  portions  touched  immedi- 
ately return  to  the  scarlet  condition.  According  to  Warington, 
this  change  is  consequent  upon  rhomboidal  crystals  being  converted 
into  octahedra  with  a square  base,  and  will  serve  as  an  excellent 
illustration  of  the  influence  of  physical  structure  in  causing  color. 
The  yellow  modification  so  acts  on  the  rays  of  white  light  shining  on 
its  particles  as  to  absorb  the  violet  and  reflect  the  complementary 
hue,  the  yellow,  which,  entering  the  eye  of  the  observer,  strikes  his 
retina,  and  thus  conveys  to  the  brain  the  impression  of  yellowness ; 
and  the  red  modification,  though  actually  the  same  chemical  sub- 
stance, is  sufficiently  different  in  the  structure  of  its  particles  to 
absorb  the  green  constituent  of  white  light  and  reflect  the  comple- 
mentary ray,  the  red. 

Illustration  of  the  Chemical  law  of  Midtiple  Proportions  (p.  42). 
— Applying  the  atomic  theory  to  the  above  iodides,  it  will  at  once 
be  apparent  why  mercury  and  iodine  should  combine  in  the  proportion 
of  200  of  mercury  with  either  127  or  254  of  iodine,  and  not  with  any 
intermediate  quantity.  For  it  is  part  of  that  theory  that  masses  are 
composed  of  atoms,  and  that  atoms  are  indivisible ; and  that  the 
weight  of  the  atom  of  mercury  is  to  that  of  iodine  as  200  is  to  127. 
Mercury  and  iodine  can  only  combine,  therefore,  in  atomic  propor- 
tions, atom  to  atom  (which  is  the  same  as  200  to  127),  or  one  atom 
to  two  atoms  (which  is  the  same  as  200  to  254).  To  attempt  to  com- 
bine them  in  any  intermediate  proportion  would  be  useless,  a mere 
mixture  of  the  two  iodides  would  result.  A higher  proportion  of 
mercury  than  200  to  127  of  iodine  gives  but  a mixture  of  mercurous 
iodide  and  mercury ; a higher  proportion  of  iodine  than  254  to  200 
of  mercury  gives  but  a mixture  of  mercuric  iodide  and  iodine.  Or, 
for  example,  200  grains  of  mercury,  mixed  with,  say,  200  of  iodine, 
would  yield  139  grains  of  mercurous  iodide,  and  261  grains  of  mer- 
curic iodide ; for  the  200  grains  of  mercury  uniting  with  127  grains 
of  the  iodine  gives,  for  the  moment,  327  grains  of  mercurous  iodide 
and  73  grains  of  iodine  still  free.  The  73  grains  of  iodine  will  im- 
mediately unite  with  188  grains  of  the  mercurous  iodide  (for  if  127 
of  I require  327  of  Hgl  to  form  Hgl.^,  73  will  require  188),  and  form 
261  grains  of  mercuric  iodide,  diminishing  the  327  grains  of  mercu- 
rous iodide  to  139  grains. 


15* 


n4 


THE  METALLIC  RADICALS. 


Preparation  of  Red  Iodide  of  Mercury  by  precipitation. 
— To  a few  drops  of  a solution  of  a mercuric  salt  (corrosive 
sublimate,  for  example),  add  solution  of  iodide  of  potas- 
sium, drop  by  drop  ; a precipitate  of  mercuric  iodide,  Hgl.^, 
forms,  and  at  first  quickly  redissolves,  but  is  permanent 
when  sufficient  iodide  of  potassium  has  been  added.  Con- 
tinue the  addition  of  iodide  of  potassium;  the  precipitate 
is  once  more  redissolved. 

Note. — When  first  precipitated,  mercuric  iodide  is  yellowish-red, 
but  soon  changes  to  a beautiful  scarlet.  Its  solubility  either  in  solu- 
tion of  the  mercuric  salt  or  in  solution  of  iodide  of  potassium  renders 
the  detection  of  a small  quantity  of  a mercuric  salt  by  iodide  of 
potassium,  or  a small  quantity  of  an  iodide  by  a mercuric  solution, 
difficult,  and  hence  lessens  the  value  of  the  reaction  as  a test.  But 
the  reaction  has  synthetical  interest,  the  method  by  precipitation 
being  that  adopted  in  the  British  and  United  States  Pharmacopoeias 
[Hydrargyri  lodidum  Rubrum,^.  P.  and  U.  S.  P.).  Mercuric  iodide 
thus  made  has  the  same  composition  as  that  prepared  by  direct  com- 
bination of  its  elements.  Equivalent  proportions  of  the  two  salts 
must  be  used  in  making  the  preparation  (HgCl2  = 271 ; 2KI  = 
332).  About  4 parts  of  corrosive  sublimate  are  dissolved  in  50  or 
60  of  water  (w^armth  quickens  solution)  and  5 of  iodide  of  potassium 
in  15  or  20  of  water,  the  solutions  mixed  and  the  precipitate  collected 
on  a filter,  drained,  washed  twice  with  distilled  water,  and  dried  on 
a plate  over  a water-bath.  The  mercury  in  mercuric  or  mercurous 
iodide  is  set  free  and  sublimes  in  globules  on  heating  either  powder 
with  dried  carbonate  of  sodium  in  a test-tube ; the  iodine  may  be 
detected  by  digesting  with  solution  of  soda,  filtering,  and  to  the  solu- 
tion of  iodide  of  sodium  thus  formed  adding  starch  paste  and  acidu- 
lating with  nitric  acid,  when  blue  iodide  of  starch  results. 

HgCl^  -f  2KI  = Hgl^  + 2KC1 

Mercuric  Iodide  of  Mercuric  Chloride  of 

chloride.  potassium.  iodide.  potassium. 

Mercuric  iodide  is  insoluble  in  water,  slightly  soluble  in  alcohol, 
tolerably  soluble  in  ether.  Precipitated  red  iodide  of  mercury  mixed 
with  white  wax,  lard,  and  oil,  forms  the  Unguentum  Hydrargyri 
lodidi  Rubric  B.  P.  and  U.  S.  P.  Donovan's  Solution  contained 
mercuric  and  arsenious  iodides. 

The  Two  Nitrates. 

Second  Synthetical  Reaction. — Mix  a little  nitric  acid 
in  a test-tube  with  four  or  five  times  its  bulk  of  water,  add 
a small  globule  of  mercury,  and  set  the  tube  aside  for  a few 
hours,  in  a cool  place  ; solution  of  mercurous  nitrate 
(llgXO.^)  will  be  formed,  and  nitric  oxide  (NO)  evolved. 
The  solution  may  be  retained  for  subsequent  analytical 
operations. 

Hg3  + 4IINO3  = SIIgNO^  + 2H,0  -f  NO. 


MERCURY. 


n5 


Third  Synthetical  Reaction. — Place  mercury  in  strong 
nitric  acid,  and  warm  the  mixture;  mercuric  nitrate  is 
formed,  and  will  be  deposited  in  crystals  as  the  solution 
cools.  Retain  the  product  for  a subsequent  experiment. 

The  mercuric  nitrates  vary  somewhat  in  composition,  according 
to  the  proportion,  strength,  and  temperature  of  the  acid  used  in  their 
formation.  A mercuric  nitrate  may  be  obtained  having  the  formula 
Hg2N03. 

Hg3  + 8HNO3  = 3(Hg2N03)  + 2N0  + 4H,0 

Mercury.  Nitric  Mercuric  Nitric  Water, 

acid.  nitrate.  oxide. 

Mercuric  Oxynitrates. — From  the  normal  mercuric  nitrate  several 
oxynitrates  may  be  obtained.  Thus  on  merely  evaporating  a solu- 
tion of  mercuric  nitrate,  and  cooling,  crystals  having  the  formula 
Hg6036N03  are  deposited.  The  latter,  by  washing  with  cold  water, 
yield  a yellow  pulverulent  oxynitrate,  Hgs044N03 : mixed  with  lard, 
this  has  sometimes  been  used  as  an  ointment.  Boiled  in  water,  the 
yellow  gives  a hrick-red  oxynitrate,  Hgg052N03. 

The  Pharmacopoeial  preparations  of  mercuric  nitrate  are  Liquor 
Hydrargyri  Nitratis  Acidus,  B.  P.  (sp.  gr.  2.246  ; U.  S.  P.,  sp.  gr. 
2.165),  and  TJnquentum  Hydrargyri  Nitratis,  B.  P.  and  U.  S.  P. 
The  former  (B.  P.)  is  made  by  placing  four  ounces  of  mercury  in  five 
fiuidounces  of  nitric  acid  diluted  with  an  ounce  and  a half  of  water, 
and,  when  the  metal  is  dissolved,  boiling  gently  for  fifteen  minutes. 

The  Two  Sulphates. 

Fourth  Synthetical  Reaction. — Boil  two  or  three  grains 
of  mercury  with  a few  drops  of  strong  sulphuric  acid  in  a 
test-tube ; sulphurous  acid  gas  (SO.J  is  evolved,  and  mer- 
curic sulphate  {Hydrargyri  Sulphas^  B.  P.)  (HgSOJ  re- 
sults— a white  heavy  crystalline  powder. 

Hg  -h  2H,SO,  = HgSO,  + SO,  + 2HO 

Mercury.  Sulphuric  Mercuric  Sulphurous  Water. 

Hcid.  sulphate.  acid  gas. 

Between  two  and  three  ounces  of  mercuric  sulphate  may 
be  prepared  from  a fluidrachm  of  mercury  and  a fluidounce 
of  sulphuric  acid  boiled  together  in  a small  dish.  These 
are  the  official  proportions.  The  operation  is  completed 
and  any  excess  of  acid  removed  by  evaporating  the  mix- 
ture of  metal  and  liquid  to  dryness,  either  in  the  open  air 
or  in  a fume-chamber,  sulphuric  acid  vapors  being  exces- 
sively irritating  to  the  mucous  membrane  of  the  nose  and 
throat;  dry  crystalline  mercuric  sulphate  remains.  If 
residual  particles  of  mercury  are  observed,  the  mass  should 
be  damped  with  sulphuric  acid  and  again  heated. 


1Y6  THE  METALLIC  RADICALS. 

By-Products.-. — In  clieniical  manufactories,  secondary  products, 
such  as  the  sulphurous  gas  of  the  above  reaction,  are  termed  by-pro- 
ducts, and,  if  of  value,  are  utilized.  In  the  present  case  the  gas  has 
no  immediate  interest,  and  is  therefore  allowed  to  escape.  When 
very  pure  sulphurous  acid  gas  is  required  for  experiments  on  the 
small  scale,  this  would  be  the  best  method  of  making  it,  a delivery- 
tube  being  adapted  by  a cork  to  the  mouth  of  a flask  containing  the 
acid  and  metal.  The  sulphate  of  mercury  would  then  become  the 
by-product. 

Mercuric  Oxy sulphate. — Water  decomposes  mercuric  sulphate 
into  a soluble  acid  salt  and  an  insoluble  yellow  oxysulphate  (Hg302 
SO4).  The  latter  is  called  Turpeth  mineral,  from  its  resemblance 
in  color  to  the  powdered  root  of  Ipomoea  turpethum,  an  Indian  sub- 
stitute for  jalap.  The  yellow  sulphate  of  mercury  [Hydrargyri 
Sidphas  Flava,  U.  S.  P.)  was  formerly  official  in  the  pharmacopoeia 
of  Great  Britain,  but  is  now  seldom  used. 

Fifth  Synthetical  Reaction. — Rub  a portion  of  the  dry 
mercuric  sulpliate  of  the  previous  reaction  with  as  much 
mercury  as  it  alreadj'  contains  ; the  product,  when  the  two 
have  thoroughly  blended,  is  mercurous  sulphate  (Hg^SOJ: 
it  may  be  retained  for  a subsequent  experiment. 

Molecular  Weight. — The  exact  proportion  of  mercury  to  sulphate 
is  merely  a matter  of  calculation  ; for  the  combining  proportion  of  a 
compound  (if  it  possess  any  combining-power)  is  the  sum  of  the  com- 
bining proportions  of  its  constituents.  In  other  loords,  the  combin- 
ing iveight  of  a molecule  is  simply  the  sum  of  the  weights  of  its 
constituent  atoms,  or,  more  generally,  the  molecular  weight  of  a 
compound  is  the  sum  of  the  atomic  weights  of  its  elements.  In 
accordance  with  this  rule  (sometimes  called  the  fourth  law  of  chemi- 
cal combination,  though  only  a deduction  from  the  first — p.  41),  296 
of  mercuric  sulphate  and  200  of  mercury  (about  3 to  2)  are  the  exact 
proportions  necessary  to  the  formation  of  mercurous  sulphate. 

The  Two  Chlorides. 

Sixth  Synthetical  Reaction.  — Mix  thoroughly^  a few 
grains  of  dry  mercuric  sulphate  with  about  four-fifths  its 
weight  of  chloride  of  sodium,  and  heat  the  mixture  slowly^ 
in  a test-tube  in  a fume-chamber  or  in  the  open  air  to 
leeward  of  the  operator;  mercuric  chloride  (IlgCl.^),  or 
corrosive  sublimate  {Hydrargyri  Perchloridum^  B.  P., 
Hydrargyri  Chloridum  Cori'osivum^  U.  S.  P.),  sublimes 
and  condenses  in  the  upper  part  of  the  tube  in  heavy  color- 
less crystals  or  a cry^stalline  mass.  Somewhat  larger  quan- 
tities (in  the  proportion  of  20  of  sulphate  to  16  of  salt,  and, 
vide  infra.,  1 of  black  oxide  of  manganese)  may  be  sublimed 
in  a pair  of  two-ounce  or  three-ounce  round-bottomed  galli- 


MERCURY. 


17^ 


pots,  the  one  inverted  over  tlie  other,  and  the  joint  luted 
by  moist  fireclay  (the  powdered  clay  kneaded  with  water 
to  the  consistence  of  dough).  The  luting  having  been 
allowed  to  dry  (somewhat  slowly,  to  avoid  cracks),  the 
pots  are  placed  upright  on  a sand-tray  (plate-shape  answers 
very  well),  sand  piled  round  the  lower  and  a portion  of  the 
upper  pot,  and  the  whole  heated  over  a good-sized  gas 
fiame  for  an  hour  or  more.  Red  Iodide  of  Mercury  and 
Calomel  may  be  sublimed  in  the  same  way.  The  former 
requires  less,  the  latter  more,  heat  than  corrosive  subli- 
mate. 


HgSO,  + 2NaCl  = HgCl,  + 

Mercuric  Chloride  of  Mercuric  Sulphate  of 

sulphate.  sodium.  chloride.  sodium. 

Note. — If  the  mercuric  sulphate  contain  any  mercurous  sulphate, 
some  calomel  may  be  formed.  This  result  will  be  avoided  if  2 or  3 
per  cent,  of  black  oxide  of  manganese  be  previously  mixed  with  the 
ingredients,  the  action  of  which  is  to  eliminate  chlorine  from  the 
excess  of  chloride  of  sodium  used  in  the  process,  the  chlorine  convert- 
ing any  calomel  into  corrosive  sublimate.  Manganate  of  sodium  and 
a lower  oxide  of  manganese  are  simultaneously  produced. 

Precaution. — The  operation  is  directed  to  be  conducted  with  care 
in  a fume-chamber  or  in  the  open  air,  because  the  vapor  of  corrosive 
sublimate,  which  might  possibly  escape,  is  very  acrid  and  highly 
poisonous.  Its  vulgar  name  is  indicative  of  its  properties. 

Ten  grains  of  perchloride  of  mercury  and  the  same  quantity  of 
chloride  of  ammonium  in  one  pint  of  water,  form  the  Liquor  Hydrar- 
gyri  Perchloridi,  B.  P.  A dilute  aqueous  solution  of  perchloride 
of  mercury  is  liable  to  decomposition,  calomel  being  precipitated, 
water  formed,  and  oxygen  gas  evolved.  The  presence  of  excess  of 
chloride  of  ammonium,  with  a portion  of  which  the  mercuric  chloride 
forms  a stable  double  salt,  prevents  the  decomposition. 

Seventh  Synthetical  Reaction, — Mix  a few  grains  of  the 
mercurous  sulphate  of  the  fifth  reaction  with  about  a third 
of  its  weight  of  chloride  of  sodium,  and  sublime  in  a test- 
tube  ; crystalline  mercurous  chloride  (HgCl)  or  calomel 
{Hydrargyri  Subchloridum^  B.  P.,  Hydrargyri  Ghloridum 
3Iite^  U.  S.  P.)  results.  Larger  quantities  may  be  pre- 
pared in  the  manner  directed  for  corrosive  sublimate,  a 
somewhat  higher  temperature  being  employed ; similar 
precautions  must  also  be  observed.  The  proportions  are 
10  of  mercuric  sulphate  to  7 of  mercury  and  5 of  dry  chlo- 
ride of  sodium.  ‘‘  Moisten  the  sulphate  of  mercury  with 
some  of  the  water,  and  rub  it  and  the  mercury  together 
until  globules  are  no  longer  visible  ; add  the  chloride  of 
sodium,  and  thoroughly  mix  the  whole  by  continued  tritu- 


178 


THE  METALLIC  RADICALS. 


ration.  When  dry  sublime  by  a suitable  apparatus  into  a 
chamber  of  such  a size  that  the  calomel,  instead  of  adhering 
to  its  sides  as  a crystalline  crust,  shall  fall  as  a fine  (dull- 
white)  powder  on  its  floor.  Wash  this  powder  with  boiling 
distilled  water  until  the  washings  cease  to  be  darkened  by 
a drop  of  sulphydrate  of  ammonium.  Finally,  dry  at  a 
heat  not  exceeding  212®,  and  preserve  in  a jar  or  bottle 
impervious  to  light. 

Hg^SO,  + 2NaCl  = 2HgCl  + IsXSO; 

Mercurous  Chloride  of  Mercurous  Sulphate  of 

sulphate.  sodium.  chloride.  sodium 

The  term  calomel  [xaXo^,  Jcalos,  good,  and  melas,  black)  is 

said  to  relate  to  the  use  of  the  salt  as  a good  remedy  for  Mack  bile, 
but  probably  was  simply  indicative  of  the  esteem  in  which  black  sul- 
phide of  mercury  was  held,  the  compound  to  which  the  name  calomel 
was  first  applied. 

Test  for  corrosive  suMimate  in  calomel. — If  the  mercurous  sul- 
phate contains  mercuric  sulphate,  some  mercuric  chloride  will  also 
be  formed.'  Corrosive  sublimate  is  soluble  in  water,  calomel  insolu- 
ble ; the  presence  of  the  former  may  therefore  be  proved  by  boiling 
a few  grains  of  the  calomel  in  distilled  water,  filtering  and  testing 
by  sulphuretted  hydrogen  or  sulphydrate  of  ammonium  as  described 
hereafter.  If  corrosive  sublimate  is  present,  the  whole  bulk  of  the 
colomel  must  be  washed  with  hot  distilled  water  till  the  filtrate 
ceases  to  give  any  indications  of  mercury.  Corrosive  sublimate  is 
more  soluble  in  alcohol,  and  still  more  in  ether,  calomel  insoluble. 
Ether  in  which  calomel  has  been  digested  should,  therefore,  after 
filtration,  yield  no  residue  on  evaporation.  Calomel  is  converted 
by  hydrocyanic  acid  into  mercuric  salt,  with  separation  of  metallic 
mercury. 

Note. — The  above  process  is  that  of  the  Pharmacopoeias ; but 
calomel  may  also  be  made  by  other  methods.  Calomel  mixed  with 
lard  forms  the  Unguentum  Hydrargyri  Suhchloridi,  B.  P.,  and 
with  sulphurated  antimony,  guaiacum  resin,  and  castor  oil,  the  Pilula 
Hydrargyri  Suhchloridi  Composita,  B.  P.,  Pilula  Antimonii 
Comp>osita,  U.  S.  P.,  or  “ Plummer’s  Pills.” 

The  two  Oxides. 

Eighth  Synthetical  Reaction. — Evaporate  the  mercuric- 
nitrate  of  the  third  reaction  to  dryness  in  a small  dish,  in 
a fume-chamber,  or  in  the  open  air  if  more  than  a few 
grains  have  been  prepared,  and  heat  the  residue  till  no 
more  fumes  are  evolved;  mercuric  oxide  (HgO),  ‘‘Red 
Precipitate,”  the  Red  Oxide  of  Mercury  {Hydrargyri  Oxi- 
dum  Ruhrum,^  B.  P.  and  U.  S.  P.),  remains. 

2(Hg2N03)  = 2ITgO  -f  4NO,  -f  O., 

Mercuric  Mercuric  Nitric  Oxygen, 

nitrate.  oxide.  peroxide. 


MERCURY. 


179 


The  nitric  constituents  of  the  salt  may  be  partially  economized 
by  previously  thoroughly  mixing  with  the  dry  mercuric  nitrate  as 
much  mercury  as  is  used  in  its  preparation,  or  as  much  as  it  already 
contains  (ascertained  by  calculation  from  the  atomic  weights  and  the 
weight  of  nitrate  under  operation,  as  in  making  mercurous  sulphate 
^ p.  176),  and  well  heating  the  mixture.  In  this  case  the  free  mercury 
is  also  converted  into  mercuric  oxide.  This  is  the  official  process, 

\ the  Pharmacopoeial  quantities  being  four  ounces  of  mercury  dissolved 
; in  four  and  a half  fluidounces  of  nitric  acid  diluted  with  two  ounces 
' of  water,  the  solution  evaporated  to  dryness,  the  residue  thoroughly 
mixed  with  four  ounces  of  mercury,  and  the  whole  heated  until  acid 
vapors  cease  to  be  evolved.  (Mercuric  oxide  is  tested  for  nitrate 
by  heating  a little  of  the  sample  in  a test-tube,  when  orange  nitrous 
wapors  are  produced  and  are  visible  in  the  upper  part  of  the  tube, 
if  nitrate  is  present). 

Hg2N03  + Hg  = 2HgO  + 2NO2 

Mercuric  Mercury.  Murcuric  Nitric 

nitrate.  oxide.  peroxide. 

Mercuric  oxide  is  an  orange-red  powder,  more  or  less  crystalline 
according  to  the  extent  to  which  it  may  have  been  stirred  during 
preparation  from  the  nitrate,  much  rubbing  giving  the  crystals  a 
pulverulent  character.  Mixed  with  yellow  wax  and  oil  of  almonds 
it  yields  the  Unguentum  Hydrargyri  Oxidi  Ruhri,  B.  P.  (1  part 
in  8).  A similar  ointment  is  official  in  U.  S.  P.  Mercuric  oxide,  in 
contact  with  oxidizable  organic  matter,  is  liable  to  reduction  to  black 
or  mercurous  oxide. 

Ninth  Synthetical  Reaction. — To  solution  of  corrosive 
sublimate  in  a test-tube  or  larger  vessel  add  solution  of 
potash  or  soda,  or  lime-water ; yellow  oxide  of  mercury, 
Hydrargyri  Oxidum  Flavum^  U.  S.  P.,  or  mercuric  oxide 
(HgO),  is  precipitated. 

HgCl^  + Ca2HO  = HgO  + CaCl^  + H.,0 

Mercuric  Hydrate  of  Mercuric  Chloi-ide  of  Water. 

cMoride.  calcium.  oxide.  calcium. 

Eighteen  grains  of  corrosive  sublimate  to  ten  ounces  of  lime-water 
form  the  Lotio  Hydrargyri  FLava,  B.  P.  The  precipitate  only  dif- 
fers physically  from  the  red  mercuric  oxide  ; the  yellow  is  in  a more 
minute  state  of  division  than  the  red.  Mercuric  oxide  is  very  slightly 
soluble  in  water,  but  sufficiently  so  to  communicate  a decidedly 
metallic  taste. 

Tenth  Synthetical  Reaction. — To  calomel  add  solution 
of  potash  or  soda,  or  lime-water ; black  oxide  of  mercury, 
or  mercurous  oxide  (Hg^O).is  produced,  and  may’’  be  filtered 
off,  washed,  and  dried.  (This  reaction  and  the  formation 
; of  a white  curdy  precipitate,  on  the  addition  of  solution 
of  nitrate  of  silver  to  the  filtrate  from  the  mercurous 
oxide,  acidified  by  nitric  acid,  form  sufficient  evidence  of 


180 


THE  METALLIC  RADICALS. 


a powder  being  or  containing  calomel.  The  curdy  precipi- 
tate is  chloride  of  silver.) 

Thirty  grains  of  calomel  to  ten  ounces  of  lime-water  form  the  Lotto 
Hydrargyri  Nigra,  B.  P. 

2HgCl  + Ca2HO  = Hg,0  + CaCl,  + H^O 

Mercurous  Hydrate  of  Mercurous  Chloride  of  Water, 

chloride.  calcium.  oxide.  calcium. 


(5)  Analytical  Reactions  ( Tests), 

(The  mercury  occurring  as  mercuric  or  mercurous  saltj 

First  Analytical  Reaction, — The  Copper  Test,  Depcrsi- 
tion  of  mercury  upon,  and  sublimation  from  copper. — Plaice 
a small  piece  of  bright  copper,  about  half  an  inch  long  ' 
a quarter  of  an  inch  broad,  in  a solution  of  any  sal^ 
mercury,  mercurous  or  mercuric,  and  heat  in  a test-tube  , 
the  copper  becomes  coated  with  mercury  in  a fine  state  of 
division.  (The  absence  of  any  notable  quantity  of  nitric 
acid  must  be  insured,  or  the  copper  itself  will  be  dissolved. 
See  below.)  Pour  away  the  supernatant  liquid  from  the 
copper,  wash  the  latter  once  or  twice  by  pouring  water  into, 
and  then  out  of,  the  tube,  remove  the  metal,  take  off*  exc"' 
of  water  by  gentle  pressure  in  a piece  of  filter-pape^ 
the  copper  by  passing  it  quickly  through  a flame,  hQ.V 
it  by  the  fingers ; finally,  place  the  copper  in  a dry 
test-tube,  and  heat  to  redness  in  a flame,  the  tube 
held  in  a horizontal  position ; the  mercury  sublime.^ 
condenses  as  a white  sublimate  of  minute  globules  on  the 
cool  part  of  the  tube  outside  the  flame.  The  globules  ag- 
gregate on  gently  pressing  with  a glass  rod,  and  are  espe- 
cially visible  where  flattened  between  the  rod  and  the  side 
of  the  test-tube. 

Notes  on  the  Test. — This  is  a valuable  test,  for  several  reasons : 
It  is  very  delicate  when  performed  with  care.  It  brings  before  the 
observer  the  element  itself — one  which  from  its  metallic  lustre  and 
fluidity  cannot  be  mistaken  for  any  other.  It  separates  the  element 
both  from  mercurous  and  mercuric  salts.  Mercury  can  in  this  way 
be  readily  eliminated  in  the  presence  of  most  other  substances,  or- 
ganic or  inorganic. 

In  performing  the  test  the  presence  of  any  quantity  of  nitric  acid 
may  be  avoided  by  adding  an  alkali  until  a slight  permanent  preci- 
pitate appears,  and  then  reacidifying  with  a few  drops  of  acetic  or 
hydrochloric  acid ; or  by  concentrating  in  an  evaporating-dish  after 
adding  a little  sulphuric  acid. 


MERCURY. 


181 


Tests  continued.  (The  mercury  occurring  as  mercuric  salt.) 

Second  Analytical  Reaction,— To  a few  drops  of  a solu- 
tion of  a mercuric  salt  (corrosive  sublimate,  for  example) 
add  solution  of  iodide  of  potassium,  drop  by  drop  ; a preci- 
pitate of  mercuric  iodide  (HglJ  forms,  and  at  first  quickly 
redissolves,  but  is  permanent  when  sufficient  iodide  of 
potassium  has  been  added.  Continue  the  addition  of  iodide 
of  potassium  ; the  precipitate  is  once  more  redissolved. 

Note. — When  first  precipitated,  mercuric  iodide  is  yellowish-red, 
soon  changes  to  a beautiful  scarlet.  Its  solubility  either  in  solu- 
tion of  the  mercuric  salt  or  in  solution  of  iodide  of  potassium  renders 
the  detection  of  a small  quantity  of  a mercuric  salt  by  iodide  of 
r'  tassium,  or  a small  quantity  of  an  iodide  by  a mercuric  solution, 

icult,  and  hence  lessens  the  value  of  the  reaction  as  a test. 

, Third  Analytical  Reaction. — Add  a solution  of  mercuric 
salt  to  solution  of  ammonia,  taking  care  that  the  mixture, 
after  well  stirring,  still  smells  of  ammonia ; a white  pre- 
cipitate falls. 

Ammoniated  Mercury. 

Performed  in  a test-tube,  this  reaction  is  a very  delicate  test  of 
presence  of  a mercuric  salt ; performed  in  larger  vessels,  the 
uric  salt  being  corrosive  sublimate  (3  ounces  dissolved  in  3 pints 
4iHed  water,  the  solution  poured  into  4 fluidounces  of  Solution 
mmonia,  and  the  precipitate  washed  and  dried  over  a water- 
it  is  the  usual  process  for  the  preparation  of  ‘‘  white  precipi- 
the  old  “ ammonio-chloride,”  or  “ amido-chloride  of  mercury,” 
now  i^nown  as  Ammoniated  Mercury  [Hydrargyrum  Ammoniatum^ 
B.  P.,  and  U.  S.  P.). 

Constitution  of  Ammoniated  Mercury. — This  precipitate  is  con- 
sidered to  be  the  chloride  of  mercuric  ammonium  (NH2Hg"Cl) — 
that  is,  chloride  of  ammonium  (NH^Cl)  in  which  two  atoms  of  univa- 
lent hydrogen  are  replaced  by  one  bivalent  atom  of  mercury. 

HgClj  + 2NH,HO  = NH2Hg"Cl  + NH,C1  + 2H2O 

Mercuric  Ammonia.  “White  Chloride  of  Water, 

chloride.  precipitate.”  ammonium. 

Varieties  of  Ammoniated  Mercury. — If  the  order  of  mixing  be 
reversed  and  ammonia  be  added  to  solution  of  mercuric  chloride, 
a double  chloride  of  mercuric-ammonium  and  mercury  results 
(NH2HgCl,  HgCl2) : it  contains  76.55  per  cent,  of  mercury.  Pre- 
viously to  the  year  1826,  “ white  precipitate”  was  officially  made  by 
adding  a fixed  alkali  to  a solution  of  equal  parts  of  corrosive  subli- 
mate and  sal-ammoniac;  this  gave  a double  chloride  of  mercuric- 
ammonium  and  ammonium  (NH2Hg01,NH401),  containing  65.57  per 
cent,  of  mercury.  This  compound  is  now  knowm  as  wffiite 

precipitate,”  because  at  a temperature  somewhat  below  redness  it 
fuses  and  then  volatilizes.  The  white  precipitate”  which  has  been 
16 


182 


THE  METALLIC  RADICALS. 


official  since  1826  contains  79.52  per  cent,  of  mercury.  The  true 
compound  may  be  distinguished  as  “ inf  usihle  white  precipitate,” 
from  the  fact  that  when  heated  it  volatilises  without  fusing.  An  oint- 
ment of  this  body  is  official  ( Uyiguentum  Hydra%gyri  Ammoniati, 
B.  P.  and  U.  S.  P.).  Prolonged  w^ashing  with  w’ater  converts 
“white  precipitate”  into  a yellowish  compound  (NH2HgCl, HgO) ; 
hence  the  official  preparation  is  seldom  thoroughly  freed  from  the 
chloride  of  ammonium  wffiich  is  formed  during  its  manufacture,  and 
which,  if  present  in  larger  proportion  than  seven  or  eight  per  cent., 
gives  to  it  the  character  of  partial  or  complete  fusibility. 

Note. — Chloride  of  mercuric  ammonium  is  only  one  member  of  a 
large  class  of  similar  compounds,  derivable  from  the  various  salts  of 
ammonium  by  displacement  of  atoms  of  hydrogen  by  other  atoms. 
The  composition  of  ammonio-nitrate  of  silver  and  ammonio-sulphate 
of  copper,  made  without  excess  of  ammonia  (p.  153),  is  consistent 
with  this  vie^v. 


r HI 

n]  H [ci 

l H ] 


Chlpvide  of 
ammonium. 


N 


Hg" 


H 

H 


Cl 


Chloride  of 
mercuric 
ammonium. 


r Ag  1 

[no, 

I ^ I 


Nitrate  of 
argent-arn  rnon- 
ammonium. 


N, 


r cu"  1 

I 1 


I 


H 

ih;  j 

Sulphate  of 
cup  r-a  mm  on- 
ammonium. 


SO, 


The  composition  of  the  crystals  of  ammonio-sulphate  of  copper  (p. 
169)  is  consistent  with  the  second  of  the  following  formulae,  the  first 
being  that  of  sulphate  of  ammonium  : — 


N, 


r H,i 
^ i so, 

I -*^2  I 

I H^  J 


N, 


Cu"  1 
Am-  ! 


1-  so. 


IH,  J 


Fourth  Analytical  Reaction, — Pass  sulphuretted  hydro- 
gen through  a mercuric  solution  ; a black  precipitate  of 
mercuric  sulphide  (HgS)  falls. 


Note. — Sulphuretted  hydrogen  also  precipitates  mercurous  sul- 
phide (Hg2S)  from  mercurous  solutions ; and  in  appearance  the  pre- 
cipitates are  alike ; hence  this  reagent  does  not  distinguish  between 
mercurous  and  mercuric  salts.  But  in  the  course  of  systematic 
analysis,  mercuric  salts  are  thrown  down  from  solution  as  sulphide 
after  mercurous  salts  have  been  otherwise  removed.  The  sulphides 
are  insoluble  in  sulphydrate  of  ammonium. 

Note. — An  insufficient  amount  of  the  gas  gives  a wffiite  or  colored 
precipitate  of  ox^^sulphide. 

Ftliiops  Mineral,  the  Hydrargyri  Sidphuretum  cum  Sulphur e, 
is  a mixture  of  sulphide  of  mercury  and  sulphur,  obtained  on  tritu- 
rating the  elements  in  a mortar  till  globules  are  no  longer  visible. 
Its  name  is  probably  in  allusion  to  its  similarity  in  color  to  the  skin 
of  the  Ethiop.  It  was  formerly  official. 

Vermilion  is  mercuric  sulphide  prepared  by  heating  together  sul- 
phur and  mercury,  and  subliming  the  mixture  [Hydrargyri  Sidphu- 
return  Ruhrnm,  U.  S.  P.). 


MERCURY. 


183 


Tests  continued.  (The  mercury  occurring  as  mercurous 
salt.) 

Fifth  Analytical  Reaction. — To  a solution  of  a mercurous 
salt  (the  mercurous  nitrate  obtained  in  the  second  syn- 
thetical reaction,  for  example)  add  hydrochloric  acid,  or 
any  soluble  chloride ; a white  precipitate  of  calomel  (HgCl) 
occurs. 

This  reaction  was  formerly  official  in  the  Dublin  Phar- 
macopoeia as  a process  for  the  preparation  of  calomel. 

Sixth  Analytical  Reaction. — To  solution  of  a mercurous 
salt  add  iodide  of  potassium  ; green  mercurous  iodide 
(Hgl)  is  precipitated. 

Seventh  Analytical  Reaction. — To  a mercurous  salt,  dis- 
solved or  undissolved  (calomel),  add  ammonia;  black  salt 
(chloride)  of  mercurous  ammonium  (NH^Hg^Cl)  is  formed. 

Other  tests  for  Mercury. 

The  elimination  of  mercury  in  the  actual  state  of  metal 
by  the  copper  test,  coupled  with  the  production  or  non- 
production of  a white  precipitate  on  the  addition  of  hydro- 
chloric acid  to  the  original  solution,  is  usually  sufficient 
evidence  of  the  presence  of  mercury  and  its  existence  as  a 
mercurous  or  mercuric  salt.  But  other  tests  may  some- 
times be  applied  with  advantage.  Thus,  metallic  mercury 
is  deposited  on  placing  a drop  of  the  solution  on  a plate  of 
gold  (sovereign  or  half  sovereign),  and  touching  the  drop 
and  the  edge  of  the  plate  simultaneously  with  a key;  an 
electric  current  passes,  under  these  circumstances,  from  the 
gold  to  the  key,  and  thence  through  the  liquid  to  the  gold, 
decomposing  the  salt,  the  mercury  of  which  forms  a white 
metallic  spot  on  the  gold,  while  the  other  elements  go  to 
the  iron.  This  is  called  the  galvanic  test.^  and  is  useful  for 

clinical  purposes. Solution  of  stannous  chloride  (SnCl2) 

— see  Index — from  the  readiness  with  which  it  forms  stannic 
salts  (SnCl^,  Sn02,  etc.),  gives  a white  precipitate  of  mercu- 
rous chloride  in  mercuric  solutions,  and  quickly  still  further 
reduces  this  mercurous  chloride  (and  other  mercury-salts) 
to  a grayish  mass  of  finely  divided  mercury  ; this  is  the  old 
magpie  test.,  probably  so  called  from  the  white  and  gray 
appearance  of  the  precipitate.  The  reaction  may  even  be 
obtained  from  such  insoluble  mercury  compounds  as  “ white 
precipitate.’^ Confirmatory  tests  for  mercuric  and  mer- 

curous salts  will  be  found  in.  the  action  of  solution  of  pot- 


184 


THE  METALLIC  RADICALS. 


ash,  solution  of  soda, lime-water,  solution  of  ammonia,  and 
solution  of  iodide  of  potassium.  {Vide  pages  180  to  183.) 
Xormal  alkaline  carbonates  produce  3^ellowish  mercu- 
rous carbonate,  and  brownish-red  mercuric  carbonate,  both 

of  them  unstable. Alkaline  bicarbonates  give  mercurous 

carbonate  and  white  (soon  becoming  red)  mercuric  oxysalt. 

Yellow  chromate  of  potassium  (K2CrOj  gives,  with 

mercurous  salts,  a red  precipitate  of  mercurous  chromate 

(Hg^CrO^). Mercuiy  and  all  its  compounds  are  volatile, 

subliming  unchanged  by  heat:  the  experiment  is  most  con- 
veniently performed  in  a test-tube. 

Antidote. — Albumen  gives  a white  precipitate  with  solu- 
tion of  mercuric  salts  ; hence  the  importance  of  administer- 
ing white  of  egg  while  waiting  for  a stomach-pump  in  case 
of  poisoning  b}^  corrosive  sublimate. 


QUESTIONS  AND  EXEECJSES. 

293.  Name  the  chief  ore  of  mercury,  and  describe  a process  for 
the  extraction  of  the  metal. 

294.  Give  the  properties  of  mercury. 

295.  In  what  state  does  mercury  exist  in  ‘‘  Gray  Powder  ?” 

296.  What  other  preparations  of  metallic  mercury  itself  are  em- 
ployed in  medicine  ? 

297.  State  the  relation  of  the  mercurous  to  the  mercuric  com- 
pounds. 

298.  Distinguish  between  an  alloy  and  an  amalgam. 

299.  State  the  formulae  of  the  two  Iodides  of  Mercury. 

300.  Under  what  circumstances  does  mercuric  iodide  assume  tw'o 
different  colors  ? 

301.  Illustrate  the  chemical  law  of  Multiple  Proportions  as  ex- 
plained by  the  atomic  theory,  employing  for  that  purpose  the  stated 
composition  of  the  two  iodides  of  mercury. 

302.  Write  down  the  formulae  of  Mercurous  and  Mercuric  Nitrates 
and  Sulphates. 

303.  How  is  Mercuric  Sulphate  prepared 

304.  What  is  the  formula  of  “ Turpeth  MineraW^ 

305.  Describe  the  processes  necessary  for  the  convertion  of  mercury 
into  Calomel  and  Corrosive  Sublimate,  using  diagrams. 

306.  Why  is  black  oxide  of  manganese  sometimes  mixed  wdth  the 
other  ingredients  in  the  preparation  of  corrosive  sublimate  ? 

307.  Give  the  chemical  and  physical  points  of  difference  betw^een 
calomel  and  corrosive  sublimate. 

308.  How  may  a small  quantity  of  calomel  in  corrosive  sublimate 
be  detected  ? 

309.  Work  out  a sum  showing  how  much  mercury  wdll  be  required 
in  the  manufacture  of  one  ton  of  Calomel.  Ans.  17  cw4.  nearly. 


LEAD. 


185 


310.  Mention  official  preparations  of  the  chlorides  of  mercury. 

311.  Give  the  formulae  and  mode  of  formation  of  the  Red,  Yellow, 
and  Black  Oxides  of  Mercury,  employing  diagrams. 

312.  Explain  the  action  of  the  chief  general  test  for  mercury. 

313.  How  are  mercurous  and  mercuric  salts  analytically  distin- 
guished ? 

314.  Give  a probable  view  of  the  constitution  of  Hydrargyrum 
Ammonzatum,  and  an  equation  showing  how  it  is  made. 

315.  What  is  the  best  temporary  antidote  in  cases  of  poisoning  by 
mercury  ? 


LEAD. 

Symbol  Pb.  Atomic  weight  207. 

Source. — The  ores  of  lead  are  numerous ; but  the  one  from  which 
the  metal  is  chiefly  obtained  is  the  sulphide  of  lead  (PbS),  or  galena 
(from  galene,  tranquillity,  perhaps  from  its  supposed  effect  in 

allaying  pain). 

Preparation. — The  ore  is  first  roasted  in  a current  of  air ; much 
sulphur  is  thus  burnt  off  as  sulphurous  acid  gas,  while  some  of  the 
metal  is  converted  into  oxide  and  a portion  of  the  sulphide  oxidized 
to  sulphate.  Oxidation  being  stopped  when  the  mass  presents  cer- 
tain appearances,  the  temperature  is  raised,  and  the  oxide  and  sul- 
phate, reacting  on  undecomposed  sulphide,  yield  the  metal  and  much 
sulphurous  acid  gas  : — 

2PbO  + PbS  = Pb3  + SO, 

PbSO,  + PbS  = Pb,  + 2SO,. 

Uses. — The  uses  of  lead  are  well  known.  Alloyed  with  arsenicum 
it  forms  common  shot,  with  antimony  gives  type-metal,  with  tin  sol- 
der, and  in  smaller  quantities  enters  into  the  composition  of  Britan- 
nia metal,  peiuter,  and  other  alloys. 

The  salts  of  lead  used  in  pharmacy  and  all  other  preparations  of 
lead  are  obtained,  directly  or  indirectly,  from  the  metal  itself.  Heated 
in  a current  of  air,  lead  combines  with  oxygen  and  forms  oxide  of 
lead  (PbO)  {Plumhi  Oxidum,  B.  P.  and  U.  S.  P.),  a yellow  powder 
[massicot),  or,  if  fused  and  solidified,  a brighter  reddish-yellow  heavy 
mass  of  brighiscalesAermed  litharge  (from  lithos,  a stone,  and 
apyupo^,  It  is  from  this  oxide  that  the  chief  lead 

compoundsaW^btained.  Oxide  of  lead,  by  further  roasting  in  a 
current  of  air,  yields  red  lead  (or  minium),  Pb^O^,  or  Pb022Pb0. 
Both  oxides  are  much  used  by  painters,  paper-stainers,  and  glass- 
manufacturers.  White  lead  is  a mixture  of  carbonate  (PbCOg)  and 
hydrate  of  lead  (Pb2HO)  (commonly  2 molecules  of  the  former  to  1 
of  the  latter),  usually  ground  up  with  about  7 per  cent,  of  linseed 
oil ; it  is  made  by  exposing  lead,  cast  in  spirals  or  little  gratings,  to 
the  action  of  air,  acetic  fumes,  and  carbonic  acid,  the  latter  generated 
from  decaying  vegetable  matter,  such  as  spent  tan  ; oxy acetate  of 
lead  slowly  -but  continuously  forms,  and  is  as  continuously  decom- 
posed by  the  carbonic  acid  with  production  of  hydrate  and  carbonate, 

16* 


186 


THE  METALLIC  RADICALS. 


or  dry  white  lead.  The  grating-like  masses,  when  ground,  form  the 
heavy  white  pulverulent  off.cial  Plumhi  Carhonas,  B.  B.  and  U.  S. 
P.  The  latter  is  the  active  constituent  of  JJnguentum  Plumhi  Car- 
bonatis,  B.  P.  and  U.  S.  P.,  the  old  Unguentum  Cerussce. 

Lead  compounds  are  poisonous,  producing  saturnine  colic,  or 
even  paralysis.  These  effects  are  termed  saturnine  from  an  old  name 
of  lead,  Saturn.  The  alchemists  called  lead  Saturn,  first,  because 
they  thought  it  the  oldest  of  the  seven  then  known  metals,  and  it 
might  therefore  be  compared  to  Saturn,  who  was  supposed  to  be  the 
father  of  the  gods ; and,  secondly,  because  its  power  of  dissolving 
other  metals  recalled  a peculiarity  of  Saturn,  who  was  said  to  be  in 
the  habit  of  devouring  his  own  children. 

Quantivalence.  — The  atom  of  lead  is  sometimes  quadrivalent 
(Pb"") ; but  in  most  of  the  compounds  used  in  medicine  it  exerts 
bivalent  activity  only  (Pb"). 

Reactions  having  {a)  Synthetical  and  (h)  Analytical 
Interest. 

(a)  Synthetical  Reactions. 

Acetate  of  Lead. 

First  Synthetical  Reaction. — Place  a few  grains  of  oxide 
of  lead  in  a test-tube,  add  about  an  equal  weight  of  water 
and  two  and  a half  times  its  weight  of  acetic  acid,  and  boil ; 
the  oxide  dissolves  and  forms  a solution  of  acetate  of  lead 
(Pb2C.^H302).  When  cold,  or  on  evaporation  (the  solu- 
tion being  kept  faintly  acid),  crystals  of  acetate  of  lead 
(Pb2C2H302,  3H2O)  are  deposited.  Larger  quantities  are 
obtained  b}^  the  same  method. 

PbO  -f  2HC2H3O2  = Pb2C2H302  + H2O 

Oxide  of  lead.  Acetic  acid.  Acetate  of  lead.  Water. 

This  is  the  official  process  for  Plumhi  Acetas,  B.  B.  and  U.  S.  P. 
The  salt  is  vulgarly  termed  Sugar  of  Lead,  from  its  sweet  taste. 
Besides  its  direct  use  in  Pharmacy,  it  forms  three-fourths  of  the 
Pihda  Plumhi  cum  Opio,  B.  P.,  is  the  chief  constituent  of  Unguen- 
tum Plumhi  Acetatis,  B.  P.,  and  an  ingredient  in  Suppositoria 
Plumhi  Composita,  B.  P.,  and  Suppositoria  Plumhi  and  Supposi- 
toria Plumhi  et  Opii,  U.  S.  P. 


Subacetate  or  Oxyacetate  of  Lead. 

Second  Synthetical  Reaction. — Boil  acetate  of  lead  with 
about  four  times  its  weight  of  water,  and  rather  more  than 
two-thirds  its  weight  of  oxide  of  lead  ; the  resulting  filtered 
liquid  is  solution  of  oxyacetate  of  lead,  Liquor  Plumhi 
Suhacefafis,  B.  P,  and  U.  S.  P, 


LEAD. 


18t 


The  official  (B.  P.)  Liquor  is  made  by  boiling  5 ounces  of  ace- 
tate and  3^  of  oxide  in  1 pint  of  distilled  water  for  half  an  hour 
(constantly  stirring),  filtering,  and  making  up  for  any  loss  by  evapo- 
ration by  diluting  the  filtrate  to  1 pint. 

A similar  solution  was  used  by  M.  Goulard,  who  called  it  Extrac- 
tum  Saturni,  and  drew  attention  to  it  in  1770.  It  is  now  frequently 
termed  Goulard’s  Extract.  A more  dilute  solution,  1 of  Liquor 
and  1 of  spirit  in  80  of  distilled  water,  is  also  official  in  the  Pharma- 
copoeias, under  the  name  of  Liquor  Plumbi  Subacetatis  Dilutus. 
The  latter  is  commonly  known  as  Goulard  Water.  The  stronger 
solution  is  the  chief  ingredient  in  Unguentum  Plumbi  Subacetatis 
Compositum,  B.  P.,  a slight  modification  of  the  old  Goulard's 
Cerate.  Similar  preparations  are  official  in  the  United  States  Phar- 
macopoeia. 

Oxyacetates  of  Lead. — The  official  subacetate  of  lead  is  not  a 
definite  chemical  salt.  It  is  probably  a mixture  of  two  subacetates 
of  lead,  which  are  well-known  crystalline  compounds,  and  which  the 
author  is  disposed  to  regard  as  having  a constitution  similar  to  that 
he  has  already  indicated  for  some  other  salts  (see  Iron,  Antimony, 
and  Bismuth).  Exposed  to  air  it  absorbs  carbonic  acid  gas,  and 
hydrato-carbonate  of  lead  is  deposited. 

Acetate  of  Lead  (3  molecules)  . . . Pbg  6C2H3OJ 

B p f Pyro-oxyacetate  of  lead Pb30402H302 

' \ Goulard’s  oxyacetate  of  lead  ....  Pb30  22  C2H302 
Oxide  of  lead  (3  molecules) Pb303. 

PbO  -h  Pb2C2H302  = Pb202C2H302 

Oxide  of  Acetate  of  Official  “subacetate.” 

lead.  lead. 

or  3PbO  + 3(Pb2C,H,02)  = Pb3040,H302  + Pb,0,2C2Hs0, 

Oxide  of  Acetate  of  Pyro-oxyacetate,  Goulard’s  oxyacetate. 

lead.  lead.  Tbe  official  “ subacetate.” 

Nitrate  of  Lead.  Eed  Lead.  Peroxide  of  Lead. 

Third  Synthetical  Beaction, — Digest  a few  grains  of  red 
lead  in  nitric  acid  and  water ; nitrate  of  lead  (Pb2N  O3)  is 
formed,  and  remains  in  solution,  while  a puce  colored  per- 
oxide of  lead  (PbO^)  is  precipitated. 

Nitrate  of  Lead  {Plumbi  Nitras,  B.  P.  and  U.  S.  P.)  is  more 
directly  made  by  dissolving  litharge  (PbO)  in  nitric  acid;  but  the 
above  reaction  serves  to  bring  before  the  reader  two  other  oxides  of 
lead,  namely,  red  lead  (Pb304)  and  peroxide  of  lead  (Pb02).  In  the 
latter  oxide  the  quadrivalent  character  of  lead  is  obvious.  Nitrate 
of  lead  is  used  officially  in  preparing  iodide  of  lead  ; for  this  purpose 
the  above  mixture  is  filtered,  the  precipitate  of  peroxide  of  lead 
purified  from  adhering  nitrate  by  passing  hot  water  through  the 
filter,  the  filtrate  and  washings  evaporated  to  dryness  to  remove 
excess  of  nitric  acid,  the  residual  nitrate  of  lead  redissolved  by  ebul- 
lition with  a small  quantity  of  hot  water,  and  the  solution  set  aside 
to  crystallize,  or  a portion  at  once  used  for  the  following  experiment. 
Nitrate  of  lead  forms  white  crystals  derived  from  octahedra. 


188 


THE  METALLIC  RADICALS. 


Iodide  of  Lead. 

Fourth  Synthetical  Reaction. — To  a neutral  solution  of 
nitrate  of  lead  add  solution  of  iodide  of  potassium  ; a pre- 
cipitate of  iodide  of  lead  (Pblj)  falls  {Plumhi  lodidum^ 
B.  P.  and  U.  S.  P.).  Equal  weights  of  the  salts  may  be 
used  in  making  large  quantities. 

Pb2N03  -f  2KI  = Pbl,  4-  2KNO3 

Nitrate  of  Iodide  of  Iodide  of^  Nitrate  of 

lead.  potassium.  lead.  potassium. 

Iodide  of  lead  is  the  chief  ingredient  in  Emplastrum  Plumhi 
lodidi,  B.  P.,  and  Unguentum  Plumhi  lodidi,  B.  P.  and  U.  S.  P. 

Crystals  of  Iodide  of  Lead. — Heat  the  iodide  of  lead 
with  the  supernatant  liquid,  and,  if  necessary,  filter ; the 
salt  is  dissolved,  and  again  separates  in  golden  crystalline 
scales  as  the  solution  cools. 

Oleate  of  Lead  (Lead  Plaster). 

Fifth  Synthetical  Reaction. — >Boil  together  in  a small 
dish  some  very  finely-powdered  oxide  of  lead,  with  about 
twice  its  weight  of  olive  oil,  and  ten  or  twenty  times  as 
much  water,  well  stirring  the  mixture,  and  from  time  to 
time  replacing  water  that  lias  evaporated ; the  product  is  a 
white  mass  of  oleate  of  lead  (Pb2Cj3H3302)  {Emplastrum 
Plumhi.^  B.  P.  and  U.  S.  P.),  glycerine  remaining  in  solu- 
tion in  the  water.  Larger  quantities  are  prepared  in  the 
same  manner. 

3PbO  + 3H,0  + 2(C3H,3C,,H330,) 

Oxide  of  Water.  Oleate  of  glyceryl 

lead.  (olive-oil  or  oleine). 

2(C3H33H0) 

Hydrate  of  glyceryl 
(glycerine). 

The  action  between  the  oxide  of  lead  and  olive  oil  is  slow,  requir- 
ing several  hours  for  its  completion. 

The  glycerine  rudiy  be  obtained  by  treating  the  aqueous  product 
of  tlie  above  reaction  with  sulphuretted  hydrogen  to  remove  a trace 
of  lead,  then  digesting  with  animal  charcoal,  filtering  and  evapo- 
rating. But  on  the  large  scale  glycerine  is  now  usually  produced  as 
a by-product  in  the  manufacture  Of  candles  ; for  its  elements  are  found 
in  all  vegetable  and  animal  fats.  ( Vide  Index.) 


^ 3(Pb2C.3H3,,03) 
Oleate  of  lead 
(lead  plaster). 


Modes  of  forming  chloride^  stdphide,  chromate,  sulphate,  hy- 
drate,  and  other  salts  of  lead  are  incidentally  described  in  the  follow- 
ing analytical  paragraphs. 


LEAD. 


189 


(b)  Reactions  having  Analytical  Interest  {Tests). 

First  Analytical  Reaction. — To  a solution  of  lead  salt 
(acetate,  for  example)  add  hydrochloric  acid  ; a white  pre- 
cipitate of  chloride  of  lead  (PbCl^)  is  obtained.  Boil  the 
precipitate  with  much  Tvater;  it  dissolves,  but,  on  the  so- 
lution cooling,  is  redeposited  in  small  acicular  crystals. 
Filter  the  cold  solution,  and  pass  sulphuretted  hydrogen 
through  it;  a black  precipitate  (sulphide  of  lead,  PbS) 
shows  that  the  chloride  of  lead  is  soluble  to  a slight  extent 
in  cold  water. 

Notei^A.  white  precipitate  on  the  addition  of  hydrochloric  acid, 
soluble  1*0  hot  water,  and  blackened  by  sulphuretted  hydrogen,  suffi- 
ciently distinguishes  lead  salts  from  those  of  other  metals,  but  the 
non-production  of  such  a precipitate  does  not  prove  the  absence  of 
a small  quantity  of  l^d,  chloride  of  lead  being  slightly  soluble  in 
cold  water.  Hydrochloric  acid  will  be  found  to  be  a useful  but  not 
a delicate  test  for  lead. 

Second  Analytical  Reaction. — Through  a dilute  solution 
of  a lead  salt  joass  sulphuretted  hydrogen  ; a black  pre- 
cipitate of  sulphide  of  lead  (PbS)  occurs. 

Lead  in  Water, — The  foregoing  is  a very  delicate  test.  Should  a 
trace  of  lead  be  present  in  water  used  for  drinking-purposes,  sulphu- 
retted hydrogen  will  detect  it.  On  passing  the  gas  through  a pint 
of  such  water,  a brownish  tint,  more  or  less  deep,  is  produced.  If 
the  tint  is  scarcely  perceptible,  set  the  liquid  aside  for  a day  ; the 
gas  will  become  decomposed  and  a thin  layer  of  sulphur  be  found  at 
the  bottom  of  the  vessel,  white  if  no  lead  be  present,  but  more  or 
less  brown  if  it  contain  sulphide  of  lead. 

Third  Analytical  Reaction. — To  solution  of  a lead  salt 
add  sulphydrate  of  ammonium  ; a black  precipitate  of  sul- 
phide of  lead  falls,  insoluble  in  excess. 

Fourth  Analytical  Reaction. — To  solution  of  a lead  salt 
add  solution  of  chromate  of  potassium  (K^CrOJ  ; a yellow 
precipitate  of  chromate  of  lead  (PbCrO^)  is  formed,  inso- 
luble in  weak  acids. 

Chromes. — This  reaction  has  technical  as  well  as  analytical  in- 
terest. The  precipitate  is  the  common  pigment  termed  chrome  yel- 
low, or  lemon  chrome.  Boiled  with  lime  and  water,  a portion  of  the 
chromic  radical  is  removed  as  soluble  chromate  of  calcium,  and  an 
oxychromate  of  lead,  of  a bright  red  or  orange  color  [orange  chrome), 
is  produced. 

Fifth  Analytical  Reaction. — To  solution  of  a lead  salt 
add  dilute  sulphuric  ac.id,  or  solution  of  a sulphate  ; a white 
precipitate  of  sulphate  of  lead  (PbSOJ  falls. 


190 


THE  METALLIC  RADICALS. 


Sulphate  of  lead  is  slightly  soluble  in  strong  acids,  and  in  solu- 
tions of  alkaline  salts  ; it  is  insoluble  in  acetic  acid. 

In  dilute  solutions  this  sulphuric  reaction  does  not  take  place  im- 
mediately ; the  precipitate,  however,  falls  after  a time ; its  appear- 
ance may  be  hastened  by  evaporating  the  solution  nearly  to  dryness 
and  then  rediluting. 

The  white  precipitate  always  noticed  in  the  vessels  in  which 
diluted  sulphuric  acid  is  kept,  is  sulphate  of  lead,  derived  from  the 
leaden  chambers  in  which  the  acid  is  made  ; solubility  in  strong  acid 
and  insolubility  in  weak,  explains  its  appearance. 

Antidotes. — From  the  insolubility  of  sulphate  of  lead  in  water,  the 
best  antidote  in  a case  of  poisoning  by  the  acetate  or  other  soluble 
salt  of  lead,  is  a soluble  sulphate,  such  as  Epsom  salt,  sulphate  of 
sodium  or  alum,  vomiting  being  also  induced,  or  the  stomach-pump 
applied  as  quickly  as  possible. 

Other  tests  for  lead  will  be  found  in  the  reaction  with 
iodide  of  potassium  (vide  p.  188)  ; with  alkaline  carbonates.^ 
a white  precipitate  (2PbC03-t-Pb2H0)  insoluble  in  excess  ; 
with  alkalies.^  a white  precipitate  (Pb2HO)  more  or  less 
soluble  in  excess ; with  alkaline  phosphates.^  arseniates., 
ferrocyanides  and  cyanides.,  precipitates  mostly  insoluble, 
but  of  no  special  analytical  interest.  Insoluble  salts  of 
lead  are  decomposed  by  solutions  of  potash  (KHO)  or  soda 
(NaHO). 

The  metal  is  precipitated  in  a beautifully  crystalline  state 
by  metallic  zinc  and  some  other  metals  ; the  lead  tree  is 

thus  formed. The  blowpipe-flame  decomposes  solid  lead 

compounds  placed  in  a small  cavity  in  a piece  of  charcoal, 
a soft  malleable  bead  of  metal  being  produced,  and  a yel- 
lowish ring  of  oxide  deposited  on  the  charcoal. 


QUESTIONS  AND  EXEPCISES. 

316.  Write  down  equations  descriptive  of  the  smelting  of  galena. 

317.  Mention  some  of  the  alloys  of  lead. 

318.  How  is  litharge  produced  ? 

319.  Give  the  formulm  of  white  lead  and  red  lead. 

320.  Describe  the  manufacture  of  white  lead. 

321.  What  is  the  quantivalence  of  lead  ? 

322.  Draw  a diagram  expressive  of  the  formation  of  Acetate  of 
Lead. 

323.  Describe  the  preparation  and  composition  of  Liquor  Plumbi 
Subacetatis. 

324.  What  is  the  action  of  nitric  acid  on  red  lead,  litharge,  and 
metallic  lead  ? 

325.  How  is  the  official  Iodide  of  Lead  prepared? 


SILVER. 


191 


326.  Describe  the  reaction  between  oxide  of  lead,  water,  and  olive 
'oil,  at  the  temperature  of  boiling  water,  and  give  chemical  formulae 

explanatory  of  the  constitution  of  the  products. 

327.  Mention  the  chief  tests  for  lead. 

328.  How  would  you  search  for  lead  in  potable  water  ? 

329.  What  is  the  composition  of  chrome  yellow  ? 

330.  State  a method  whereby  lead,  barium,  and  silver  may  be 
separated. 

331.  Name  the  best  antidote  in  case  of  poisoning  by  salts  of  lead. 


SILVEK. 

Symbol  Ag.  Atomic  weight  108. 

Source. — This  element  occurs  in  nature  in  the  free  slate  and  as 
ore,  the  common  variety  being  sulphide  of  silver  (Ag.^S)  in  combina- 
tion with  much  sulphide  of  lead,  forming  argentiferous  galena. 

Preigaration. — The  lead  from  galena  (p.  185)  is  melted  and  slowly 
cooled ; crystals  of  lead  separate  and  are  raked  out  from  the  still 
fluid  mass,  and  thus  an  alloy  very  rich  in  silver  is  finally  obtained  : 
this  is  roasted  in  a current  of  air,  whereby  the  lead  is  oxidized  and 
removed  as  litharge,  pure  silver  remaining.  Other  ores  undergo 
various  preparatory  treatments  according  to  their  nature,  and  are 
then  shaken  with  mercury,  which  amalgamates  with  and  dissolves 
the  particles  of  silver,  the  mercury  being  subsequently  removed  from 
the  amalgam  by  distillation.  Soils  and  minerals  containing  metallic 
silver  are  also  treated  in  this  way.  An  important  improvement  in 
the  amalgamation  process,  by  which  the  mercury  more  readily  unites 
with  the  silver,  consists  in  the  addition  of  a small  proportion  of  sodium 
to  the  mercury — a recent  discovery  simultaneously  made  in  England 
by  Crookes,  and  in  New  York  by  Wurtz. 

Reactions  having  {a)  Synthetical  and  ih)  Analytical 
Interest. 

(a)  Synthetical  Reactions, 

Impure  Nitrate  of  Silver. 

First  Synthetical  Reaction, — Dissolve  a silver  coin  in 
nitric  acid;  nitric  oxide  gas  (NO)  and  nitrous  anhydride 
(N2O3)  are  evolved,  and  a solution  of  nitrates  of  silver  and 
copper  obtained. 

Silver  Coinage. — Pure  silver  is  too  soft  for  use  as  coin,  it  is  there- 
fore hardened  by  alloying  with  copper.  The  silver  money  of  England 
contains  7.5,  of  France  10,  and  of  Prussia  25  per  cent,  of  copper. 
One  pound  troy  of  standard  silver  is  coined  into  66  shillings,  of  which 
the  metal  is  worth  from  60s.  to  62s.  according  to  the  market  price  of 
silver.  The  standard  fineness  of  silver  is  0.925,  three  alloy  in  40. 


192 


THE  METALLIC  RADICALS. 


The  fineness  of  the  French  standard  silver  is  0.900  in  the  five-franc 
piece ; but  an  inferior  alloy  of  0.835  is  used  for  the  lower  denomina- 
tions. The  single-franc  piece,  composed  of  the  latter  alloy,  is  still 
made  to  weigh  five  grammes,  the  weight  originally  chosen  for  the 
franc  as  the  unit  of  the  monetary  scale  when  the  fineness  of  the  coin 
was  0.900.  It  has  now  become  a token,  like  the  British  shilling,  of 
which  the  nominal  value  exceeds  the  metallic  value.  British  silver 
coins  are  a legal  tender  in  payments  to  the  amount  of  40s.  only. 

Chloride  of  Silver. 

Second  Synthetical  Reaction — To  the  product  of  the 
above  reaction  add  water  and  h^-drochloric  acid  or  a solu- 
ble chloride  ; white  chloride  of  silver  (AgCl)  is  precipitated, 
copper  still  remaining  in  solution.  Collect  the  precipitate 
on  a filter,  and  wash  with  water ; it  is  pure  chloride  of 
silver. 

Note. — The  nitrates  of  silver  and  copper  may  also  be  separated  by 
evaporating  the  solution  of  the  metals  in  nitric  acid  to  dryness,  and 
gently  heating  the  residue,  when  the  nitrate  of  copper  is  decomposed, 
but  the  nitrate  of  silver  unaffected.  The  latter  may  be  dissolved 
from  the  residual  oxide  of  copper  by  water. 

Chloride  of  silver  may  be  obtained  in  crystals  by  evaporation  of 
its  solution  in  ammonia. 


Pure  Silver. 

Third  Synthetical  Reaction, — Place  the  chloride  of  silver 
of  the  previous  reaction  in  a dish,  wet  it  with  dilute  sul- 
phuric acid,  and  float  a piece  of  sheet  zinc  on  the  mixture; 
metallic  silver  is  precipitated,  and  after  about  one  day 
wholly  removed  from  solution.  Collect  the  precipitate  on  a 
filter  and  wash  with  water ; it  is  pure  metallic  silver,  and 
is  readily  fusible  into  a single  button. 

Note. — Chloride  of  silver  may  also  be  reduced  to  a lump  of  the 
metal  by  fusion,  in  a crucible,  with  about  half  its  weight  of  carbonate 
of  sodium. 


Pure  Nitrate  of  Silver, 

Fourth  Synthetical  Reaction. — Dissolve  the  pure  silver 
of  the  previous  reaction  in  nitric  acid  (3  of  silver  require 
about  2 or  2^  of  strong  acid  diluted  wdth  5 of  water),  and 
remove  excess  of  acid  by  evaporating  the  solution  to  dry- 
ness, slightly  heating  the  residue;  the  product  is  pure 
nitrate  of  silver.  Dissolve  by  heating  with  a small  quan- 
tity of  water;  on  the  solution  cooling,  or  on  evaporation, 
colorless  tabular  crystals  of  nitrate  of  silver  are  obtained.  ^ 

c 


SILVER. 


193 


SAg,  + 8HNO3  = 2N0  + 6AgN03  + 4H,0 

Silver.  Nitric  acid.  Nitric  Nitrate  of  Water. 

oxide.  silver. 

Notes. — The  solution  of  pure  or  refined  silver  [Argentum  Purifi- 
caiitm,  B.  P.,  Argentum  U.  S.  P.)  in  nitric  acid,  evaporation,  and 
crystallization  constitute  the  official  process  for  the  preparation  of 
the  nitrate  [Argenti  Nttras,  B.  P.  and  U.  S.  P.).  The  salt  fused,  and 
poured  into  proper  moulds,  yields  the  white  cylindrical  sticks  or  rods 
[Argenti  Nitras  Fusa,  U.  S.  P.)  commonly  termed  caustic  (from 
»:aJco,  kaio,  I burn),  or  lunar  caustic.  (The  alchemists  called  silver 
Diana  or  Luna,  from  its  supposed  mysterious  connection  with  the 
moon.)  The  specimen  of  nitrate  of  silver  obtained  in  the  above 
reaction,  dissolved  in  water,  will  be  found  useful  as  an  analytical 
reagent.  Nitrate  of  silver  is  soluble  in  rectified  spirit;  but  after  a 
time  reaction  and  decomposition  occur. 

Silver  salts  are  decomposed  when  in  contact  with  organic  matter, 
especially  in  the  presence  of  light  or  heat,  the  metal  itself  being  lib- 
erated, or  a black  insoluble  compound  formed.  Hence  the  value  of 
the  nitrate  in  the  manufacture  of  indelible  ink  for  marking  linen  ; 
hence,  too,  the  reason  of  the  practice  of  rendering  silver  solutions 
clear  by  subsidence  and  decantation,  rather  than  by  filtration  through 
paper ; and  hence  the  cause  of  those  cases  of  actual  combustion  which 
have  been  known  to  occur  in  preparing  pills  containing  oxide  of  silver 
and  essential  oil  or  other  organic  matter. 


Oxide  of  Silver. 

Fifth  Synthetical  Reaction, — To  a few  drops  of  solution 
of  nitrate  of  silver  add  solution  of  potash  or  soda  or  lime- 
water;  an  olive-brown  precipitate  of  oxide  of  silver  (A g.,0) 
occurs.  The  washed  and  dry  oxide,  like  most  silver  com- 
pounds, is  decomposed  by  heat  with  production  of  metal. 

The  Argenti  Oxidum,  B.  P.  and  U.  S.  P.,  is  thus  made,  lime- 
water  (solution  of  potash  U.  S.  P.)  being  the  precipitant  employed, 
soda  and  potash  not  being  so  readily  removed  by  washing.  Three 
and  a half  pints  of  lime-water  will  decompose  half  an  ounce  of  nitrate 
of  silver. 

2AgN03  + Ca2HO  = Ag^O  + Ca2N03  + H,0 

Nitrate  of  Hydrate  of  Oxide  of  Nitrate  of  Water, 

silver.  calcium.  silver.  calcium. 

Methods  of  forming  several  other  salts  of  silver  are  incidentally 
mentioned  in  the  following  analytical  paragraphs. 

(h)  Reactions  having  Analytical  Interest,  ( Tests,) 

First  Analytical  Reaction — To  a solution  of  a silver  salt 
add  hydrochloric  acid  or  other  soluble  chloride ; a white 
curdy  precipitate  of  chloride  of  silver  falls.  Add  nitric 
acid,  and  boil ; the  precipitate  does  not  dissolve.  Pour  off 

n 


194 


THE  >i*ETALLIC  RADICALS. 


the  acid  and  add  solution  of  ammonia;  the  precipitate  dis- 
solves. Neutralize  the  ammoniacal  solution  by  an  acid; 
the  chloride  of  silver  is  re-precipitated. 

This  is  the  most  characteristic  test  for  silver.  The  precipitated 
chloride  is  also  soluble  in  solutions  of  hyposulphite  of  sodium  or  cy- 
anide of  potassium — facts  of  considerable  importance  in  photo- 
graphic operations. 

Other  analytical  reagents  than  the  above  are  occasionally 
useful. ^Sulphuretted  hydrogen,  or  sulphydrate  of  am- 

monium, gives  a black  precipitate,  sulphide  of  silver  ( Ag.^S), 

insoluble  in  alkalies. Solutions  of  potash  or  soda  give 

a brown  precipitate,  oxide  of  silver  (Ag.^0),  converted  into 
a fulminating  compound  by  prolonged  contact  with  am- 
monia.  Phosphate  of  sodium  gives  a jiale  yellow  pre- 

cipitate, phosphate  of  silver  (Ag.jPOj,  soluble  in  nitric 

acid  and  in  ammonia. ^Arseniate  of  ammonium  gives  a 

chocolate-colored  precipitate,  arseniate  of  silver  (AggAsOj, 

already  noticed  in  connection  with  arsenic  acid. ^Iodide 

or  bromide  of  potassium  gives  a yellowish-white  precipitate, 
iodide  or  bromide  of  silver  (Agl  or  AgBr),  insoluble  in 

acids  and  only  slightly  soluble  in  ammonia. -Cy^anide  of 

potassium  gives  a white  precipitate,  cyanide  of  silver 
(AgCy),  soluble  in  excess,  sparingly  soluble  in  ammonia, 
insoluble  in  dilute  nitric  acid,  soluble  in  boiling  concen- 
trated nitric  acid.  Ar genii  cyanidum^  U.  S.  P.,  is  made  by 
distilling  a mixture  of  ferrocyanide  of  potassium  and  di- 
luted sulphuric  acid,  and  passing  the  resijjting  hy^drocy’anic 
acid  into  a solution  of  nitrate  of  silver : HCy  -f  AgNOj  = 
AgCy  -f  HNO3  (the  precipitate  is  well  washed  and  dried). 

Yellow  chromate  of  potassium  (K2CrO^)  gives  a red 

precipitate,  chromate  of  silver  (Ag.^CrOJ. Red  chro- 

mate of  potassium  also  gives  a red  precipitate,  acid  chro- 
mate of  silver  (Ag2Cr04,Cr03). Many  organic  acids 

afford  insoluble  salts  of  silver. Several  metals  displace 

silver  from  solution,  mercury  forming  in  this  way  a ciys- 
talline  compound  known  as  the  silver  tree,  or  Arbor  Dianee. 
— ^In  the  blowpipe  flame,  silver  salts,  placed  on  charcoal 
with  a little  carbonate  of  sodium,  yield  bright  globules  of 
metal  accompanied  by  no  incrustation  as  in  the  corres- 
ponding reaction  with  lead  salts ; the  experiment  may  be 
performed  with  the  nitrate,  which  first  melts  and  then,  like 
all  nitrates,  deflagrates,  yielding  a white  metallic  coating 
of  silver  which  slowly^  aggregates  to  a button. 


COPPER,  MERCURY,  LEAD,  SILVER. 


195 


Antidotes. — Solution  of  common  salt,  sal-ammoniac,  or  any  other 
inert  chloride  should  obviously  be  administered  where  large  doses  of 
nitrate  of  silver  have  been  swallowed.  A quantity  of  sea-water  or 
brine  would  convert  the  silver  into  insoluble  chloride,  and  at  the  same 
time  produce  vomiting. 


QUESTIONS  AND  EXERCISES. 

332.  By  what  process  is  silver  obtained  from  argentiferous  galena  ? 

333.  What  weight  of  English  silver  coin  will  yield  one  pound  of 
pure  nitrate  of  silver  ? 

334.  How  may  the  metal  be  recovered  from  an  impure  mixture  of 
silver  salts  ? 

335.  Give  a diagram  showing  the  formation  of  nitrate  of  silver 
from  the  metal. 

336.  Describe  the  reaction  of  lime  water  and  nitrate  of  silver. 

337.  Mention  the  chief  test  for  silver,  and  the  precautions  to  be 
observed  in  order  that  silver  salts  may  be  distinguished  from  those 
of  lead  and  mercury. 

338.  Name  the  antidote  for  silver. 


DIRECTIONS  FOR  APPLYING  SOME  OF  THE  FOREGOING  REACTIONS 

TO  THE  ANALYSIS  OF  AN  AQUEOUS  SOLUTION  OF  SALTS 

OF  OJSTE  OF  THE  METALS,  CoPPER,  MeRCURY  (EITHER  AS 

MERCUROUS  OR  MERCURIC  SALT),  LeAD,  SiLVER. 

Add  hydrochloric  acid  : — 

Silver  is  indicated  by  a white  curdy  precipitate,  solu- 
ble in  ammonia. 

Mercurous  salts  also  by  a white  precipitate,  turned 
black  by  ammonia. 

Lead  by  a white  precipitate,  insoluble  in  ammonia. 
Confirm  by  boiling  another  portion  of  the  hydro- 
chloric precipitate  in  water  ; it  dissolves. 

If  hydrochloric  acid  gives  no  precipitate,  silver  and  mer- 
curous salts  are  absent.  Lead  can  only  be  present  in  very 
small  quantity.  Mercuric  salts  may  be  present.  Copper 
may  be  present.  Divide  the  liquid  into  three  portions, 
and  apply  a direct  test  for  each  metal. 

Lead  is  best  detected  bj^  the  sulphuric  test ; the  tube 
being  set  aside  for  a time  if  the  precipitate  does 
not  appear  at  once. 

Mercury  is  best  detected  by  the  copper  test.  If  present, 
it  occurs  as  mercuric  salt. 


196 


THE  METALLIC  RADICALS. 


Copper  betrays  itsel^^y  the  blue  color  of  the  liquid 
under  exanpuation.  Confirm  by  the  ammonia 
test.  ^ 

If  the  above  reactions  are  not  thoroughly  conclusive, 
confirmatory  evidence  should  be  obtained  by  the  applica- 
tion of  some  of  the  other  reagents  for  copper,  mercury, 
lead  or  silver. 



Table  of  short  directions  for  applying  ^IfE^op  the  ^ 

FOREGOING  REACTIONS  TO  THE  ANALYSIS  OF  AN  SSl^EOUS  ^ 
SOLUTION  OF  SALTS  OF  ANY  OR  ALL  OF  THE  METALS  COP- 
PER, Mercury  (either  merqurous^r  mercuric  salt, 

OR  both).  Lead,  Silver. 

Add  hydrochloric  acid,  filter,  and  wash  the  precipitate  with  a 
small  quantity  of  cold  water. 


Ppt. 

Pb  Hg(ous)  Ag^ 

Wash  with  boiling  water.  - ^ 

^ Filtrate 

Cu  Hg(ic)  Pb. 
Divide  into  three  portions. 
Test  for 

Ppt. 

Hg(ous)  Ag 

Add  Am  HO. 

Filtrate 

Pb. 

Add  H,SO„ 
white  ppt.* 

Cu  by  AmHO;  blue  sol. 
Hg  (mercuric)  by  Cu; 
globules. 

Pb  by  H2S0^;  white  ppt* 

Precipitate 

Hg 

(mercurous) 

black. 

Filtrate 

Ag. 

Add  HNO3, 
white  ppt. 

* Liquids  containing  only  a small  quantity  of  lead  do  not  readily 
yield  sulphate  of  lead  on  the  addition  of  sulphuric  acid.  Before  lead 
can  be  said  to  be  absent,  therefore,  the  liquid  should  be  evaporated 
to  dryness  with  one  drop  of  sulphuric  acid,  and  the  residue  digested 
in  water;  any  sulphate  of  lead  then  remains  as  a heavy  white  in- 
soluble powder. 


ELEMENTS  HITHERTO  CONSIDERED. 


CHART  FOR  ONE  COMMON  MET 


19T 


Hi 

CQ 

Pi 

s 

P3 

O 


M ^ 


ra 

bD 

p 


biO 

6 

w 


' bD^  P 

.o  %ai 

e bS  ^ be  ^ 

cB  a bjoxj  S US  bcx>  ':S  ^ 

S.22 


‘p.  ® 
p 


be  . 


4^  P^ 


G 

^ Q^.S 

fl  .P  rrt 


• <3^ 

> . %->  Xi 

i ns  P<pL| 

■ ^ CO  CP  M 

g ^ o . • 5yo  oj 

J pH  Phq  S I S “ 

bc^  be  .^2  ^ 
piH  ^ g 

J 

n* 


1 g o 

05  W ^ ^ 

.-s  ® ® •'S  aj 

S.>J  P-S 

ii  o o t-'g  P 

p,-- 

feSH 
2^  -e  3 
o § o 

g •"  a fee  i -g 

to  r\  S-i  hrl 

c3  ^ cs  Ph  ce  W 


in  excess. 

Zn,  white  ppt.  soluble  in 
excess. 


198  THE  METALLIC  RADICALS. 


The  group-tests  of  this  Table  4^’®  HCl,  HjS,  NH4HS,  and  (NH4)2C03. 


COMMON  METALLIC  RADICALS. 


199 


OUTLINE  OF  THE  PRECEDING  TABLES. 


II  Cl 

H^S 

Am  IIS  Am.^CO.^ 

Am.^HAsO^ 

Hg 

Cu  ' 

d 

Zn 

Ba 

Mg 

K 

(as  mercurous 

Hg 

(as  mer- 

salt) 

Pb 

® 05 

' ^ s 

A1 

Ca 

Na 

curic  salt) 

Ag 

Pb  ^ 

d 

Fe 

Am 

As 

d 

aj  05 

Sb 

' d a 

c < 

05 

The  practical  student  should  examine  solutions  containing  the 
above  metals  until  he  is  able  to  analyze  with  facility  and  accuracy. 
In  this  way  he  will  best  perceive  the  peculiarities  of  each  element 
and  their  general  relations  to  each  other.  As  the  rarer  metals  are 
not  included  here,  the  tables  are  not  complete  analytical  schemes  ; 
further  remarks  concerning  them,  therefore,  are  for  the  present 
deferred. 


QUESTIONS  AND  EXERCISES. 

339.  Give  processes  for  the  qualitative  analysis  of  liquids  contain- 
ing the  following  substances  : — 

a.  Antimony  and  Mercurous  salt. 

h.  Lead  and  Calcium. 

c.  Silver  and  Mercurous  salt. 
cl.  Lead  and  Mercuric  salt, 
e.  Copper  and  Arsenicum. 

/.  Arsenicum  and  Antimony. 
g.  Aluminium  and  Zinc. 
li.  Iron  and  Copper. 

i.  Magnesium,  Calcium,  and  Potassium. 

j.  Silver,  Antimony,  Zinc,  Barium,  and  Ammonium. 

340.  Enumerate  the  so-called  group-tests. 

341.  Give  a general  sketch  of  the  method  of  analyzing  a solution 
suspected  to  contain  two  or  more  salts  of  common  metals. 

342.  Classify  the  common  metals  according  to  their  analytical 
relations. 


200 


RARER  METALLIC  RADICALS. 


METALS  OF  MINOR  PHARMACEUTICAL 
IMPORTANCE. 

Thus  far  has  been  considered,  somewhat  in  detail,  the  chemistry 
of  the  common  metals,  salts  of  which  are  frequently  used  in  medicine 
or  in  testing  medicinal  substances.  These  are  : — 

Potassium,  Barium,  Zinc,  Arsenicum,  Mercury, 

Sodium,  Calcium,  Aluminium,  Antimony,  Lead, 

Ammonium  (?),  Magnesium,  Iron,  Copper,  Silver. 

There  still  remain  eleven  metals,  eight  of  wLich  are  mentioned  in 
the  British  Pharmacopoeia,  namely : — 

Lithium,  Chromium,  Gold,  Cadmium, 

Manganese,  Tin,  Platinum,  Bismuth. 

Compounds  of  the  remaining  three  are  sufficiently  common  to  occa- 
sionally come  under  notice  : — 

Strontium,  Cobalt,  Nickel. 

These  eleven  metals  of  minor  pharmaceutical  interest  may  be 
shortly  studied,  a few  only  of  the  reactions  of  each  (just  those  men- 
tioned in  the  following  pages)  being  performed.  When  all  have 
been  thus  treated,  their  respective  positions  in  the  analytical  groups 
will  be  indicated  and  a tabular  scheme  by  wffiich  an  analysis  of  a 
solution  containing  any  metal  may  be  effected.  Thus,  step  by  step, 
we  may  learn  how  to  analyze  almost  any  substance  that  may  occur, 
and  know  to  what  extent  the  presence  of  a rarer  wdll  interfere  with 
the  ordinary  tests  for  a common  element : additional  illustrations  of 
the  working  of  chemical  laws  will  be  acquired,  and  the  store  of 
chemical  and  pharmaceutical  facts  increased.  The  opportunity  thus 
afforded  for  improvement  in  habits  of  neatness  in  manipulation,  pre- 
cision, and  classification  is  another  and  no  mean  reason  why  such 
experiments  should  be  prosecuted,  the  direct  value  of  which  may  not 
be  considerable  to  medical  and  pharmaceutical  learners. 

LITHIUM. 

Symbol  L.  Atomic  weight  7. 

Lithium  is  widely  distributed  in  nature,  but  usually  in  minute  pro- 
portions compared  with  other  elements.  A trace  of  it  may  be  found 
in  most  soils  and  waters,  a Cornish  spring  containing  even  consider- 
able quantities  as  chloride. 

One  salt  used  in  medicine  is  the  Citrate  (L^Cgll507)  [Lithii 
Citras,  U.  S.  P.),  occurring  in  white  deliquesent  crystals  or  powder, 
prepared  by  dissolving  50  grains  of  the  Carbonate  (L^CO^)  and  100 
of  citric  acid  in  1 ounce  of  water,  evaporating  to  a low  bulk,  and 


LITHIUM. 


201 


setting  aside  in  a dry  place  to  crystallize,  or  at  once  evaporating  to 
dryness  and  powdering  the  residue. 

3L,C03  + = 2L3C,H,0,  + m,0  + 3CO., 

Carbonate  Citric  acid.  Citrate  of  Water.  Carbonic 

of  lithium.  lithium.  acid  gas. 

The  carbonate  {Litliii  Carhonas,  U.  S.  P.)  is  a white  granular 
powder  obtained  from  the  minerals  which  contain  lithium  ; namely, 
lepidolite  (from  lepis,  a scale,  and  uOo^,  Uthos,  a stone ; it  has 

a scaly  appearance),  triphane  (from  treis,  three,  and 

pliaind,  I shine),  or  spodumene  (from  cyrtoSdw,  spodod,  to  reduce  to 
ashes,  in  allusion  to  its  exfoliation  in  the  blowpipe-flame),  and  peta- 
lite  (from  rd'ta’Kov,  petalon,  a leaf ; its  character  is  leafy  and  lami- 
nated). Each  contains  silicate  of  aluminium,  with  fluoride  of  potas- 
sium and  lithium  in  the  case  of  lepidolite,  and  silicate  of  sodium  and 
lithium  in  the  others.  Liquor  Litliioe  Effervescens,  B.  P.,  is  a solu- 
tion of  10  grains  of  carbonate  of  lithium  in  1 pint  of  water  charged 
with  7 times  its  volume  of  carbonic  acid  gas  and  kept  in  ordinary 
aerated  water-bottles.  Half  a pint,  evaporated  to  dryness,  yields 
5 grains  of  a white  solid  residue,  answering  to  the  tests  for  carbonate 
of  lithium Ten  grains  of  the  latter  salt  neutralized  with  sul- 

phuric acid,  and  afterwards  heated  to  redness,  leave  14.86  grains  of 
dry  sulphate  of  lithium,  which,  when  redissolved  in  distilled  water, 
yields  no  precipitate  with  oxalate  of  ammonium  or  solution  of  lime,” 
indicating  absence  of  salts  of  calcium  and  aluminium.  Citrate  of 
lithium  should  yield  by  incineration  52.8  per  cent,  of  white  carbo- 
nate of  lithium. 

Urate  of  Lithium^  is  more  soluble  than  urate  of  sodium  ; hence 
lithium  preparations  are  administered  to  gouty  patients  in  the  hope 
that  urate  of  sodium,  with  which  such  systems  are  loaded,  may  be 
converted  into  urate  of  lithium  and  removed. 

In  chemical  position  lithium  stands  between  the  alkaline  and  the 
alkaline-earth  metals,  its  hydrate,  carbonate,  and  phosphate  being 
slightly  soluble  in  water.  The  double  chloride  of  platinum  and 
lithium  also  is  soluble  in  water.  Its  atom  is  univalent,  L'. 

Analytical  Reaction, — Moisten  the  end  of  a platinum 
wire  with  solution  of  a minute  particle  of  solid  lithium  salt, 
and  introduce  it  into  the  flame  of  a Bunsen  burner  or  other 
slightly  colored  flame  (spirit-lamp  or  blowpipe-flame)  ; a 
magnificent  crimson  tinge  is  imparted. 

The  light  emitted  by  ignited  lithium  vapor  is  of  a purer  scarlet 
than  that  given  by  strontium,  the  next  element.  When  the  flames 
are  examined  by  spectral  analysis  (physically  analyzed  by  a prism), 
the  red  rays  are,  in  the  case  of  strontium,  found  to  be  associated 
with  blue  and  yellow,  neither  of  which  is  present  in  the  lithium  light. 

* Urates  will  be  considered  subsequently  in  connection  with  uric 
acid. 


202 


RARER  METALLIC  RADICALS. 


STRONTIUM. 

Symbol  Sr.  Atomic  weight  87.5. 

^£ource. — Strontium  is  not  widely  distributed  in  nature ; but  the 
^bonate  (SrCOg),  known  as  strontzamte,  and  the  sulphate  (SrSO^) 
known  as  celestme  (from  coelum,  the  sky,  in  allusion  to  its  occasional 
bluish  color),  are  by  no  means  rare  minerals. 

Salts  of  strontium  are  not  employed  in  medicine.  They  are  chiefly 
used  by  firework  manufacturers  in  preparing  red  fire.  The  color 
they  impart  to  flame  is  a beautiful  crimson — ignited  strontium  vapor 
emitting  red  rays,  as  already  explained.  Nitrate  of  strontium 
(Sr2N03)  is  best  for  pyrotechnic  compositions,  its  oxygen  enabling 
it  to  burn  freely  when  mixed  with  charcoal,  sulphur,  etc.  It,  or  any 
salts,  may  be  obtained  by  dissolving  the  carbonate  in  the  appropriate 
acid,  or  by  igniting  the  cheaper  sulphate  with  coal,  whereby  sulphide 
(SrS)  is  produced,  and  dissolving  this  in  acid. 

The  position  of  strontium  among  the  chemical  elements  is  between 
barium  and  calcium ; its  sulphate  is  very  sparingly  soluble  in  water. 
Its  atom,  like  those  of  barium  and  calcium,  is  bivalent  (Sr"). 

Analytical  Reactions  (Tests). 

Firist  Analytical  Reaction^ — To  a solution  of  a strontium 
salt  (Sr2N03  or  SrCl^)  add  carbonate  of  ammonium  ; a 
white  precipitate  of  carbonate  of  strontium  (SrCOJ  falls. 

Second  Analytical  Reaction. — To  a solution  of  a stron- 
tium salt  add  sulphuric  acid  previously  so  diluted  that  it 
will  not  precipitate  calcium  salts  or  an  equally  dilute  solu- 
tion of  any  other  sulphate  ; a wdiite  precipitate  of  sulphate 
of  strontium  (SrSO^)  falls.  The  formation  of  this  pre- 
cipitate is  promoted  by  stirring  and  by"  setting  the  liquid 
aside  for  some  time. 

Barium  is  precipitated  immediately  under  similar  circumstances. 

Third  Analytical  Reaction. — To  a dilute  solution  of  a 
strontium  salt  add  yellow  chromate  of  potassium  ; no  pre- 
cipitate falls. 

Barium  may  be  separated  from  strontium  by  chromate  of  potas- 
sium, that  reagent  at  once  precipitating  barium  from  aqueous  or 
acetic  solutions. 

Fourth  Analytical  Reaction. — Insert  a fragment  of  a 
strontium  salt  in  the  blowpipe-flame,  or  other  equally 
colorless  flame,  or  hold  the  end  of  a platinum  wire  dipped 
into  a strontium  solution  in  the  flame ; a crimson  color  is 
imparted. 

Other  Analytical  Reactions. — Alkaline  phosphates,  arse- 
niates,  and  oxalates  give  white  insoluble  precipitates  with 


MANGANESE. 


203 


strontium  as  with  barium  and  calcium.- — —Strontium,  like 
calcium,  but  unlike  barium,  is  not  precipitated  by  hydro- 
fluosilicic  acid. 

Cerium.  Ce.  At.  wt.  22. — This  element  occurs  in  the  mineral 
cerite  (a  silicate  of  iron,  calcium,  and  the  three  rare  metals,  cerium, 
lanthanium,  and  didymium) ; also  occasionally  as  impure  fluoride, 
carbonate,  and  phosphate.  The  oxalate  of  cerium,  a white  granular 
powder,  is  the  only  official  salt ; it  may  be  obtained  from  cerite  by 
boiling  the  powdered  mineral  in  strong  hydrochloric  acid  for  several 
hours,  evaporating,  diluting,  and  filtering  to  separate  silica ; adding 
ammonia  to  precipitate  hydrates  of  all  the  metals  except  calcium ; 
filtering  off,  washing,  redissolving  in  hydrochloric  acid,  and  adding 
oxalic  acid  to  precipitate  oxalate  of  cerium.  The  preparation  will 
still  contain  oxalates  of  lanthanium  and  didymium ; it  is  therefore 
strongly  calcined,  the  resulting  oxides  of  lanthanium  and  didymium 
dissolved  out  by  boiling  with  a concentrated  solution  of  chloride  of 
ammonium,  the  residual  oxide  of  cerium  dissolved  in  hydrochloric 
acid,  and  oxalate  of  ammonium  added  to  precipitate  pure  oxalate  of 
cerium  (Ce"C.^04,  3H.^O). 

Oxalate  of  cerium  ( Gerii  Oxalas,  B.  P.  and  U.  S.  P.)  is  decom- 
posed at  a dull  red  heat,  a salmon-colored  mixture  of  oxides  remain- 
ing ; usually  a little  didymium  is  present,  giving  the  ignited  residue 
a reddish-brown  color ; it  is  then  soluble  in  boiling  hydrochloric  acid 
(without  effervescence;  indicating,  indirectly,  absence  of  earthy  and 
other  carbonates  or  oxalates),  and  the  solution  gives,  with  excess  of 
a saturated  solution  of  sulphate  of  potassium,  a crystalline  precipitate 
of  double  sulphate  of  cerium  and  potassium.  Alumina  mixed  with 
oxalate  of  cerium  may  be  detected  by  boiling  with  solution  of  potash, 
filtering,  and  adding  excess  of  solution  of  chloride  of  ammonium, 
when  a white  flocculent  precipitate  of  hydrate  of  aluminium  will  be 
obtained.  The  oxalic  radical  is  recognized  by  neutralizing  the  pot- 
ash solution  by  acetic  acid  and  adding  chloride  of  calcium ; white 
oxalate  of  calcium  is  then  precipitated ; this  precipitate,  though  in- 
soluble in  acetic,  should  be  wholly  dissolved  by  hydrochloric  acid. 

MANGANESE. 

Symbol  Mn.  Atomic  weight  55. 

Source. — Manganese  is  a constituent  of  many  minerals,  and  as 
black  oxide  (MnO.J  (Manganesii  Oxidum  Nigrum,  B.  P.  and 
U.  S.  P.),  or  pyrolusite  (from  Ttup,  pur,  fire,  and  lusts,  a loosing 
or  resolving,  in  allusion  to  the  readiness  with  which  it  is  split  up  by 
heat  into  a lower  oxide  and  oxygen),  occurs  frequently  in  abundance 
in  the  southwest  of  England,  Aberdeenshire,  and  most  of  the  coun- 
tries of  Europe.  It  is  met  wdth  as  a steel-gray  mass  of  prismatic 
crystals,  or  in  black  shapeless  lumps. 

The  chemical  position  of  manganese  is  close  to  iron  and  three 
other  metals  still  to  be  considered — cobalt,  nickel,  and  chromium. 
Its  atom  apparently  has  sexivalent  affinities,  as  seen  in  manganate 
of  potassium  (K2Mn04) ; but  commonly  it  is  quadrivalent  (Mn^^)  or 
bivalent  (M"). 


204 


RARER  METALLIC  RAIUCALS. 


Uses. — Metallic  manganese  is  only  used  in  alloy  with  iron  in  the 
manufacture  of  some  varieties  of  steel.  The  black  oxide  is  an  im- 
portant agent  in  the  production  of  chlorine,  the  preparation  of  green 
and  red  disinfecting  manganates,  purple  glass,  and  black  glazes  for 
earthenware. 

Reactions  having  either  Synthetical  or  Analytical  Interest., 

or  both. 

First  Reaction, — Boil  a few  grains  of  black  oxide  of 
manganese  with  so£pe  drops  of  hydrochloric  acid  until 
chlorine  ceases  to  be  evolved  ; add  water,  and  filter  ; the 
filtrate  is  a solution  of  manganous  chloride  (MnClJ. 

MnO,  + 4HC1  = MnCl,  + 2H,0  + Cl,. 

This  is  the  reaction  commonly  applied  in  the  preparation  of  chlo- 
rine gas.  It  is  also  a ready  method  of  preparing  a manganous  salt 
for  analytical  experiments.  Coupled  with  the  application  of  reagents 
to  the  filtrate,  the  reaction  is  that  by  which  a black  powder  or  mine- 
ral would  be  recognized  as  black  oxide  of  manganese.  Black  oxide 
of  manganese  dissolves  in  cold  hydrochloric  acid,  forming  a dark- 
brown  solution  of  a higher  chloride  or  chlorides,  MnClg,  Mn^Cl^,  or, 
possibly,  MnCl^. 

Second  Reaction, — Heat  a particle  of  a manganese  com- 
pound with  a grain  or  two  of  carbonate  and  hydrate  of 
potassium  and  a fragment  of  nitrate  or  chlorate  of  potas- 
sium on  platinum  foil  in  the  blowpipe-flame;  a green  mass 
containing  many  an  ate  of  potassium  (K^MnOj  results. 
Boil  the  foil  in  a little  water  ; the  green  manganate  dis- 
solves and  soon  changes  to  solution  of  the  purple  perman- 
ganate of  potassium  (K^Mn,Oy). 

This  is  a delicate  analytical  test  for  manganese. 

The  reaction  is  similar  to  that  by  which  permanganate  of  potas- 
sium [Potassii  Permanganas,  U.  8.  P.)  is  directed  to  be  prepared 
for  use  in  volumetric  analysis.  Liquor  Potassii  Permanganatisy 
U.  8.  P.,  is  a solution  of  80  grains  of  permanganate  of  potassium  in 
1 pint  of  distilled  water.  Equations  showing  the  exact  action  which 
occurs  in  making  the  salt  according  to  the  process  of  the  British 
Pharmacopoeia  have  already  been  given  in  connection  with  the  com- 
pounds of  potassium  (vide  p.  64).  The  proportions  of  ingredients 
and  details  of  the  operation  are  as  follows  : — 

lleduce  3^  parts  (for  experiment  each  “ part”  may  be  ^th  oz.)  of 
chlorate  of  potassium  to  fine  powder,  and  mix  it  with  4 of  black 
oxide  of  manganese  ; put  the  mixture  into  a porcelain  basin,  and  ( 
add  to  it  5 parts  of  solid  caustic  potash,  previously  dissolved  in  4 | 
parts  of  water.  Evaporate  to  dryness,  stirring  diligently  to  prevent 
spirting.  Pulverize  the  mass,  put  it  into  a covered  Hessian  or 
Cornish  crucible,  and  expose  it  to  a dull  red  heat  (not  higher)  for  an 


MANGANESE. 


205 


hour  (20  or  30  minutes  for  quantities  of  1 or  2 ozs.),  or  till  it  has 
assumed  the  condition  of  a semifused  mass.  Allow  to  cool,  pulverize, 
and  boil  with  about  30  parts  of  water.  Let  the  insoluble  matter 
subside,  decant  the  fluid,  boil  again  with  about  10  parts  of  water, 
again  decant,  neutralize  the  united  liquors  accurately  with  diluted 
sulphuric  acid  (or,  better,  carbonic  acid  gas),  and  evaporate  till  a 
pellicle  forms.  Set  aside  to  cool  and  crystallize.  Drain  the  crystal- 
line mass,  boil  it  in  6 parts  of  water,  and  strain  through  a funnel  the 
throat  of  which  is  lightly  obstructed  by  a little  asbestos  or  gun-cot- 
ton. Let  the  fluid  cool  and  crystallize,  drain  the  dark  purple  slen- 
der prismatic  crystals,  and  dry  them  by  placing  under  a bell  jar  over 
a vessel  containing  sulphuric  acid. 

Instead  of  converting  the  manganate  into  permanganate  by  ebul- 
lition, by  which  one-third  of  the  manganate  is  lost,  Stadelar  recom- 
mends chlorine  to  be  passed  through  the  cold  solution  until  the  green 
color  is  entirely  changed  to  purple. 

Solutions  of  the  manganates  of  potassium  and  sodium  are  in  com- 
mon use  as  disinfectants  under  the  name  of  Condy’s  fluid.  They  act  by 
oxidizing  organic  matter,  the  manganic  or  permanganic  radical  being 
reduced  to  black  manganic  oxide,  or  even  a lower  oxide.  The  reason 
for  using  asbestos  instead  of  paper  in  filtering  the  solutions  will  now 
be  understood. 

The  changes  in  color  which  the  green  mass  of  the  above  process 
undergoes  when  dropped  into  warm  water  procured  for  it  the  old 
name  of  mineral  chameleon. 

Third  Reaction. — Make  a borax  bead  by"  heating  a frag- 
ment of  the  salt  on  the  looped  end  of  a platinum  wire  in 
the  blowpipe-fllame  until  a clear  transparent  globule  is  ob- 
tained. Place  on  the  bead  a minute  portion  of  a manga- 
nese compound,  or  touch  it  with  a drop  of  solution.  Again 
fuse  the  borax  ; a bead  of  a violet  or  amethystine  tint  is 
produced. 

This  is  a good  analytical  reaction.  It  has  also  synthetical  interest, 
illustrating  the  use  of  black  oxide  of  manganese  in  producing  common 
purple-tinted  glass. 

Expose  the  bead  to  the  reducing  part  of  the  flame,  the 
part  nearer  to  the  blowpipe,  where  there  are  highly  heated 
hydro-carbon  gases  greedy  of  oxygen  ; the  color  disappears. 

This  is  owing  to  the  reduction  of  the  manganic  compound  to  a 
manganous  condition,  in  which  it  no  longer  possesses  peculiar  color- 
ing-power. This  action  also  illustrates  the  use  of  black  oxide  of 
manganese  in  glass-manufacture.  Glass  when  first  made  is  usually 
of  a green  tint,  owing  to  the  presence  of  ferrous  impurities;  the 
addition  of  manganic  oxide  to  the  materials  converts  the  ferrous  into 
ferric  compounds,  which  have  comparatively  little  colorific  power,  it 
itself  being  thereby  reduced  to  manganous  oxide,  which  also  gives 
but  little  color.  If  excess  of  manganic  oxide  be  added,  a purple  tint 
is  produced. 

18 


20  G 


RARER  M E T A L I.  I C RADICALS. 


Fourth  Reaction, — Through  a solution  of  a manganous 
salt  acidified  by  hydrochloric  acid  pass  sulphuretted  hydro- 
gen ; no  decomposition  occurs.  Add  ammonia;  the  sul- 
phydrate  of  ammonium  thus  formed  causes  the  precipitation 
^f  a yellowish-pink  or  flesh-tinted  precipitate  of  manganous 
sulphide  (MnS)  in  a hydrous  state. 

This  reaction  is  characteristic,  sulphide  of  manganese  being  the 
only  flesh-colored  sulphide  known.  The  salt  used  may  be  the  manga- 
nous chloride  obtained  in  the  first  reaction ; but  such  crude  solutions 
usually  give  a black  precipitate  with  sulphydrate  of  ammonium, 
owing  to  the  presence  of  iron.  The  latter  element  may  be  removed, 
however,  on  boiling  the  manganous  solution  with  a little  carbonate 
of  sodium,  which  throws  the  ferric  salt  out  of  solution  before  the 
manganous.  Pure  manganous  chloride  may  be  similarly  obtained 
on  boiling  the  impure  solution  with  manganous  carbonate  ; the  latter 
decomposes  the  ferric  chloride  with  production  of  ferrric  hydrate  and 
more  manganous  chloride,  and  evolution  of  carbonic  acid  gas. 

To  the  recently  precipitated  manganous  sulphide  add 
acetic  acid;  it  is  dissolved. 

This  solubility  enables  manganese  to  be  separated  from  nickel,* 
cobalt,  and  zinc,  whose  sulphides  are  insoluble  in  weak  acetic  acid. 
To  express  the  fact  in  another  way — manganese  is  not  precipitated 
by  sulphuretted  hydrogen  from  a solution  containing  free  acetic  acid 
only. 

Fifth  Reaction, — To  solution  of  manganous  salt  add 
ammonia  drop  by  drop;  a white  precipitate  of  manganous 
hydrate  (Mn2HO)  falls.  Add  excess  of  ammonia;  the 
precipitate  is  dissolved. 

The  fixed  alkalies  give  a similar  precipitate  insoluble  in  excess. 
The  precipitate  rapidly  absorbs  oxygen,  becomes  brown,  and  gradu- 
ally passes  into  a higher  oxide. 

Sixth  Reaction, — Heat  a little  black  oxide  of  manganese 
in  a test-tube  with  sulphuric  acid ; oxygen  is  evolved  and  sul- 
phate of  manganese  formed  {Mangayiesii  Sulphas^  XJ.  8.  P.), 
add  water,  boil,  filter,  evaporate,  and  set  aside  to  crystallize. 
Larger  quantities  are  made  in  a similar  manner. 

Sulphate  of  manganese  (MnS04,5H.,0)  occurs  in  colorless,  or  pale 
rose-colored,  transparent  crystals,  which,  when  deposited  from  a solu-  i 
tion  at  a temperature  between  68^  and  86^,  have  the  form  of  right ; 
rhombic  prisms,  and  contain  four  molecules  of  water.  This  salt  is  - 
very  soluble  in  water.  The  solution  is  not  colored  by  tincture  of 
nutgall  a black  (a  black  shows  iron),  but  affords  wfith  caustic  alkalies 
a white  precipitate  (Mn2HO),  wLich,  by  exposure  to  the  air,  soon 
absorbs  oxygen,  and  becomes  brown.  Sulphydrate  of  ammonium 
throws  down  a flesh-colored  precipitate  (MnS),  and  ferrocyanide  of 
potassium,  a white  one  (Mn^Fcy).  |j 


COBALT. 


201 


Many  other  reactions  occur  between  manganese  salts 
and  various  reagents,  but  are  of  no  particular  synthetical  or 
analytical  interest.  A good  method  proposed  by  Crum, 
for  detecting  minute  quantities  of  manganese,  consists  in 
adding  dilute  nitric  acid  and  the  puce-colored  oxide  or  per- 
oxide of  lead  to  the  solution,  and  then  boiling ; a red  tint, 
duetto  permanganic  acid,  is  imparted  to  the  liquid. 


COBALT. 

Symbol  Co.  Atomic  weight  58.8. 


Source. — Cobalt  occurs  sparingly  in  nature  as  the  arsenide  (Co  AS2), 
or  tin-white  cohalt,  and  occasionally  as  a double  arsenide  and  sul- 
phide (CoASg,  C0S2),  or  cohalt-glance  (from  glanz,  brightness,  in 
allusion  to  its  lustre). 

Uses. — It  chief  use  is  in  the  manufactory  of  blue  glass,  the  color 
of  which  is  due  to  a compound  of  cobalt.  Cobalt  is  also  the  coloring 
constituent  of  smalt  (from  smelt,  a corruption  of  melt),  a finely-ground 
sort  of  glass  used  as  a blue  pigment  by  paper-stainers  and  others,  and 
employed  also  by  laundresses  to  neutralize  the  yellowish  appearance 
of  washed  linen. 

The  salts  of  cohalt  may  be  obtained  from  the  oxide  (CoO),  and 
the  oxide  from  zajfre,  a mixture  of  sand  and  roasted  ore. 

Quant ivalence. — Cobalt  often  exhibits  quadrivalent  affinities,  but 
still  more  often  exerts  only  bivalent  powers  (Co").  It  has  analyti- 
cal relations  with  zinc,  nickel,  and  manganese,  and  may  be  regarded 
as  a member  of  the  iron  group. 


Analytical  Reactions  (Tests). 


First  Analytical  Reaction. — Pass  sulphuretted  hydrogen 
through  a solution  of  a salt  of  cobalt — the  chloride  (C0CI2) 
or  nitrate  (C02NO3)  for  example  ; no  decomposition  occurs. 
Add  ammonia;  the  sulphydrate  of  ammonium  thus  formed 
causes  the  precipitation  of  black  sulphide  of  cobalt  (CoS). 

The  moist  precipitate  slowly  absorbs  oxygen  from  the  air,  becom- 
ing converted  into  sulphate  of  cobalt  (C0SO4). 

Second  Analytical  Reaction. — Add  ammonia  gradually  to 
a cobalt  solution ; a blue  precipitate  of  impure  h}- drate  of 
cobalt  (Co2HO)  falls.  Add  excess  of  ammonia;  the  pre- 
cipitate is  dissolved. 

A similar  precipitate  is  given  by  the  fixed  alkalies,  insoluble  in 
excess. 

Third  Analytical  Reaction. — Make  a borax  bead  by  heat- 
ing a fragment  of  the  salt  on  the  looped  end  of  a platinum 
wire  in  a blowpipe-flame  until  a clear  transparent  globule 


208 


RARER  METALLIC  RADICALS. 


is  obtained.  Place  on  the  bead  a minute  portion  of  cobalt 
compound,  or  touch  it  with  a drop  of  solution.  Again 
fuse  the  borax ; a blue  bead  results. 

This  is  a delicate  test  for  cobalt.  From  what  has  previously  been 
said,  it  will  be  seen  that  this  experiment  has  also  considerable  syn- 
thetical interest. 

Fourth  Analytical  Reaction, — To  a solution  of  a salt 
of  cobalt  add  two  or  three  drops  of  hydrochloric  acid, 
then  excess  of  solution  of  cyanide  of  potassium,  and  boil 
for  ten  minutes ; oxygen  is  absorbed,  and  cobalticyanide  of 
potassium  (K(.Co2Cyj2)  formed.  Add  hydrochloric  acid,  and 
boil  the  mixture  (in  a fume-cupboard,  to  avoid  inhalation 
of  any  hydrocyanic  acid)  ; the  excess  of  cyaiiide  of  potas- 
sium is  thus  decomposed,  but  the  cobaltic3^anide  is  un- 
affected. Now  add  excess  of  solution  of  potash;  the 
cobalticyanide  of  potassium  is  decomposed,  the  hydrate  of 
cobalt  formed  remaining  dissolved  in  the  alkaline  liquid. 

Nickel  under  similar  circumstances  is  precipitated,  the  reaction 
thus  affording  means  of  separating  these  closely  allied  metals  from 
each  other. 

Other  reactions  between  a cobalt  solution  and  different 
reagents  may  be  performed,  and  various  precipitates  ob- 
tained ; but  these  have  no  special  analytical  interest. 

Invisible  Ink, — The  salts  of  cobalt  containing  water  of 
ciystallization  are  light  red,  the  anh^^drous  more  or  less 
blue.  Prove  this  by  writing  some  words  on  paper  with  a 
solution  of  chloride  of  cobalt  sufficiently  dilute  for  the 
characters  to  be  invisible  when  dry;  hold  the  sheet  before' 
a fire  or  over  a flame ; the  letters  at  once  become  visible, 
distinct  and  of  a blue  color.  Breathe  on  the  words,  or  set 
the  sheet  aside  for  a while  ; the  characters  are  once  more 
invisible,  owing  to  absorption  of  moisture.  Hence  solu- 
tion of  chloride  of  cobalt  forms  one  of  the  so-called  sym- 
pathetic inks, 

NICKEL. 

Symbol  Ni.  Atomic  weight  58.8. 

Nickel  is,  chemically,  closely  allied  to  cobalt,  the  ores  of  the  two 
metals  being  commonly  associated  in  nature.  Indeed  it  is  from  speiss^ 
an  arsenio-sulphide  of  nickel  obtained  in  the  manufacture  of  smalt,  a 
pigment  of  cobalt  already  mentioned,  that  most  of  the  nickel  met 
with  in  commerce  is  obtained.  It  is  much  used  in  the  preparation 
of  the  white  alloy  known  as  German  or  nickel  silver. 


NICKEL. 


209 


Quantivalence. — Nickel  exerts  bivalent  activity  (Ni")  in  its  ordi- 
nary compounds.  Its  salts  and  their  solutions  are  usually  green. 
They  are  chiefly  made,  directly  or  indirectly,  from  the  metal  itself. 

Analytical  Beactions  ( Tests), 

First  Analytical  Reaction. — Pass  sulphuretted  hydrogen 
through  a solution  of  a salt  of  nickel — chloride  (NiClJ, 
nitrate  (Ni2N03),  or  sulphate  (NiSOJ  ; no  decomposition 
occurs.  Add  ammonia;  the  sulphydrate  of  ammonium 
thus  formed  causes  the  precipitation  of  black  sulphide  of 
nickel  (NiS). 

Note. — When  sulphide  of  nickel  is  precipitated  by  the  direct 
addition  of  the  common  yellow  solution  of  sulphydrate  of  ammonium, 
which  always  contains  sulphur,  there  is  much  difficulty  in  filtering 
the  mixture,  owing  to  the  slight  solubility  of  the  sulphide  of  nickel 
in  the  reagent  and  the  formation  of  some  sulphate  of  nickel  (NiS04), 
oxygen  being  absorbed  from  the  air  by  the  sulphide.  This  may  be 
avoided  by  warming  the  mixture  and  using  freshly-made  sulphydrate 
of  ammonium,  in  which  the  sulphide  of  nickel  is  insoluble  ; or,  where 
practicable,  the  salt  of  nickel  may  be  precipitated  from  an  ammo- 
niacal  solution  by  sulphuretted  hydrogen. 

Second  Analytical  Reaction. — Add  ammonia  drop  by  drop 
to  a nickel  solution ; a pale-green  precipitate  of  hydrate  of 
nickel  (Ni2HO)  falls.  Add  excess  of  ammonia ; the  pre- 
cipitate dissolves. 

A similar  precipitate  is  given  by  the  fixed  alkalies,  insolu- 
ble in  excess. 

Third  Analytical  Reaction, — Nickel  salts  color  a borax 
bead,  when  hot,  a reddish-yellow  tint ; the  reaction  is  not 
very  serviceable  analytically. 

Fourth  Analytical  Reaction. — To  a solution  of  a salt  of 
nickel  add  solution  of  cyanide  of  potassium ; cyanide  of 
nickel  (NiCy2)  is  precipitated.  Add  excess  of  solution  of 
cyanide  of  potassium ; the  precipitate  is  dissolved  with 
formation  of  double  cyanide  of  nickel  and  potassium 
(NiCy2,2KCy).  Next  add  hydrochloric  acid,  and  boil  the 
mixture  (in  a fume-cupboard),  adding  a little  hj^drochloric 
acid  from  time  to  time  until  all  smell  of  hydrocyanic  acid 
has  disappeared.  Lastl}^,  add  excess  of  solution  of  potash  ; 
hydrate  of  nickel  is  precipitated. 

This  reaction  serves  for  the  separation  of  nickel  from  cobalt.  On 
adding  excess  of  hydrochloric  acid  to  a solution  containing  the  two 
metals,  together  with  cyanide  of  potassium,  a precipitate  of  cyanide 
of  nickel  and  cobalticyanide  of  nickel  occurs.  By  ebullition  with 
excess  of  hydrochloric  acid  the  cyanide  of  nickel  is  decomposed, 

18=*^ 


210 


RARER  METALLIC  RADICALS. 


chloride  of  nickel  going  into  solution.  On  then  adding  excess  of 
potash  hydrate  of  nickel  is  precipitated.  The  cobalticyanide  of 
nickel  is  not  decomposed  by  the  acid ; but  it  is  by  the  alkali,  its 
cobalt  going  into  solution  and  its  nickel  remaitiing  insoluble  as 
hydrate. 

After  filtering  off  the  nickel,  cobalt  is  detected  in  the  filtrate  by 
evaporating  to  dryness  and  testing  the  residue  with  borax  in  the 
blowpipe-flame. 

Other  reactions  between  a nickel  solution  and  various 
reagents  give,  in  many  cases,  insoluble  precipitates  which, 
from  their  green  color,  are  occasionally  useful  in  distin- 
o'uishing  nickel  from  allied  elements. 

o O 


CHROMIUM. 

Symbol  Cr.  Atomic  weight  52.5. 

Source. — The  chief  ore  of  chromium  is  chrome  ironstone,  a mix- 
ture of  the  oxides  of  the  metals  (FeO,  Cr203),  occurring  chiefly  in 
the  United  States  and  Sweden.  In  constitution  it  seems  to  resemble 
magnetic  iron  ore  (FeO,  Fe203). 

Preparation  of  Red  Chromate  of  Potassium. — On  roasting  the 
powdered  ore  with  carbonate  of  potassium  and  nitre,  yellow  chro- 
mate of  potassium  (K2Cr04)  is  obtained ; the  mass,  treated  with 
acid,  yields  red  or  bichromate  (K2Cr04,  Cr03)  [Potassii  BichromaSy 
U.  S.  P.);  from  this  salt  other  chromates  are  prepared,  and  by 
reduction,  as  presently  explained,  the  salts  of  chromium  itself.  The 
yellow  and  orange  chromates  of  lead  are  largely  used  as  pigments. 

Note  on  Constitution. — Red  chromate  of  potassium  is  a somewhat 
abnormal  salt,  containing,  probably,  neutral  chromate  associated  with 
chromic  anhydride.  The  value  of  chromates  as  chemical  reagents  is 
alluded  to  in  connection  with  chromate  of  barium  (p.  88).  Heated 
strongly  in  a crucible,  red  chromate  of  potassium  splits  up  into  yellow 
chromate,  glistening  oxide  of  chromium,  and  oxygen. 

Quantivalence. — Chromium  stands  in  close  chemical  relation  to 
iron,  aluminium,  and  manganese.  Its  atom  is  sexivalent  if  the  for- 
mula of  the  fluoride  (CrFg)  be  correct.  Like  iron  and  aluminium,  it 
is  trivalent,  as  seen  in  chromic  chloride  (Cr.,Clg),  but  sometimes  exerts 
only  bivalent  activity,  as  in  chromous  chloride  (CrCl2). 

Passage  of  Chromium  from  the  Acidulous  to  the  Basylous 
Side  of  Salts. — Through  an  acidified  solution  of  red  chro- 
mate of  potassium  pass  sulphuretted  hydrogen ; sulphur 
is  deposited,  and  a green  salt  of  chromium  remains  in  solu- 
tion— chloride  (Cr2Clg)  if  hydrochloric  acid  be  used,  and 
sulphate  (Cr23SOJ  if  sulphuric  be  the  acid  employed.  Boil 
the  liquid  to  expel  excess  of  sulphuretted  hydrogen,  filter, 
^nd  reserve  the  solution  for  subsequent  experiments. 

Alcohol,  sugar,  or  almost  any  substance  which  is  tolerably  liable 
to  oxidation,  will  answer  as  well  as  sulphuretted  hydrogen. 


CHROMIUM. 


211 


Sulphate  of  chromium  (Cr23S04),  like  sulphate  of  aluminium 
(AI23SO4),  unites  with  alkaline  sulphates  to  form  alums,  which  re- 
semble common  alum  both  in  crystalline  form  and,  as  far  as  we  know, 
in  internal  structure  ; they  are  of  a purple  color. 

Reactions. 

Chromium  as  Chromic  Acid^  or  other  Chromate. — This 
is  the  state  in  which  chromium  will  usually  be  met  with, 
the  most  common  salt  Seing  the  red  chromate  or  bichro- 
mate of  potassium.  Mix  four  volumes  of  a cold,  saturated 
aqueous  solution  of  red  chromate  of  potassium  with  five 
of  oil  of  vitriol ; on  cooling,  chromic  anhydride  (CrOg), 
Acidum  Chi'omicum^  U.  S.  P.,  separates  in  crimson  needles. 
After  well  draining,  the  crystals  may  be  freed  from  adhering 
sulphuric  acid  by  washing  once  or  twice  with  nitric  acid : 
the  latter  may  t3e  removed  by  passing  dried  and  slightly 
warmed  air  through  a tube  containing  the  crystals.  In 
contact  with  moisture  chromic  anhydride  takes  up  water 
and  forms  solution  of  true  chromic  acid  (H2Cr04).  Chro- 
mic anhydride  is  a powerfully  corrosive  oxidizing  agent. 
It  melts  between  356°  and  314°. 

The  oxygen  in  chromic  acid  and  other  chromates,  and  in  mangan- 
ates,  permanganates,  black  oxide  of  manganese  and  puce  colored 
oxide  of  lead  is  in  a physically  different  state  to  that  in  peroxide  of 
hydrogen,  peroxide  of  barium,  and  similar  compounds.  On  bringing 
chromic  acid  or  the  above  acidified  solution  of  red  chromate  of  potas- 
sium into  contact  with  solution  of  peroxide  of  hydrogen,  a strong 
effervescence  of  oxygen  ensues.  According  to  Schdnbein  and  Brodie 
the  oxygen  of  chromic  acid  is  in  the  negative  or  ozonic  state,  while 
that  of  peroxide  of  hydrogen  is  in  the  positive  or  antozonic  condition. 
Both  are  equally  active,  but  neutralize  each  other,  forming  neutral 
or  ordinary  oxygen. 

In  the  analytical  examination  of  solutions  containing 
chromates,  the  chromium  will  always  come  out  in  the  state 
of  green  chromic  hydrate  along  with  ferric  hydrate  and 
alumina,  the  prior  treatment  by  sulphuretted  hydrogen  re- 
ducing the  molecule  to  the  lower  state,  thus : — 

K2Cr04,  CrOg  + 8HC1  -f  3H^S  = Cr2Cl,  + 2KC1 

-b  7H2O  + Sg. 

Chromium  having  been  found  in  a solution,  its  condition 
as  chromate  may  be  ascertained  by  applying  to  the  original 
solution'  salts  of  barium,  mercury,  lead,  and  silver.  (See 
the  various  paragraphs  relating  to  those  metals.) 


212 


RARER  METALLIC  RADICALS. 


Ba2N03  gives  yellow  BaCrO^  with  chromates. 

Ho:22N03  “ red  Hg\^GrO^  “ 

AgNOg  ‘‘  “ Ag2Cr04  “ 

‘‘  ‘‘  Ag2Cr04,Cr03  with  bichromates. 

Pb2C2H303  ‘‘  yellow  PbCrO^  Mdth  both. 

Nitrate  of  barium  does  not  completely  precipitate  bichromates, 
bichromate  of  barium  being  soluble  in  water;  the  chromate  of  barium 
is  insoluble  in  water  or  acetic  acid,  but  soluble  in  hydrochloric  or 
nitric  acid.  Mercurous  nitrate  does  not  wholly  precipitate  bichro- 
mates : mercuric  nitrate  or  chloride  only  partially  precipitates  chro- 
mates, and  does  not  precipitate  bichromates.  The  mercurous  chro- 
mate is  insoluble,  or  nearly  so,  in  diluted  nitric  acid.  Acetate  of 
lead  precipitates  chromates  and  bichromates,  acetic  acid  being  set 
free  in  the  latter  case.  The  silver  chromates  are  soluble  in  acids  and 
alkalies. 

A delicate  reaction  for  dry  chromates  will  be  found  in 
the  formation  of  chlorochromic  anhydride  (Cr02Cl2).  A 
small  portion  of  the  chromate  is  placed  in  a test-tube  with 
a fragment  of  dry  chloride  of  sodium  and  a drop  or  two  of 
oil  of  vitriol,  and  the  mixture  heated  ; red  irritating  fumes 
of  chlorochromic  anhydride  are  evolved,  and  condense  in 
dark  red  drops  on  the  side  of  the  tube. 

Large  quantities  of  pure  distilled  chlorochromic  anhydride  are 
obtained  by  the  same  reaction,  the  operation  being  conducted  in  a 
retort,  with  thoroughly  dry  materials,  for  the  compound  is  decom- 
posed by  water.  It  may  be  regarded  as  chromic  anhydricie  in  which 
an  atom  of  oxygen  is  displaced  by  an  equivalent  quantity  (two  atoms) 
of  chlorine.  It  is  not  used  in  medicine,  but  is  of  interest  to  the 
chemical  student  as  being  an  illustration  of  a large  class  of  similar 
bodies — chloro-acidulous  or  chloro-anhydro  compounds. 

Analytical  Reactions  of  Chromium  Salts  (Tests). 

First  Analytical  Reaction. — To  solution  of  a salt  of  chro- 
mium (chloride,  sulphate,  or  chrome  alum)  add  sulphydrate 
of  ammonium;  a bulky  green  precipitate  of  chromic  hy- 
drate (Cr^GHO),  containing  a large  quantity  of  water  (7 
molecules,  7H2O),  is  precipitated. 

Cr^Cl,  + GAmHS  + 6H2O  = Cr26HO  + GAmCl  + 6H2S. 

Second  Analytical  Reaction To  solution  of  a chromium 

salt  add  ammonia;  chromic  hydrate  is  precipitated,  insolu- 
ble in  excess. 

Third  Analytical  Reaction. — To  solution  of  a chromium 
salt  add  solution  of  potash  or  soda  drop  by  drop  ; chromic 
hydrate  is  precipitated.  Add  excess  of  the  fixed  alkali ; 


TIN. 


213 


the  precipitate  is  dissolved.  Well  boil  the  solution  ; the 
chromic  hj^drate  is  reprecipitated. 

Iron,  Chromium,  and  Aluminium  Salts,  chemically  so  alike,  may 
be  separated  by  this  reaction.  Ferric  hydrate  is  insoluble  in  solu- 
tions of  the  fixed  alkalies,  cold  or  hot;  chromium  hydrate  soluble  in 
cold  but  not  in  hot;  hydrate  of  aluminium  in  both.  To  a solution 
containing  all  three  metals,  therefore,  add  potash  or  soda,  stir,  and 
filter ; the  iron  is  thrown  out : boil  the  filtrate,  and  filter  : the  chro- 
mium is  thrown  out : neutralize  the  filtrate  by  acid,  and  then  add 
ammonia ; the  aluminium  is  thrown  out.  The  three  hydrates  are 
insoluble  in  ammonia,  and  may  therefore  be  easily  separated  from  the 
hydrates  of  the  somewhat  analogous  metals  zinc,  cobalt,  nickel,  and 
manganese. 

Fourth  Analytical  Reaction, — Add  a salt  of  chromium 
(either  of  the  above  precipitates  of  chromic  oxide  or  the 
dry  residue  of  the  evaporation  of  a few  drops  of  a solu- 
tion of  a chromium  salt)  to  a few  grains  of  nitre  and  car- 
bonate of  sodium  on  platinum  foil,  and  fuse  the  mixture 
in  the  blowpipe-flame  ; a yellow  mass  of  chromate  of  potas- 
sium and  sodium  (KNaCrOJ  is  formed.  Dissolve  the 
mass  in  water,  add  acetic  acid  to  decompose  excess  of 
carbonate,  and  apply  the  reagents  for  chromates. 

This  is  a delicate  and  useful  reaction  if  carefully  per- 
formed. 


TIN. 

Symbol  Sn.  Atomic  weight  118'. 

Source. — The  chief  ore  of  tin  is  stannic  oxide  (81102),  occurring  in 
veins  under  the  name  of  tinstone,  or  in  alluvial  deposits  as  stream- 
tin.  The  principal  mines  are  those  of  Cornwall. 

Preparatiooi. — The  metal  is  obtained  by  reducing  the  roasted  and 
washed  ore  by  charcoal  or  anthracite*  coal  at  a high  temperature, 
and  is  purified  by  slowly  heating,  when  the  pure  tin,  fusing  first,  is 
•run  off,  a somewhat  less  fusible  alloy  of  tin  with  small  quantities  of 
arsenicum,  copper,  iron,  or  lead  remaining.  The  latter  is  known  as 
hloclc  tin  ; the  former  heated  till  brittle  and  then  hammered  or  let 
fall  from  a height  splits  into  prismatic  fragments  resembling  starch 
or  basalt,  and  is  named  dropped  or  grain  tin.  Good  tin  emits  a 
crackling  noise  in  bending,  termed  the  cry  of  tin,  caused  by  the 
friction  of  its  crystalline  particles  on  each  other. 

Uses. — Tin  is  an  important  constituent  of  such  alloys  as  pewter, 
Britannia  metal,  solder,  speculum-metal,  bell-metal,  gun-metal,  and 

* Anthracite  (from  civOpa^,  anthrax,  a burning  coal)  or  stone  coal 
differs  from  the  ordinary  bituminous  or  caking  coal,  in  containing  less 
volatile  matter,  and,  therefore,  in  burning  without  flame.  It  gives  a 
higher  temperature,  and  from  its  non-caking  properties  is,  in  furnace 
operations,  more  manageable  than  bituminous  coal. 


214 


RARER  METALLIC  RADICALS. 


bronze.  It  is  very  ductile,  and  may  be  rolled  into  plates  or  leaves, 
known  as  ^m/o27,  varying  from  to  of  an  inch  in  thickness. 
Common  tin  foil,  however,  usually  contains  a large  proportion  of  lead. 
The  reflecting  surface  of  most  looking-glasses  is  an  amalgam  of  tin 
and  mercury,  produced  by  carefully  sliding  a plate  of  glass  over  a 
sheet  of  tin  foil  on  which  mercury  has  been  rubbed,  and  then  excess 
of  mercury  poured.  Pins  are  made  of  brass  wire  on  which  tin  is 
deposited.  Tin  'plate,  of  which  common  utensils  are  made,  is  iron 
alloyed  with  tin  by  dipping  the  cleansed  sheet  into  melted  tin.  Tin 
tacks  are  in  reality  tinned  iron  tacks ; a tin  nail  would  be  too  soft  to 
drive  into  wood.  Tin  maybe  granulated  by  melting  and  triturating 
briskly  in  a hot  mortar,  by  shaking  melted  tin  in  a box  on  the  inner 
sides  of  which  chalk  has  been  rubbed,  or,  in  thin  little  bells  or  cor- 
rugated fragments  (Granulated  Tin,  B.  P.),  by  melting  in  a ladle 
and,  as  soon  as  fluid,  pouring  from  the  height  of  a few  feet  into 
water. 

The  chemical  position  of  tin  among  the  metals  is  close  to  that 
of  arsenicum  and  antimony.  Its  atom  is  quadrivalent  and  bivalent. 
The  two  classes  of  salts  are  termed  stannic  and  stannous  respectively. 
They  are  all  made  directly  or  indirectly  from  the  metal  itself. 


Reactions  having  [a)  Synthetical  and  (5)  Analytical  Interest. 

(a)  Synthetical  Reactions, 

Chloride  of  Tin.  Stannous  Chloride. 

First  Synthetical  Reaction, — Warm  a fragment  of  tin 
with  hydrochloric  acid ; hydrogen  escapes  and  solution  of 
stannous  chloride  (SnClJ  is  formed.  It  may  be  retained 
for  future  experiments. 

One  ounce  of  tin  dissolved  in  three  fluidounces  of  hydrochloric 
acid  and  one  of  water,  and  the  resulting  solution  diluted  to  five  fluid- 
ounces,  constitutes  the  “Solution  of  Chloride  of  Tin,”  B.  P. 

Solid  stannous  chloride. — By  evaporation  of  the  above  solution 
stannous  chloride  is  obtainable  in  crystals  (SnCl.,2H20).  It  is  a 
powerful  reducing  agent,  even  a dilute  solution  precipitating  gold, 
silver,  and  mercury  from  their  solutions,  converting  ferric  and  cupric 
into  ferrous  and  cuprous  salts,  and  partially  deoxidizing  arsenic, 
manganic,  and  chromic  acids.  It  absorbs  oxygen  from  the  air,  and  is 
decomposed  when  added  to  a large  quantity  of  water  unless  some  acid 
be  present.  It  is  used  as  a mordant  in  dyeing  and  calico-printing. 

Perchloride  of  Tin.  Stannic  Chloride. 

Second  Synthetical  Reaction, — Through  a portion  of  the 
solution  of  the  stannous  chloride  of  the  previous  reaction 
pass  chlorine  gas ; solution  of  stannic  chloride  (SnClJ  is 
formed.  Or  add  hydrochloric  acid  to  the  stannous  solu- 
tion, boil,  and  slowly-  drop  in  nitric  acid  until  no  more 


TIN. 


215 


fumes  are  evolved;  again  stannic  chloride  results.  Reserve 
the  solutions  for  subsequent  experiments. 

Stannic  Oxide,  or  Anhydride,  and  Stannates. 

Third  Synthetical  Beaction, — Boil  a fragment  of  tin  with 
nitric  acid,  evaporate  to  dryness,  and  strongly  calcine  the 
residue  ; white  stannic  anhydride  (SnOg)  is  produced.  Heat 
the  stannic  anhydride  with  excess  of  solid  caustic  potash 
or  soda  ; stannate  of  the  alkali  metal  (K2Sn03  or  Na.^SnOg) 
results.  Dissolve  the  stannate  in  water,  and  add  hydro- 
chloric acid  ; white,  gelatinous  stannic  acid  (H^SnOg)  is 
precipitated.  Stannic  acid  is  also  obtained  on  adding  an 
alkali  to  solution  of  stannic  chloride;  it  is  soluble  in  excess 
of  acid  or  alkali. 

The  product  of  the  action  of  nitric  acid  on  tin  is  also  an  acid,  but 
from  its  insolubility  in  hydrochloric  and  other  acids,  is  different  from 
ordinary  stannic  acid.  It  is  termed  metastannic  acid  (from 
meta,  beyond),  and  probably  has  a composition  expressed  by  the 
formula  H^oSn50i5.  It  is  also  produced  on  gently  heating  stannic 
acid : — 

5H2Sn03  = HjoSn^Oig 
stannic  Metastannic 

acid.  acid. 

Metastannates  maybe  formed;  their  general  formula  is  M2H8Sn50i5. 
Both  acids  yield  buff-colored  stannic  oxide  or  anhydride  (Sn02)  when 
strongly  heated  ; it  is  employed  in  polishing  plate  under  the  name  of 
putty  poivder.  Stannate  of  sodium  (Na2Sn03,4H20)  is  used  as  a 
mordant  by  dyers  and  calico-printers  under  the  name  of  tin  prepare- 
liquor, 

(b)  Beactions  having  Analytical  Interest  ( Tests), 
STANNOUS  SALTS. 

First  Analytical  Beaction. — Through  a solution  of  a 
stannous  salt  (stannous  chloride,  for  example,  see  previous 
page)  pass  sulphuretted  hydrogen;  brown  stannous  sul- 
phide (SnS)  is  precipitated.  Four  off  the  supernatant 
liquid,  add  ammonia  to  the  moist  precipitate  (to  neutralize 
acid),  and  lastly  yellow  sulphydrate  of  ammonium  ; the 
precipitate  is  dissolved. 

Aqueous  solution  of  sulphydrate  of  ammonium  becomes  yellow 
when  a day  or  two  old,  and  then  contains  excess  of  sulphur,  that 
element  having  become  displaced  by  oxygen  absorbed  from  the  air  ; 
hence,  in  the  above  reaction,  the  stannous  sulphide  (SnS),  in  dis- 
solving, becomes  stannic  sulphide  (SnS2) ; for  the  latter  is  precipi- 
tated on  decomposing  the  alkaline  liquid  by  an  acid. 


216 


RAIIER  METALLIC  RADICALS. 


Second  Analytical  Reaction. — To  solution  of  a stannous 
salt  add  solution  of  potash  or  soda ; white  stannous  hydrate 
falls  (Sn2HO).  Add  excess  of  the  alkali ; the  precipitate 
dissolves.  Boil  the  solution  ; some  of  the  tin  is  reprecipi- 
tated as  black  stannous  oxide  (SnO). 

Ammonia  gives  a similar  precipitate,  insoluble  in  excess.  The 
alkaline  carbonates  do  the  same,  carbonic  acid  gas  escaping. 

STANNIC  SALTS. 

Third  Analytical  Reaction, — Through  solution  of  a stan- 
nic salt  (stannic  chloride,  for  example,  see  page  214)  pass 
sulphuretted  hydrogen  gas  ; yellow  stannic  sulphide  (SnS.^) 
is  precipitated.  Pour  off  the  supernatant  liquid,  and  to  the 
moist  precipitate  add  ammonia  (to  neutralize  acid),  and 
then  sulphydrate  of  ammonium  ; the  precipitate  dissolves. 

Note. — In  precipitating  stannic  sulphide  the  presence  of  too  much 
hydrochloric  acid  must  be  avoided  ; the  formation  of  the  precipitate 
is  also  facilitated  if  the  solution  be  warmed.  Stannic  sulphide,  like 
the  sulphide  of  arsenicum  and  antimony,  dissolves  in  a solution  of 
alkaline  sulphide,  with  formation  of  definite  crystallizable  salts. 

Anhydrous  stannic  sulphide,  prepared  by  sublimation,  has  a 
yellow  or  orange  lustrous  appearance,  and  is  used  by  decorators  as 
bronzing-powder.  It  is  sometimes  termed  mosaic  gold. 

Fourth  Analytical  Reaction. — To  solution  of  a stannic 
salt  add  potash  or  soda ; white  stannic  acid  falls  (HaSnOg). 
Add  excess  of  the  alkali ; the  precipitate  dissolves.  Boil 
the  precipitate  ; no  reprecipitation  occurs — a fact  enabling 
stannic  to  be  distinguished  from  stannous  salts. 

Ammonia  gives  a similar  precipitate,  soluble,  but  not  readily,  in 
excess.  The  fixed-alkaline  carbonates  do  the  same,  carbonic  acid 
gas  escaping ; after  a time  the  stannic  salt  is  again  deposited,  pro- 
bably as  stannate  of  the  alkali  metal.  Carbonate  of  ammonium  and 
acid  carbonates  of  alkali  metals  give  a precipitate  of  stannic  acid 
insoluble  in  excess. 

Antidotes. — In  cases  of  poisoning  by  tin  salts  (dyer’s  tin  liquor 
e.  g.),  solution  of  carbonate  of  ammonium  should  be  given.  White  of 
egg  is  also  said  to  form  an  insoluble  precipitate  with  compounds  of 
tin.  Vomiting  should  be  speedily  induced,  and  the  stomach  pump 
quickly  supplied.  fi 

GOLD.  I 

If; 

j 

Source. — Gold  occurs  in  the  free  state  in  nature,  occasionally  in'jj 
nodules  or  nuggets,  but  commonly  in  a finer  state  of  division  termedi  j 
gold  dust.  \i 

ii 


GOLD 


217 


■ 

, Preparation. — Gold  is  sem^ted  from  tlie  sand,  crushed  quartz, 

' or  other  earthy  maj^r  it  may  be  associated,  by  agitation 

' with  water,  when  tl^^old,  from  its  relatively  greater  specific  gravity, 
falls  to  the  bottom  of  the  vessels  first,  the  lighter  mineral  matter 
being  allowed  to  run  off  with  the  water.  From  this  rich  sand  the 
gold  is. dissolved  out  by  mercury,  the  latter  filtered,  and  the  amalgam 
distilled,  when  the  mercury  volatilizes  and  gold  remains.  The  amal- 
1 gamation  may  be  much  facilitated  by  the  use  of  a small  proportion 
of  sodium,  as  described  under  silver. 

Pure  gold  is  too  soft  for  general  use  as  a circulating  medium.  Gold 
coin  is  an  alloy  of  copper  and  gold,  that  of  Great  Britain  containing 
1 of  the  former  to  11  of  the  latter,  or  8^  per  cent,  of  copper,  that  of 
France,  Germany,  and  the  United  States  about  10  per  cent.  Jewel- 
lers^  gold  varies  in  quality^  every  24  parts  containing  18,  15,  12,  or 
9 parts  of  gold,  the  alloys  being  technically  termed  18,  15,  12,  or  9 
carat  fine.  Articles  made  of  the  better  qualities  are  usually  stamped 
by  authority.  Trinkets  of  inferior  intrinsic  worth  are  commonly 
thinly  coated  with  pure  gold  by  electro-deposition  or  otherwise.  Gold 
leafi^  nearly  pure  gold  passed  between  rollers  till  it  is  about  gj-^  of 
an  inch  in  thickness  and  then  hammerecfbetween  sheets  of  animal 
membrane,  termed  gold-beater’s  skin  and  calf-skin  vellum,  till  it  is 
T6?T’(yn?y  or  of  an  inch  in  thickness.  It  may  even  be  hammered 

till  280,000  leaves  would  be  required  to  form  a pile  an  inch  thick. 

Gold  Coinage. — The  weight  of  gold  is  expressed  in  Great  Britain 
in  ounces  troy  and  decimal  parts  of  an  ounce,  and  the  metal  is  always 
taken  to  be  of  standard  fineness  (11  gold  and  1 alloy)  unless  other- 
, wise  described.  The  degree  of  fineness  of  gold,  as  ascertained  by 
assay,  is  expressed  decimally,  fine  pure  gold  gold  free  from  metallic 
impurities,”  B.  P.),  being  taken  as  unity,  or  1.000.  Thus  gold  of 
British  standard  is  said  to  be  0.9166  fine,  of  French  standard  0.900 
fine.  The  legal  weight  of  the  sovereign  is  0.2568  ounce  of  standard 
gold,  or  123.274  grains.  The  weight  came  from  one  pound  of  stand- 
ard gold  (5760  grains)  being  coined  into  44^  guineas.  Gold  coins 
are  legal  tender  to  any  amount,  provided  that  the  weight  of  each 
sovereign  does  not  fall  below  122.5  grains,  or  in  the  case  of  a half 
sovereign  61.125  grains  ; these  are  the  “least  current”  weights  of  the 
coins. 

Note. — In  chemical  analysis  gold  comes  out  among  the  sulphides 
of  the  metals  precipitated  by  sulphuretted  hydrogen ; and  of  those 
sulphides,  it,  like  the  sulphides  of  tin,  antimony,  and  arsenicum,  is 
soluble  in  sulphydrate  of  ammonium. 

Quantivalence. — Gold  is  trivalent  (An”'),  but  in  some  compounds 
univalent  (Au'). 

Reactions. 

Synthetical  Reaction, — Place  a fragment  of  gold  {e. 
gold  leaf)  in  ten  or  twenty  drops  of  aqua  regia  (a  mixture 
of  one  part  of  nitric  and  two  or  three  of  hydrochloric  acid), 
and  set  the  test-tube  aside  in  a warm  place  ; solution  of 
percliloride  of  gold  or  auric  chloride  (AUCI3)  results. 
19 


218 


RARER  METALLIC  RADICALS. 


When  the  metal  is  dissolved,  evaporate  nearly  to  dryness 
to  remove  most  of  the  excess  of  fluid,  dilute  with  water, 
and  retain  the  solution  for  subsequent  experiments.  Sixty 
grains  of  gold  treated  thus,  and  the  resulting  chloride  dis- 
solved in  flve  ounces  of  distilled  water,  constitutes  ‘‘  Solu- 
tion of  Chloride  of  Gold,’’  B.  P. 

Au,  + 2HNO3  + 6HC1  = 2AUCI3  + 2X0  + 4H,0 

This  reaction  has  analytical  interest  also ; for  in  examining  a sub- 
stance suspected  to  be  or  contain  metallic  gold,  solution  would  have 
to  be  effected  in  the  above  way  before  reagents  could  be  applied. 
Gold  is  insoluble  in  hydrochloric,  nitric,  and  the  weaker  acids. 

Analytical  Reactions  {Tests), 

First  Analytical  Reaction, — Through  a few  drops  of  so- 
lution of  an  auric  salt  (the  chloride,  AuClg,  is  the  only 
convenient  one)  pass  sulphuretted  hydrogen  ; brown  auric 
sulphide  (Ail^S3)  is  precipitated.  Filter,  wash,  and  add 
sulphydrate  of  ammonium  ; the  precipitate  dissolves. 

Second  Analytical  Reaction, — To  solution  of  a salt  of 
gold  add  ferrous  chloride  or  sulphate,  and  set  the  tube 
aside ; metallic  gold  is  precipitated,  a ferric  salt  remaining 
in  solution. 

This  is  a convenient  way  of  preparing  pure  gold,  or  fine  gold  as 
it  is  termed,  or  of  working  up  the  gold  residues  of  laboratory  opera- 
tions. The  precipitate,  after  boiling  with  hydrochloric  acid,  washing, 
and  drying,  may  be  obtained  in  a button  by  mixing  with  an  equal 
Aveight  of  borax  or  acid  sulphate  of  potassium  and  fusing  in  a good 
furnace. 

Third  Analytical  Reaction, — Add  a few  drops  of  dilute 
solutions  of  stannous  and  stannic  chloride  to  a consider- 
able quantity  of  distilled  water;  pour  the  liquid,  a small! 
quantity  at  a time,  into  a dilute  solution  of  auric  chloride 
(AuCy,  well  stirring;  the  mixture  assumes  a purple  tint,! 
and  flocks  of  a precipitate,  known  as  the  Purple  of  Cassius,} 
(from  the  name  of  the  discoverer,  M.  Cassius),  are  jiroduced.* 

The  same  compound  is  formed  on  immersing  a piece  of  tin  foil  in  ^ 
solution  of  auric  chloride  ; it  is  said  to  be  a mixture  of  auric,  aurous,  | 
stannic,  and  stannous  oxides.  It  is  the  coloring  agent  in  the  finer 
varieties  of  ruby  glass. 


[ 


PLATINUM. 


219 


PLATINUM. 

Symbol  Pt.  Atomic  weight  198. 

Source. — Platinum,  like  gold,  usually  occurs  in  nature  in  the  free 
state,  the  chief  sources  of  supply  being  Mexico,  Brazil,  and  Siberia. 
It  is  separated  from  the  alluvial  soil  by  washing. 

Uses. — The  chief  use  of  platinum  is  in  the  construction  of  foil,  wire, 
crucibles,  spatulas,  capsules,  evaporating-dishes,  and  stills,  for  the 
use  of  the  chemical  analyst  or  manufacturer.  It  is  tolerably  hard, 
fusible  with  very  great  difficulty,  not  dissolved  by  hydrochloric,  nitric, 
or  sulphuric  acid,  and  only  slightly  affected  by  alkaline  substances. 
It  is  attacked  by  aqua  regia  with  production  of  perchloride  of  plati- 
num or  platinic  chloride  (PtCl^).  It  forms  fusible  alloys  with  lead 
and  other  metals,  and  with  phosphorus  a phosphide,  which  easily 
melts.  Neither  of  these  substances,  therefore,  nor  mixtures  which 
may  yield  a metal,  should  be  heated  in  platinum  vessels. 

The  chemical  position  of  platinum  among  the  elements  is  close 
to  that  of  gold.  Its  atom  is  quadrivalent  in  some  compounds,  in 
others  apparently  bivalent  (Pt").  The  higher  salts  are  termed  j)/a- 
tinic,  the  lower  platinous. 


Reactions. 

Perchloride  of  Platinum.  Platinic  Chloride. 

Synthetical  Reaction, — Place  a fragment  of  platinum  in 
a little  aqua  regia  and  set  the  vessel  aside  in  a warm  place, 
adding  more  acid  from  time  to  time  if  necessary;  solution 
of  perchloride  of  platinum  (PtClJ  results.  Evaporate  the 
solution  to  remove  excess  of  acid,  and  complete  the  desic- 
cation over  a water-bath.  Dissolve  the  residue  in  water  and 
retain  the  solution  for  subsequent  experiments,  and  as  a 
reagent  for  the  precipitation  of  salts  of  potassium  and  am- 
monium. 

A quarter  of  an  ounce  of  platinum  treated  in  the  above  manner, 
and  the  resulting  chloride  dissolved  in  five  ounces  of  water,  consti- 
tutes “Solution  of  Perchloride  of  Platinum,”  B.  P. 

This  reaction  has  analytical  interest  also;  for  in  examining  a sub- 
stance suspected  to  be  or  to  contain  metallic  platinum,  solution  would 
have  to  be  thus  effected  before  reagents  could  be  applied. 

Analytical  Reactions  ( Tests). 

First  Analytical  Reaction. — Through  a few  drops  of  a 
solution  of  a platinic  salt  (PtCl^  is  the  only  convenient  one) 
to  which  an  equal  quantity  of  .solution  of  chloride  of  sodium 
has  been  added,  pass  sulphuretted  hydrogen;  dark  brown 


220 


RARER  METALLIC  RADICALS. 


platinio  sulphide  (PtS.^)  is  precipitated.  Filter,  wash,  and 
add  sulphj'drate  of  ammonium  ; the  precipitate  dissolves. 

If  chloride  of  sodium  be  not  present  in  the  above  reaction,  the  pre- 
cipitated sulphide  will  contain  platinous  chloride,  and  detonate  when 
heated. 

Second  AnoXytical  Reaction, — Add  excess  of  solution  of 
carbonate  of  sodium  and  some  sugar  to  solution  of  per- 
chloride  of  platinum  and  boil ; a precipitate  of  metallic  pla- 
tinum falls. 

Platinum  Black  (B.  P.)  is  the  name  of  this  precipitate.  It  pos- 
sesses in  a high  degree  a quality  common  to  many  substances,  but 
largely  possessed  by  platinum,  namely,  that  of  absorbing  or  occluding 
gases.  In  its  ordinary  state,  after  well  washing  and  drying,  it  ab- 
sorbs from  the  air  and  retains  many  times  its  bulk  of  oxygen.  A 
drop  of  ether  or  alcohol  placed  on  it  is  rapidly  oxidized,  the  plati- 
num becoming  hot.  This  action  may  be  prettily  shown  by  pouring 
a few  drops  of  ether  into  a beaker  (one  having  portions  of  the  top 
and  sides  broken  off  answers  best),  loosely  covering  the  vessel  with 
a card,  and  suspending  within  the  beaker  a platinum  wire,  one  end 
being  attached  to  the  card  by  passing  through  its  centre,  the  other 
terminating  in  a short  coil  or  helix  near  the  surface  of  the  ether ; on 
now  warming  the  helix  in  a flame  and  then  rapidly  introducing  it 
into  the  beaker,  it  will  become  red-hot  and  continue  to  glow  so  long 
as  there  is  ether  in  the  vessel.  In  this  experiment  real  combustion 
goes  on  between  the  ether  vapor  and  the  concentrated  oxygen  of 
the  air,  the  products  of  the  oxidation  revealing  themselves  by  their 
odor. 

Third  Analytical  Reaction, — To  solution  of  perchloride 
of  platinum  add  solution  of  chloride  of  ammonium  ; a yel- 
low granular  precipitate  of  double  chloride  of  platinum  and 
ammonium  (PtCl^,  2AmCl)  falls.  When  slowly  formed  in 
dilute  solutions,  the  precipitate  is  obtained  in  minute  orange 
prisms. 

Chloride  of  potassium  (KOIJ  gives  a similar  precipitate  (PtCh 
2KC1).  Platinic  chloride  having  been  stated  to  be  a test  for  potas- 
sium and  ammonium  salts,  the  reader  is  prepared  to  find  that  potas- 
sium and  ammonium  salts  are  tests  for  platinic  salts.  The  double 
sodium  compound  (PtC1^2NaCl)  is  soluble  in  water. 

Collect  tlie  precipitate,  dry,  and  heat  in  a small  crucible  ; 
it  is  decomposed,  and  metal,  in  the  finely  divided  state  of 
spongy  platinum,^  remains. 

3(PtCl,2NII^Cl)  = Pt3  -f  2NII,C1  -f  IGIICI  -f  2'^,. 

Heat  decomposes  the  potassium  salt  into  Pt  -P  2KCl-f-Cl4,  the 
chlorine  escaping  and  the  chloride  of  potassium  remaining  with  the 
platinum. 


C A D M I U xM . 


221 


In  working  up  the  platinum  residues  of  laboratory  operations, 
the  mixture  should  be  dried,  burnt,  boiled  successively  with  hydro- 
chloric acid,  water,  nitric  acid,  water,  then  dissolved  in  aqua  regia, 
excess  of  acid  removed  by  evaporation,  chloride  of  ammonium  added, 
the  precipitate  washed  with  water,  dried,  ignited,  and  the  resulting 
spongy  platinum  retained  or  converted  into  perchloride  for  use  as  a 
reagent  for  alkali-metals.  It  is  by  this  process  that  the  native  pla- 
tinum is  treated  to  free  it  from  the  rare  metals  palladium,  rhodium, 
osmium,  ruthenium,  and  iridium.  The  spongy  platinum  is  converted 
into  the  massive  condition  by  a refinement  on  the  blacksmith’s  pro- 
cess of  welding  (German  wellen,  to  join),  or  by  fusing  in  a flame  of 
pure  oxygen  and  hydrogen  gases — the  oxyhydrogen  blowpipe. 

Occlusion  by  Spongy  Platinum. — Spongy  platinum  has  great 
power  of  occlusion.  A small  piece  held  in  a jet  of  hydrogen  causes 
ignition  of  the  gas,  owing  to  the  close  approximation  of  particles  of 
oxygen  (from  the  air)  and  hydrogen.  Dobereiner’s  lamp  is  con- 
structed on  this  principle — the  apparatus  being  essentially  a vessel 
in  which  hydrogen  is  generated  by  the  action  of  diluted  sulphuric 
acid  on  zinc,  and  a cage  for  holding  the  spongy  platinum. 

CADMIUM. 

Symbol  Cd.  Atomic  weight  112. 

In  most  of  its  chemical  relations  cadmium  ( Cadmium,  U.  S.  P.)  re- 
sembles zinc.  In  nature  it  occurs  chiefly  as  an  occasional  constituent 
of  the  ores  of  that  metal.  In  distilling  zinc  containing  cadmium, 
the  latter,  being  the  more  volatile,  passes  over  first.  In  analytical 
operations  cadmium,  unlike  zinc,  comes  down  among  the  metals  pre- 
cipitated by  sulphuretted  hydrogen  ; that  is,  its  sulphide  is  insoluble 
in  dilute  hydrochloric  acid,  while  sulphide  of  zinc  is  soluble.  It  is  a 
white  malleable  metal  nearly  as  volatile  as  mercury.  Sp.  gr.  8.7. 

Beyond  the  occasional  employment  of  the  sulphide  as  a pigment 
ijaune  brillant).  and  the  iodide  in  photography  and  medicine,  cad- 
mium and  its  salts  are  but  little  used.  The  atom  of  cadmium  is 
bivalent  (Cd"). 


Reactions. 

Iodide  of  Cadmium. 

First  Synthetical  Reaction. — Digest  metallic  cadmium  in 
water  in  which  a fragment  of  iodine  is  placed,  until  the 
color  of  the  iodine  disappears ; solution  of  iodide  of  cad- 
mium (Gadmii  lodidum^  B.  P.)  (Cdl2)  remains.  Pearly 
micaceous  crystals  may  be  obtained  on  evaporating  the 
solution. 

This  is  the  process  alluded  to  in  the  British  Pharmacopoeia.  The 
compound  is  used  in  medicine  in  the  form  of  ointment,  tfnguentum 
Cadmii  lodidi,  B.  P.  The  salt  is  also  employed,  with  other  iodides, 

19* 


222 


RARER  METALLIC  R A P I C A L S . 


in  iodizing  collodion  for  photographic  purposes.  It  melts  when 
heated,  and  is  soluble  in  water  or  spirit,  the  solution  reddening  litmus 
paper. 


Sulphate  of  Cadmium. 

Second  Synthetical  Reaction, — Dissolve  cadmium  in  nitric 
acid;  pour  the  resulting  solution  of  nitrate  of  cadmium 
(Cd2N03)  into  a solution  of  carbonate  of  sodium  ; dissolve 
the  precipitate  of  carbonate  of  cadmium  (CdCOg)  in  dilute 
sulphuric  acid,  separate  and  crystallize.  Sulphate  of  cad- 
mium (CdSOj  is  a white  crystalline  salt  soluble  in  water, 
(U.  S.  P.). 

First  Analytical  Reaction, — Through  solution  of  a cad- 
mium salt  (Cdl2  or  CdCl,^)  pass  sulphuretted  hydrogen;  a 
3^ellow  precipitate  of  sulphide  of  cadmium  (CdS)  falls,  re- 
sembling in  appearance  arsenious,  arsenic,  and  stannic 
sulphides.  Add  sulphydrate  of  ammonium  ; the  precipitate, 
unlike  the  sulphides  just  mentioned,  does  not  dissolve. 

Sulphides  of  cadmium  and  copper  may  be  separated  by  solution  of 
cyanide  of  potassium,  in  which  sulphide  of  copper  is  soluble  and 
sulphide  of  cadmium  insoluble. 

Second  Analytical  Reaction, — To  a cadmium  solution  add 
solution  of  potash;  white  hydrate  of  cadmium  (Cd2HO) 
is  precipitated,  insoluble  in  excess  of  the  potash. 

Hydrate  of  zinc  (Zn2HO),  precipitated  under  similar  circum- 
stances, is  soluble  in  solution  of  potash  ; the  filtrate  from  the  hydrate 
of  cadmium  may  therefore  be  tested  for  any  zinc  occurring  as  an 
impurity  by  applying  the  appropriate  reagent — sulphydrate  of  am- 
monium. 

Before  the  blowpipe- fiame,^  on  charcoal,  cadmium  salts 
give  a brown  deposit  of  oxide  of  cadmium  (CdO). 

BISMUTH. 

Symbol  Bi.  Atomic  weight  208. 

Source. — Bismuth  occurs  in  the  metallic  state  in  nature.  It  is 
freed  from  adherent  quartz,  etc.,  by  simply  heating,  when  the  metal 
melts,  runs  off,  and  is  collected  in  appropriate  vessels.  It  is  also  met 
with  in  combination  with  other  elements.  Bismuth  is  grayish-white, 
with  a distinct  pinkish  tinge. 

Uses. — Beyond  the  employment  of  some  of  its  compounds  in  medi- 
cine, bismuth  is  but  little  used.  Melted  bismuth  expands  considerably 
on  solidifying,  and  hence  is  valuable  in  taking  sharp  impressions  of 
dies.  It  is  a constituent  of  some  kinds  of  type-metal  and  of  pewter- 
solder. 


BISMUTH. 


223 


The  position  of  bismuth  among  the  metals  is  close  to  that  of  arse- 
nicum  and  antimony.  ‘ Its  atom  is  rarely  quinquivalent  (Bi’^) ; but 
in  most  compounds  trivalent  (Bi'"). 

Reactions  having  (a)  Synthetical  and  (6)  Analytical 
Interest. 

(a)  Reactions  having  Synthetical  Interest, 

Nitrate  of  Bismuth. 

First  Synthetical  Reaction, — To  a few  drops  of  nitric  acid 
and  an  equal  quantity  of  water  in  a test-tube,  add  a little 
powdered  bismuth,  heating  the  mixture  if  necessary;  nitric 
oxide  (NO)  escapes,  and  solution  of  nitrate  of  bismuth 
(BiSNOg)  results. 

Bi,  + 8HNO3  = 2(Bi3N03)  + 2NO  + 

Bis-  Nitric  acid.  Nitrate  of  Nitric  Water. 

muth.  bismuth.  oxide. 

The  solution  evaporated  gives  crystals  (BiSNO^,  5H^O),  any  arse- 
nicum  which  the  bismuth  might  contain  remaining  in  the  mother- 
liquor.  Native  bismuth  [Bismuthum,  B.  P.  and  U.  S.  P.)  commonly 
contains  arsenicum,  most  of  which  is  removed  by  roasting  or  by  fus- 
ing two  or  three  times  with  a tenth  of  its  weight  of  nitre  [Bismuthum 
Purificatum,  B.  P.),  or,  finally,  by  converting  the  metal  into  oxyni- 
trate,  as  described  in  the  next  reaction,  and  reducing  this  with  char- 
coal at  a high  temperature. 

To  make  nitrate  of  bismuth  and  other  salts  on  a larger  scale, 
2 ounces  of  the  metal,  in  small  fragments,  are  gradually  added  to  a 
mixture  of  4 fluidounces  of  nitric  acid  and  3 of  water,  and,  when 
effervescence  (due  to  escape  of  nitric  oxide)  has  ceased,  the  mixture 
heated  for  ten  minutes,  poured  off  from  any  insoluble  matter,  eva- 
porated to  2 fluidounces  to  remove  excess  of  acid,  and  then  either  set 
aside  for  crystals  to  form,  poured  into  half  a gallon  of  water  to  form 
the  oxynitrate  of  bismuth,  or  into  a solution  of  6 ounces  of  carbonate 
of  ammonium  in  a quart  of  water  to  form  the  oxycarhonate  as  de- 
scribed in  the  following  reactions.  The  precipitates  should  be  washed 
with  cold  water  and  dried  at  a temperature  not  exceeding  150°  F. 
Exposed  in  the  moist  state  to  212°  for  any  length  of  time,  they 
undergo  slight  decomposition. 

Subnitrate  or  Oxynitrate  of  Bismuth. 

Second  Synthetical  Reaction, — Pour  some  of  the  above 
solution  into  a considerable  quantity  of  water ; decompo- 
sition occurs  and  oxynitrate  of  bismuth  (BiONO.^)  in  a 
hydrous  state  (Bi0N03,  H^O)  {Bismuthi  Suhnitras^  B.  P.) 
is  precipitated : — 

Bi3N03  + = Bi0N03  + 2HNO3 

Nitrate  of  Water.  Oxynitrate  of  Nitric  acid. 

bismuth.  bismuth. 


224 


RARER  METALLIC  RADICALS. 


Filter,  and  test  the  filtrate  for  bismuth  by  adding  excess 
of  carbonate  of  sodium;  a precipitate  shows  that  some 
bismuth  remains  in  solution.  The  following  equation, 
therefore,  probably  more  nearly  represents  the  decompo- 
sition : — 

5(Bi3N03)  -f  8H,0  = 4(Bi0N03,  H,0)  + Bi3N03,8HN03 

Nitrate  of  Water.  Oxy  nitrate  of  Nitrate  of  bismuth 

bismuth.  bismuth.  iu  acid. 

Decomposition  of  nitrate  of  bismuth  by  water  is  the  process  of  the 
British  Pharmacopoeia  for  the  preparation  of  oxynitrate  or  “sub- 
nitrate”  of  bismuth  for  use  in  medicine.  For  this  purpose  the 
original  metal  must  contain  no  arsenicum.  In  manufacturing  the 
compound,  therefore,  before  pouring  the  solution  of  nitrate  into 
water,  the  liquid  should  be  tested  for  arsenicum  by  one  of  the  hydro- 
gen tests  ; if  that  element  be  present,  the  solution  must  be  evaporated 
and  only  the  deposited  crystals  be  used  in  the  preparation  of  the 
oxynitrate.  For  on  pouring  an  arsenical  solution  of  nitrate  of  bis- 
muth into  water,  the  arsenicum  is  not  wholly  removed  in  the  super- 
natant liquid,  unless  the  oxynitrate  be  redissolved  and  reprecipitated 
several  times,  according  to  the  amount  of  arsenicum  present. 

In  the  United  States  Pharmacopoeia  the  solution  of  nitrate  (made 
from  washed  carbonate)  is  directed  to  be  poured  into  dilute  solution 
of  ammonia.  Such  a product  will  probably  contain  more  oxhydrate 
than  oxynitrate. 

Suhnitrate  of  Bismuth  is  sometimes  administered  in  the  form  of 
a lozenge  {Trochisci  Bismuthi,  B.  P.).  It  is  used  as  a cosmetic 
under  the  name  of  Fearl-ivhite  {Blanc  de  Perle). 

Oxy  salts  of  Bismuth. — It  will  be  noticed  that  the  formula  for 
subnitrate  of  bismuth  (BiNO^)  does  not  accord  with  that  of  other 
nitrates,  the  characteristic  elements  of  which  are  NO^.  Analogy 
would  seem  to  indicate,  however,  that  the  fourth  atom  of  oxygen  has 
different  functions  to  the  three  in  the  NO3;  for  on  pouring  solution 
of  chloride  of  bismuth  (BiCb)  into  water,  oxychloride  is  produced 
(BiOCl)  (a  white  powder  used  as  a cosmetic,  also  in  enamels,  and  in 
some  varieties  of  sealing-wax).  The  bromide  (BiBrg)  and  iodide 
(Bilg)  similarly  yield  oxybromide  (BiOBr)  and  oxyiodide  (BiOI). 
The  subnitrate  (BiN04)  is,  therefore,  probably  an  analogous  com- 
pound, an  oxynitrate  (BiONOg).  The  sulphate  (Bi23S04)  also  de- 
composes when  placed  in  water,  giving  what  may  be  termed  an 
oxysulphate  (Bi202S04). 

It  is  difficult  to  prove  whether  or  not  the  water  in  the  “subni- 
trate” or  hydrous  oxynitrate  of  bismuth  (BiONOg,  II.^O)  is  an  inte- 
gral part  of  the  salt.  If  it  is,  the  compound  is  simply  the  hydrato- 
nitrate  (BiNOg2HO)  of  bismuth. 

Subcarbonate  or  Oxycarbonate  of  Bismuth. 

Thii'd  Synthetical  Reaction, — To  solution  of  nitrate  of 
bismuth  add  carbonate  of  ammonium  ; ^white  precipitate 


BISMUTH. 


225 


of  hydrous  oxycarbonate  (2Bi202C03,  HgO)  (Bisniuihi  Gar- 
honas^  B.  P.)  falls. 

4(Bi3N03)  + = 12NH,N03  + 

Nitrate  of  “ Carbonate”  of  Nitrate  of 

bismuth.  ammonium.  ammonium. 

+ too. 

Carbonic 
acid  gas. 

According  to  the  United  States  Pharmacopoeia  the  0x3^- 
carbonate  (Bismuthi  Subcarbonas)  is  made  by  precipitating 
with  carbonate  of  sodium  a solution  of  the  nitrate  prepared 
from  washed  hydrate  of  bismuth. 

This  compound  may  be  regarded  as  similar  in  constitution  to  the 
oxysaltsjust  described.  luBi^COg  one  scarcely  recognizes  the  char- 
acteristic elements  of  carbonates ; but  considering  the  preparation 
to  be  an  oxycarbonate  (Bi202C03)  its  relations  to  carbonates  and 
oxides  are  evident.  These  subsalts  may  all  be  viewed  as  normal 
bismuth  salts  in  which  an  atom  of  oxygen  replaces  an  equivalent 
proportion  of  other  acidulous  atoms  or  radicals  : — 


Chloride Bi3Cl  Oxychloride  . BiOCl 

Bromide BiSBr  Oxybromide  . BiOBr 

Iodide Bi3I  Oxyiodide  . . BiOI 

Nitrate Bi3N03  Oxynitrate  . BiONOg 

Sulphate Bi23SO^  Oxysulphate  . Bi202S0^ 


Carbonate  (unknown)  BigSCOg  Oxycarbonate  Bi202C03 

They  may  be  viewed,  in  short,  as  salts  in  process  of  conversion  to 
oxide ; continue  the  substitution  a little  further,  and  each  yields 
oxides  of  bismuth  (Bi203).  They  have  also  been  considered  to  be 
salts  of  a hypothetical  univalent  radical  bismuthyl  (BiO). 

Citrate  of  Bismuth. 

Fourth  Synthetical  Reaction. — To  solution  of  nitrate  of 
bismuth  add  citric  acid  and  then  solution  of  ammonia  until 
the  precipitate  at  first  formed  is  redissolved,  and  the  liquid 
after  shaking  has  a slight  ammoniacal  odor.  The  product 
contains  citrate  of  bismuth  (BiCgH^O.,  H^O  ?)  dissolved  in 
solution  of  citrate  and  nitrate  of  ammoniu-m.  Made  with 
definite  quantities  of  ingredients  and  an  amount  of  bismuth 
salt  equivalent  to  the  three  grains  of  oxide  (Bi203)  in  a 
fluidrachm,  the  solution  forms  the  Liquor  Bismuthi  et  Am- 
monise  Citratis.^  B.  P. 

(b)  Reactions  having  Analytical  Interest  ( Tests). 

First  AnalyticcRr-Reaction. — Through  solution  of  a bis- 
muth salt  (a  slightly  acid  solution  of  nitrate,  for  example) 


2Bi202C03 

Oxycarbonate 
of  bismuth. 


226 


RARER  METALLIC  RADICALS. 


pass  siilpliu retted  hydrogen  ; a black  precipitate  of  sulphide 
of  bismuth  falls.  Add  ammonia  (to  neutralize  acid) 

and  then  sulphydrate  of  ammonium  ; the  precipitate,  unlike 
As^^Sg  and  Sb.^Sg,  is  insoluble. 

Second  Analytical  Reaction. — Concentrate  almost  any 
acid  solution  of  a bismuth  salt  and  pour  into  water  ; a 
white  salt  is  precipitated. 

This  reaction  is  characteristic  of  bismuth  salts ; it  has  already 
been  amply  explained.  The  precipitate  is  distinguished  from  one 
formed  by  antimony  under  similar  circumstances,  by  being  insoluble 
in  solution  of  tartaric  acid. 


The  reader  is  again  advised  to  trace  out  the  exact  nature  of  each 
of  the  foregoing  reactions,  chiefly  by  aid  of  equations  or  diagrams. 


QUESTIONS  AND  EXERCISES. 

343.  Enumerate  the  fifteen  metals,  salts  of  which  are  frequently 
employed  in  pharmacy. 

344.  Mention  the  eleven  rarer  metals. 

345.  Name  the  sources  and  official  compounds  of  lithium. 

346.  Give  an  equation  explanatory  of  the  formation  of  Citrate  of 
Lithium. 

347.  What  is  the  strength  of  Liquor  Litliice  Effervescens  f 

348.  On  what  chemical  hypothesis  are  lithium  compoufids  admi- 
nistered to  gouty  patients  ? 

349.  Describe  the  relation  of  lithium  to  other  metals. 

350.  What  is  the  chief  test  for  lithium  ? 

351.  Write  a paragraph  on  strontium,  its  natural  compounds, 
chemical  relations,  technical  applications,  and  tests. 

352.  What  are  the  formulae  and  properties  of  oxalate  of  cerium  ? 

353.  Name  the  commonest  ore  of  manganese,  and  give  an  equation 
descriptive  of  its  reaction  with  hydrochloric  acid. 

354.  Explain  the  formation  of  permanganate  of  potassium,  employ- 
ing diagrams  or  equations. 

355.  In  what  manner  do  the  manganates  of  potassium  act  as  dis- 
infectants ? 

356.  What  are  the  chief  tesW^r  manganese  ? 

357.  What  are  the  chief  use?^  the  compounds  of  cobalt  ? 

358.  IIow  are  salts  of  cobalt  analytically  distinguished  from  those 
of  nickel  ? 

359.  Mention  an  application  of  nickel  in  the  arts. 

360.  What  is  the  general  color  of  nickeL^^alts  ? 

361.  State  the  method  of  preparation  of  red  chromate  of  potassium. 

362.  Give  the  formulae  of  red  and  yellow  chromates  of  potassium. 

363.  How  is  red  chromate  of  potassium  obtained  ? 


QUESTIONS  AND  EXERCISES. 


227 


364.  Describe  the  action  of  sulphuretted  hydrogen  on  acidified 
solutions  of  chromates. 

365.  What  is  the  formula  of  chrome  alum  ? 

366.  Mention  the  chief  tests  for  the  chromic  radical,  and  for  chro- 
mium. 

367.  How  would  you  detect  iron,  chromium,  and  aluminium  in  a 
solution  ? 

368.  Define  the  terms  tinstone,  stream-tin,  block-tin,  grain-tin,  tin- 
plate. 

369.  Describe  the  position  occupied  by  tin  in  relation  to  other 
metals. 

370.  What  is  the  difference  between  stannic  acid  and  metastannic 
acid  ? 

371.  State  the  applications  of  tin  in  the  arts. 

372.  Mention  the  chief  tests  for  stannous  and  stannic  salts. 

373.  Name  the  best  antidote  in  cases  of  poisoning  by  tin  solutions. 

374.  How  is  gold  dust  separated  from  the  earthy  matter  with 
which  it  is  naturally  associated? 

375.  How  much  pure  gold  is  contained  in  English  coin,  and  in 
jewellers’  gold  ? 

376.  State  the  average  thickness  of  gold  leaf. 

377.  What  is  the  weight  of  a sovereign  ? 

378.  Explain  the  term  ‘‘fineness”  as  applied  to  gold. 

379.  What  effect  is  produced  on  gold  by  hydrochloric,  nitric,  and 
nitrohydrochloric  acids  respectively  ? 

380.  By  what  reagents  is  metallic  gold  precipitated  from  solutions 
of  its  salts  ? 

381.  How  is  Purple  of  Cassius  prepared  ? 

382.  Whence  is  platinum  obtained  ? 

383.  Why  are  platinum  utensils  peculiarly  adapted  for  use  in  che- 
mical laboratories  ? 

384.  How  is  perchloride  of  platinum  prepared  ? - 

385.  Name  the  chief  tests  for  platinum. 

386.  What  is  “platinum  black”? 

387.  Describe  an  experiment  demonstrative  of  the  large  amount 
of  attraction  for  gases  possessed  by  metallic  platinum. 

388.  How  is  “ spongy  platinum”  produced  ? 

389.  By  what  process  may  the  metal  be  recovered  from  platinum 
residues  ? 

390.  What  is  occlusion  in  chemistry? 

391.  In  what  condition  does  cadmium  occur  in  nature  ? 

392.  By  what  process  may  Iodide  of  Cadmium  be  prepared  ? and 
in  what  form  is  it  used  in  medicine^ 

393.  Mention  the  chief  test  for  fcil^iium. 

394.  Distinguish  sulphide  of  cadmium  from  other  sulphides  of 
similar  color.  * 

395.  How  is  cadmium  separated  from  zinc  ? 

396.  How  does  bismuth  ocmir  in  nature  ? 

397.  What  is  the  quantivalence  of  bismuth  ? 

398.  Write  down  equations  descriptive  of  the  action  of  nitric  acid 
on  bismuth,  and  water  on  nitrate  of  bismuth. 


228 


RARE«,  METALLIC  RADICALS. 


399.  How  may  pure  salts  be  prepared  from  bismuth  containing 
arsenicum  ? 

400.  Give  a diagram  of  the  process  for  the  so-called  Carbonate  of 
Bismuth. 

401.  Write  formulae  showing  the  accordance  of  the  official  Subni- 
trate and  Carbonate  with  the  other  salts  of  Bismuth,  and  with  or- 
dinary Nitrates  and  Carbonates. 

402.  How  is  Liquor  Bismuthi  et  Ammonice  Citratis  prepared  ? 

403.  What  are  the  tests  for  Bismuth? 

Practical  Analysis. 

Bismuth  is  the  last  of  the  metals  whose  synthetical  or  analytical 
relations  are  of  general  interest.  The  position  of  the  rarer  among 
the  common  metals,  and  the  influence  which  either  has  on  the  other 
during  the  manipulations  of  analysis,  will  now  be  considered.  These 
objects  will  be  best  accomplished,  and  a more  intimate  acquaintance 
wdth  all  the  metals  be  obtained,  by  analyzing,  or  studying  the  methods 
of  analyzing,  solutions  containing  one  or  more  metallic  salts. 

Of  the  following  4'ables,  the  first  (1)  includes  directions  for  the 
analysis  of  an  aqueous  or  only  slightly  acid  solution  containing  but 
one  salt  of  any  of  the  metals  hitherto  considered.  Here  the  color  of 
the  precipitate  or  precipitates  afforded  by  a metal  under  given  cir- 
cumstances must  be  relied  on  to  a considerable  extent  in  attempting 
the  detection  of  the  various  elements. 

The  second  Table  (2)  is  intended  as  a chart  for  the  analysis  of 
solutions  containing  salts  of  more  than  one  of  the  common  and  rarer 
metals.  It  is  simply  a compilation  from  the  foregoing  reactions — an 
extension  of  the  scheme  for  the  analysis  of  salts  of  the  ordinary 
metals.  Hence  it  often  may  be  altered  or  varied  in  arrangement  to 
suit  the  requirements  of  the  analyst. 

The  third  (3)  is  a mere  outline  of  the  preceding  Tables.  It  gives 
the  position  of  the  metals  in  relation  to,each  other,  and  will  much  aid 
the  memory  in  recollecting  that  relation. 


2)  OF  SHORT  DIRECTIONS  FOR  APPLYING  SOME  OF  THFFOR 


iiydrocliloric  acid. 


)F 


Precipitate 
Hg(bus)  Pb  Ag. 
boil  with  water,  filter. 


recipilate 
Hg  Ag. 

, add  AmHO. 
5L 


Filtrate 

Ag. 

AddHNOs. 
White  ppt. 


See  also  p.  231. 


Filtrate 

Pb. 

Add  H2SO4. 
White  ppt. 


» c 

Cu 

Precipii 

te 

Cd  Cu  Ag  Pb 

As 

Collect, 

wash,  digest 

in  A 

Precipitate 

Cd 

Cu  Hg  Pb  Bi. 

Wash,  boil  in  H^Os,  filter. 

■'a 

(idi] 

Ppt. 

Filtrate 

Hg. 

Cd  Cu 

Pb  Bi. 

sol.  ■ 

Black. 

Add  AmHO.  filter. 

IS. 

Confirm 

Y 

llo\\ 

by  Cu 

iSrn 

test  in 

Precipitate 

Filtrate 

hS 

Flei 

original 

Pb  Bi. 

Cd 

Cu 

m 

un’i“ 

solution. 

Wash, 

add  a few 

Add  KCy  and 

8t. 

drops  HNO3, 

ILS. 

- 

dilute,  filter. 

n 

Ppt. 

Filt. 

Ppt. 

Filt. 

Bi. 

Pb. 

Cd. 

Cu 

At 

ape  ^ 

Dilute, 

Yellow 

Acidify 

add 

with 

1 

H,S04, 

HC3H3O3 

:i 

set  aside ; 

Brown 

X 

white 

ppt. 

ppt. 

* 

See  also  p.  232. 

^ 

Jr 

1 

J 

I 


ANALYTICAL  CHART  FOR  METALS.  229 


230 


RARER  METALLIC  RADICALS. 


3.  OUTLINE  OF  THE  PRECEDING  TABLES. 


HCl 

H^S 

AmHS 

Am^COg 

Am  JIAsO^ 

Hg 

Cd  I 

Zn  1 

d 

Ba 

Mg 

K 

(as  mercurous 

g 

salt) 

Cu 

<£3 

Pb 

(some) 

Hg 

a 

<£5 

Mn 

d 

® 

3 

d 

Sr 

Na 

(as  mer- 
curic 
salt) 

d 

2 

Co 

' 3 

oc 

Ca 

Am 

d 

Ag 

Pb  , 

o 

ra 

d 

3 

(a  little) 

Ni 

Bi 

As 

A1  ' 

d 

(as  arse- 

B 

nious  or 

< 

L 

arsenic 

o 

salt) 

Fe 

Sb 

CO 

K 

1 

1 

a 

Sn 

(as  stan- 
nous or 

® 

3 

Cr  , 

3 

£ 

stannic 

d 

salt) 

3 

03 

All 

Pt 

The  laboratory  student  should  practise  the  examination  of  aqueous 
solutions  of  salts  of  the  above  metals  until  able  to  analyze  with  facility 
and  accuracy. 


Memoranda  relating  to  the  preceding  Analytical  Tables. 
General  Memoranda. 


These  charts  are  constructed  for  the  analysis  of  salts  more  or  less 

soluble  in  water. The  student  has  still  to  laarlTlfB^^  substances 

insoluble  in  water  are  to  be  brought  into  a state  of  solution;  but  once 
'H'  dissolved,  their  analysis  is  effected  by  the  same  scheme  as  tlnix  just 
^ given.  The  second  Table  may  therefore  be  regarded  as  fairly  jepre- 
'senting  the  method  by  which  metallic  constituents  of  chemical  Vib- 
are  separated  from  each  other  and  recognized. The 


ANALYTICAL  MEMORANDA. 


231 


metliods  of  isolation  of  the  complementary  constituent  of  the  salt 
(the  reactions  of  non-metals  and  acidulous  radicals)  will  form  the 
next  object  of  practical  study. 

The  group-tests  adopted  in  the  Tables  are,  obviously,  hydrochloric 
acid,  sulphuretted  hydrogen,  sulphydrate  of  ammonium,  carbonate  of 
ammonium,  and  arseniate  of  ammonium.  If  a group-test  produces 
no  precipitate,  it  is  self-evident  that  there  can  be  no  member  of  the 
group  present.  At  first,  therefore,  add  only  a small  quantity  of  a 
group-test,  and  if  it  produces  no  effect  add  no  more ; for  it  is  not 
advisable  to  overload  a solution  with  useless  reagents ; substances 
expected  to  come  down  as  precipitates  are  not  unfrequently  held  in 
the  liquid  by  excess  of  acid,  alkali,  or  strong  aqueous  solution  of 
some  group  reagent,  thoughtlessly  added.  Indeed,  experienced  mani- 
pulators not  unfrequently  make  preliminary  trials  with  group-reagents 
on  a few  drops  only  of  the  liquid  under  examination  ; if  a precipitate 
is  produced,  it  is  added  to  the  bulk  of  the  original  liquid  and  the 
addition  of  the  group-reagent  continued ; if  a precipitate  is  not  pro- 
duced, the  few  drops  are  thrown  away  and  the  unnecessary  addition 
of  a group-reagent  thus  avoided  altogether,  an  advantage  fully 

making  up  for  the  extra  trouble  of  making  a preliminary  trial. 

While  shunning  excess,  however,  care  must  be  taken  to  avoid  defi- 
ciency ; a substance  only  partially  removed  from  solution  through 
the  addition  of  an  insufficient  amount  of  a reagent  will  appear  where 
not  expected,  be  consequently  mistaken  for  something  else,  and 
cause  much  trouble ; this  will  not  occur  if  the  appearance,  odor,  or 
reaction  of  the  liquid  on  test-paper  be  duly  observed.  It  is  also  a 
good  plan,  when  a group-reagent  has  produced  a precipitate  and  the 
latter  has  been  filtered  out,  to  add  a little  more  of  the  reagent  to  the 
clear  filtrate  ; if  more  precipitate  is  produced,  an  insufficient  amount 
of  the  group-test  was  introduced  in  the  first  instance ; but  the  error 
is  corrected  by  simply  refiltering ; if  no  precipitate  occurs,  the  mind 
is  satisfied  and  the  way  cleared  for  further  operations. 

Group-precipitates,  or  any  precipitates  still  requiring  examina- 
tion, should,  as  a rule,  be  well  washed  before  further  testing ; this  is 
to  remove  the  aqueous  solution  of  other  substances  adhering  to  the 
precipitate  (the  mother-liquor  as  it  is  termed),  so  that  subsequent 
reactions  may  take  pladb  fairly  between  the  reagent  used  and  the 

precipitate  only. A precipitate  is  sometimes  in  so  fine  a state  of 

division  as  to  retard  filtration  by  clogging  the  pores  of  the  paper,  or 
even  to  pass  through  the  filter  altogether  ; in  these  cases  the  mixture 
may  be  warmed  or  boiled,  which  usually  causes  aggregation  of  the 
particles  of  a precipitate,  and  hence  facilitates  the  passaged  liquids. 

Division  of  Work. — It  is  imm^flerial  whether  a solution  be  first 
divided  into  group-precipitates  or  each  precipitate  be  examined  as 
soon  as  produced;  if  the  former  method  be  adopted,  confusion  will 
be  avoided  by  labelling  or  marking  the  funnels  or  papers  holding 
the  precipitate  “ the  HCl  ppt.,”  “ the  H.^S  ppt.,”  and  so  on. 

The  colors  and  general  appearance  of  the  various  sulphides  and 
hydrates  precipitated  should  be  borne  in  mind,  as  the  absence  of 
other  bodies,  as  well  as  the  presence  of  those  thrown  down,  is  often 
at  once  thus  indicated.  For  example,  if  a precipitate  by.sulphydrate 

f 


232 


THE  METALLIC  RADICALS. 


of  ammonium  is  white,  neither  cobalt,  nickel,  nor  iron  can  be  present, 
and  only  small  quantities  of  manganese  and  chromium. 

Applzcatzons  of  confirmatory  tests  must  be  frequent. 

Results  of  analyses  should  be  recorded  neatly  in  a memorandum- 
book. 

The  various  reactions  which  occur  in  an  analysis  have  already 
come  before  the  reader  in  going  through  the  tests  for  the  individual 
metals  or  in  other  analytical  operations,  it  is  unnecessary,  therefore, 
again  to  draw  out  equations  or  diagrams.  But  the  reactions  should 
be  thought  over,  and,  if  not  perfectly  clear  to  the  mind,  be  written 
out  again  and  again  till  thoroughly  understood. 

Special  Memoranda. 

The  hydrochloric-acid  precipitate  may  at  first  include  some  anti- 
mony and  bismuth  as  oxychlorides,  readily  dissolved,  however,  by 
excess  of  acid. If  either  of  these  elements  be  present  the  wash- 

ings of  the  precipitate  will  probably  be  milky ; in  that  case  add  a 
few  drops  of  hydrochloric  acid,  which  will  clear  the  liquid  and  make 
way  for  the  application  of  the  test  for  lead. 

The  sulphuretted-hydrogen  precipitate  maybe  white,  in  which 
case  it  is  nothing  but  sulphur ; for,  as  already  indicated,  ferric  salts 
are  reduced  to  ferrous,  and  chromates  to  the  lower  salts  of  chromium 
by  sulphuretted  hydrogen,  sulphur  being  deposited: — 

2Fe,Cl6  + 2H2S  = 4FeCl2  + 4HC1  + ; 

4H2CrO,  + 6H2S  + 12H01  = 2Cr,Cl6  + 16H,0  + SS^. 

The  proportion  of  the  sulphuretted-hydrogen  precipitate  dis- 
solved by  sidphydrate  of  ammonium  may  include  a trace  of  copper, 
sulphide  of  copper  being  not  altogether  insoluble  in  sulphydrate  of 

ammonium. On  adding  hydrochloric  acid  to  the  sulphydrate-of- 

ammonium  solution,  a white  precipitate  of  sulphur  only  may  be  pre- 
cipitated, the  sulphydrate  of  ammonium  nearly  always  containing 

free  sulphur. Carbonate  of  ammonium  does  not  readily  dissolve 

small  quantities  of  sulphide  of  arsenicum  out  of  much  sulphide  of 
antimony  ; and,  on  the  other  hand,  carbonate  of  ammonium  takes 
into  solution  a small  quantity  of  sulphide  of  antimony  if  much  sul- 
phide of  arsenicum  is  present.  The  precipftate  or  the  original  solu- 
tion should  therefore  always  be  examined  by  the  other  tests  for  these 
elements  if  any  doubt  exists  concerning  the  presence  or  absence  of 
either.  Tin  remains  in  the  hydrogen-bottle  in  the  metallic  state, 
deposited  as  a black  powder  on  the  zinc  used  in  the  experiment. 
The  contents  of  the  bottle  are  turned  out  into  a dish,  ebullition  con- 
tinued until  evolution  of  hydrogen  ceases,  and  the  zinc  is  taken  up 
by  the  excess  of  sulphuric  acid  employed  ; any  tin  is  then  filtered 
out,  washed,  dissolved  in  a few  drops  of  hydrochloric  acid,  and  the 
liquid  tested  for  tin  by  the  usual  reagents. 

The  portion  of  the  sulphur etteddiydrogen  precipitate  not  dis- 
solved by  the  sulphydrate  of  ammonium  may  leave  a yellow  scrni- 
fused  globule  of  sulphur  on  boiliilg  with  nitric  acid.  This  globule 
may  be  black,  not  only  from  presence  of  mercuric  sulphide,  but  also 
from  inclosed  particles  of  other  sulphides  protected  by  the  sulphur 


ANALYTICAL  MEMORANDA. 


233 


from  the  action  of  the  acid.  It  may  also  contain  sulphate  of  lead, 
produced  by  the  action  of  nitric  acid  on  sulphide  of  lead.  In  cases 
of  doubt  the  mass  must  be  removed  from  the  liquid,  boiled  with 
nitric  acid  till  dissolved,  the  solution  evaporated  to  remove  excess  of 
acid,  and  the  residue  examined ; but  usually  it  may  be  disregarded. 

In  testing  for  lead  by  sulphuric  acid  the  liquid  should  be  diluted 

and  set  aside  for  some  time. 

Mercury  may  also  be  isolated  by  digesting  the  sulphuretted-hydro- 
gen precipitate  in  sulphydrate  of  sodium  instead  of  sulphydrate  of 
ammonium.  The  sulphides  of  arsenicum,  antimony,  tin,  and  mer- 
cury are  thus  dissolved  out.  The  mixture  is  then  filtered,  excess  of 
hydrochloric  acid  added  to  it,  and  the  precipitated  sulphides  collected 
on  a filter,  washed,  and  digested  in  sulphydrate  of  ammonium ; sul- 
phide of  mercury  remains  insoluble,  while  the  sulphides  of  arsenicum, 
antimony,  and  tin  are  dissolved.  By  this  method  copper  also  ap- 
pears in  its  right  place  only,  sulphide  of  copper  being  quite  insoluble 
in  sulphydrate  of  sodium.  The  other  metals  are  then  separated  in 
the  usual  way. 

The  sul])liy  dr  at  e-of -ammonium  precipitate  may,  if  the  original 
solution  was  acid,  contain  Phosphates,  Oxalates,  Silicates,  and  Bo- 
rates of  Barium,  Calcium,  and  Magnesium.  These  will  subsequently 
come  out  with  the  iron,  and,  being  white,  give  the  iron  precipitate  a 
light-colored  appearance  ; their  examination  must  be  conducted  sepa- 
rately, by  a method  described  subsequently  in  connection  with  the 
treatment  of  substances  insoluble  in  water. Precipitates  contain- 

ing aluminium,  iron,  and  chromium  often  carry  down  some  manga- 
nese, which  afterwards  comes  out  with  the  iron.  This  manganese 
may  be  detected  by  w^ashing  the  ferric  hydrate  to  remove  all  trace 
of  chlorides,  boiling  with  nitric  acid,  adding  puce-colored  oxide  .of 
lead,  and  setting  the  vessel  aside;  permanganic  acid  is  formed,  recog- 
nized in  the  clear  liquid  by  its  purple  tint. Sulphide  of  nickel  is 

not  easily  removed  by  filtration  (^vide  p.  209)  until  most  of  the  excess 
of  sulphydrate  of  ammonium  has  been  dissipated  by  prolonged  ebul- 
lition. 

The  carhonate-of -ammonium  precipitate  may  not  contain  the 
whole  of  the  barium,  strontium,  and  calcium  in  the  mixture,  unless 
free  ammonia  be  present;  for  the  carbonates  of  those  metals  are  solu- 
ble in  w^ater  charged  with  carbonic  acid.  If,  therefore,  the  liquid  is 
not  distinctly  ammoniacal,  solution  of  ammonia  should  be  added. 

Neither  carbonate  nor  hydrate  of  ammonium  wholly  precipitates 

magnesian  salts ; and  as  a partial  precipitation  is  undesirable,  a sol- 
vent, in  the  form  of  an  alkaline  salt  (chloride  of  ammonium),  if  not 
already  in  the  liquid,  should  be  added. 

Lithium. — The  search  for  lithium  may  usually  be  omitted.  Should 
a precipitate,  supposed  to  be  due  to  lithium,  be  obtained,  it  must  be 
tested  in  a flame  ( = scarlet  tint),  as  a little  magnesium  not  unfre- 
quently  shows  itself  under  similar  circumstances. 

Spectral  Analysis. — If  present  only  in  minute  proportions,  the 
lithium  may  also  remain  with  the  alkalies;  it  can  then  only  be  de- 
tected by  physical  analysis  (by  a prism)  of  the  light  emitted  from  a 
tinged  flame — by,  in  short,  an  instrument  termed  a spectroscope. 

20* 


234 


THE  METALLIC  RADICALS. 


Such  a method  of  examination  is  called  spectral  analysis,  a subject 
of  much  interest  and  of  no  great  difficulty,  but  scarcely  within  the 
range  of  Pharmaceutical  Chemistry ; it  will  be  briefly  described  in 
connection  with  the  methods  of  analyzing  solid  substances. 


QUESTIONS  AND  EXERCISES. 

404.  Describe  a general  method  of  analysis  by  which  the  metal  of 
a single  salt  in  a solution  could  be  quickly  detected. 

405.  Give  illustrations  of  black,  white,  light  pink,  yellow,  and 
orange  sulphides. 

406.  Mention  the  group-tests  generally  employed  in  analysis. 

407.  Under  wdiat  circumstances  may  a hydrochlonc  precipitate 
contain  antimony  or  bismuth  ? 

408.  If  a sulphuretted-hydrogen  precipitate  is  white,  what  sub- 
stances are  indicated  ? 

409.  Give  processes  for  the  qualitative  analysis  of  liquids  contain- 
ing the  following  substances : — 

a.  Arsenicum  and  Cadmium. 

h.  Bismuth  and  Antimony. 

c.  Ferrous  and  Ferric  salts. 

d.  Aluminium,  Iron,  and  Chromium. 

e.  Arsenicum,  Antimony,  and  Tin. 

f.  Lead  and  Strontium. 

g.  Iron  and  Phosphate  of  Calcium. 

li.  Mercury,  Manganese,  and  Magnesium. 

i.  Zinc,  Manganese,  Nickel,  and  Cobalt. 

j.  Barium,  Strontium,  and  Calcium. 


THE  ACIDULOUS  RADICALS. 


235 


THE  ACIDULOUS  RADICALS. 


Introduction. — The  twenty-six  radicals  which  have  up  to  this 
point  mainly  occupied  attention  are  (admitting  ammonium,  NH^) 
metals ; and  they  have  been  almost  exclusively  studied  not  in  the 
free  state,  but  in  the  condition  in  which  they  exist  in  salts.  Moreover 
these  metals  have  been  treated  as  if  they  formed  the  more  important 
constituent,  the  stronger  half,  the  foundation  or  base,  of  salts.  At- 
tention has  been  continuously  directed  to  the  metallic  or  hasylous 
side  of  salts.  There  is,  indeed,  still  one  more  basylous  radical  worthy 
of  a passing  notice,  though  it  is  usually  supposed  to  play  only  a sub- 
ordinate part  in  reactions — Hydrogen.  Unlike  the  salts  of  most 
metals,  those  of  hydrogen  (the  so-called  acids)  are  never,  in  medicine 
or  the  arts  generally,  professedly  used  for  the  sake  of  their  hydrogen, 
but  always  for  the  other  half  of  the  salt,  the  acidulous  side.  And 
it  is  not  for  their  basylous  radical  that  these  hydrogen  salts  are  now 
commended  to  notice,*  but  in  order  to  study,  under  the  most  favora- 
ble circumstances,  these  acidulous  groupings  which  have  continually 
presented  themselves  in  operations  on  salts,  but  which  were  for  the 
time  of  secondary  importance.  They  may  now  be  treated  as  the  pri- 
mary object  of  attention ; and  there  is  no  better  way  of  doing  so  than 
in  operating  on  their  compounds  with  hydrogen,  the  relatively  infe- 
rior medicinal  importance  of  which  element,  as  compared  with  potas- 
sium, iron,  and  other  basylous  radicals,  will  serve  to  give  the  desired 
prominence  to  the  acidulous  radicals  in  question. 

Common  Acids. — These  salts  of  hydrogen  are  the  ordinary,  sharp, 
sour  bodies  termed  acids  (from  the  Latin  root  acies,  an  edge).  The 
following  Table  includes  the  formulae  and  usual  names  of  the  most 
important ; others  will  be  noticed  subsequently.  A few  of  those  men- 
tioned are  unstable  or  somewhat  rare  ; in  such  cases  a common  me- 
tallic salt  containing  the  acidulous  radical  may  be  used  for  reactions. 

* It  must  not  be  forgotten  that  the  commonest  salt  of  any  radical 
whatsoever  is  a salt  of  hydrogen,  the  oxide  of  hydrogen  (H2O),  or 
hydrate  of  hydrogen  (HHO),  water.  In  the  reactions  already  per- 
formed, the  value  of  this  compound  has  been  constantly  recognized, 
both  for  its  hydrogen  and  for  its  oxygen,  but  most  of  all  as  the  vehicle 
or  medium  by  which  nearly  all  other  atoms  are  enabled  to  come  into 
that  contact  with  each  other  without  which  their  existence  would  be 
almost  useless ; for  some  atoms  are  like  some  animals,  out  of  water 
they  are  as  inactive  as  fishes.  It  is  true  that  both  fishes  and  salts 
have  usually  to  be  removed  from  water  to  be  utilized  by  man  ; but 
before  they  can  be  assimilated,  either  as  food  or  as  medicine,  they 
must  ngain  seek  the  agency  of  water — become  dissolved. 


236 


THE  ACIDULOUS  RADICALS, 


HCl 

hydrochloric  acid. 

HBr 

hydrobromic  acid. 

HI 

hydriodic  acid. 

HCN  (HCy) 

hydrocyanic  acid. 

HNO., 

nitric  acid. 

HClOg 

chloric  acid. 

acetic  acid.* 

H^S 

hydrosulphuric  acid.f 

H^SO. 

sulphurous  acid. 

H^SO; 

sulphuric  acid. 

H.,CO,  ? 

carbonic  acid. 

oxalic  acid. 

H,C,H,0, 

tartaric  acid. 

HsC.H.O, 

citric  acid. 

H.,PO, 

phosphoric  acid. 

H3BO3 

boracic  acid. 

The  old  names  are  here  retained  for  these  acids,  but,  in  studying 
their  chemistry  and  chemical  relations  to  other  salts,  they  are  use- 
fully spoken  of  by  such  more  purely  chemical  names  as  (for  hydro- 
chloric acid)  chloride  of  hydrogen,  (for  nitric  acid)  nitrate  of  hydro- 
gen, and  so  on — sulphate  of  hydrogen,  tartrate  of  hydrogen,  phos- 
phate of  hydrogen. 

A prominent  point  of  difference  will  at  once  be  noticed  between 
the  basylous  radicals  met  with  up  to  the  present  time  and  the  acidu- 
lous groupings  included  in  the  above  tabular  list.  The  former  are 
nearly  all  elements,  ammonium  only  being  a compound;  the  latter 
are  mostly  compounds,  chlorine,  bromine,  iodine,  and  sulphur  being 
the  only  elements.  This  difference  will  not,  however,  be  so  apparent 
when  the  chemistry  of  alcohols,  ethers,  and  such  bodies  has  been  mas- 
tered, for  they  are  all  salts  of  compound  basylous  radicals. 

Rarer  Acids. — The  above  acids  contain  the  only  acidulous  group- 
ings that  commonly  present  themselves  in  analysis,  or  in  pharma- 
ceutical operations.  There  are,  however,  several  other  acids  (such 
as  hypochlorous,  nitrous,  hypophosphorous,  valerianic,  benzoic,  gallic, 
tannic,  uric,  hyposulphurous,  hydroferrocyanic,  hydroferridcyanic, 
and  lactic)  with  which  it  is  desirable  to  be  more  or  less  familiar ; 
reactions  concerning  these  will  therefore  be  described.  Arsenious, 
arsenic,  stannic,  manganic,  and  chromic  acids  have  already  been 

* The  hydrogen  on  the  acidulous  side  must  not  be  confounded  with 
the  basylous  hydrogen  in  all  these  hydrogen  salts  or  acids;  the  two 
pe^rform  entirely  different  functions.  Hydrogen  in  the  acidulous  por- 
tion is  like  the  hydrogen  in  the  basylous  radical  ammonium,  it  has 
combined  with  other  atoms,  to  form  a group  wliich  plays  more  or  less 
the  part  of  an  elementary  radical,  and  to  which  a single  symbol  is  not 
unfrequently  applied  (Am  ; Cy,  A,  0,  T,  C,  etc.).  Cobalt,  chromium, 
iron,  platinum,  etc.,  resemble  hydrogen  in  this  respect  in  often  uniting 
with  other  atoms  to  form  definite  acidulous  radicals,  in  which  the 
usual  basylous  character  of  the  metals  has  for  the  time  disappeared. 
In  hydrides  (p.  105)  hydrogen  itself  is  an  acidulous  radical. 

f Synonyms : sulphydric  acid  and  sulphuretted  hydrogen. 


THE  ACIDULOUS  RADICALS. 


237 


treated  of  in  connection  with  the  metals  they  contain ; in  practical 
analysis  they  always  become  sufficiently  altered  to  come  out  among 
the  metals. 

Quantivalence. — A glance  at  the  foregoing  Table  is  sufficient  to 
show  the  quantivalence  of  the  acidulous  radicals.  The  first  seven 
are  clearly  univalent;  then  follow  six  bivalent,  leaving  three  tri- 
valent. 

These  all  combine  with  equivalent  amounts  of  basylous  radicals  to 
form  various  salts ; hence  they  may  be  termed  monobasylous,  di- 
basylous  and  tribasylous  radicals.  The  acids  themselves  were  for- 
merly spoken  of  as  monobasic,  dibasic,  and  tribasic  respectively,  or 
monobasic  and  polybasic,  in  reference  to  the  amount  of  hase  (hy- 
drates or  oxides)  they  could  decompose  ; but  the  terms  are  no  longer 
definite,  and  hence  but  little  used  in  mineral  chemistry. 

Antidotes. — The  antidotes  in  cases  of  poisoning  by  the  strong 
acids  will  obviously  be  non-corrosive  alkaline  substances,  as  soap 
and  water,  magnesia,  common  washing  “ soda,’’  or  other  carbonates. 
Yinegar,  lemon-juice,  and  weak  or  non-corrosive  acid,  would  be  the 
appropriate  antidotes  to  caustic  alkalies. 

Analysis. — The  practical  study  of  the  acidulous  side  of  salts  will 
occupy  far  less  time  than  the  basylous.  Salts  will  then  be  briefly 
examined  as  a whole. 

One  Word  of  Caution. — It  is  only  for  convenience  in  the  division 
of  chemistry  for  systematic  study  that  salts  maybe  considered  to 
contain  basylous  and  acidulous  radicals,  or  separate  sides,  so  to  speak ; 
for  we  possess  no  absolute  knowledge  of  the  internal  arrangement  of 
the  atoms  (admitting  that  there  are  such  things)  in  the  molecule  of 
a salt.  We  only  know  that  certain  groups  of  atoms  may  be  trans- 
ferred from  compound  to  compound  in  mass  (that  is,  without  apparent 
decomposition) ; hence  the  assumption  that  these  groups  are  radicals. 
A salt  is  probably,  however,  a whole,  having  no  such  ^ides  as  those 
mentioned. 


QUESTIONS  AND  EXERCISES. 

410.  Mention  the  basylous  radical  of  acids. 

411.  Give  illustrations  of  univalent,  bivalent,  and  trivalent  acidu- 
lous radicals,  or  monobasylous,  dibasylous,  and  tribasylous  radicals. 

412.  What  is  the  difference  between  an  elementary  and  a com- 
pound acidulous  radical  ? ^ 

413.  Name  the  grounds  on  which  salts  may  be  assumed  to  contain 
basylous  and  acidulous  radicals. 


238 


SALTS  OF  ACIDULOUS  RADICALS. 


HYDROCHLOmC  ACID  AND  OTHER  CHLORIDES. 

Formula  of  hydrochloric  acid  HCl.  Molecular  weight*  36.5. 

The  acidulous  radical  of  hydrochloric  acid  and  of  other  chlorides 
is  the  element  chlorine  (Cl).  It  occurs  in  nature  chiefly  as  chloride 
of  sodium  (NaCl),  either  solid,  under  the  name  of  rock-salt,  mines 
of  which  are  not  unfrequently  met  with,  or  in  solution  in  the  water 
of  all  seas.  Common  table-salt  is  more  or  less  pure  chloride  of  sodium 
in  minute  crystals. ' Chlorine,  like  hydrogen,  is  univalent  (Cl') ; its 
atomic  weight  is  35.5.  Its  molecule  is  symbolized  thus,  CI2,  chloride 
of  chlorine. 

Reactions. 

Hydrochloric  Acid. 

First  Synthetical  Reaction, — To  a few  fragments  of  chlo- 
ride of  sodium  in  a test-tube  or  small  flask  add  about  an 
equal  weight  of  sulphuric  acid ; colorless  and  invisible 
gaseous  h^^drochloric  acid  is  evolved,  a sulphate  of  sodium 
remaining.  Adapt  to  the  mouth  of  the  vessel,  by  a per- 
forated cork,  a piece  of  glass  tubing  bent  to  a right  angle, 
heat  the  mixture,  and  convey  the  gas  into  a small  bottle 
containing  a little  water;  solution  of  hydrochloric  acid 
results. 

NaCl  + H,SO,  HCl  + NaHSO, 

Chloride  of  Sulphuric  Hydrochloric  Acid  sulphate 

sodium.  acid.  acid.  of  sodium. 

Hydrochloric  Acid. — I'he  product  of  this  operation  is  the  nearly 
colorless  and  very  sour  liquor  commonly  termed  hydrochloric  acid. 
When  of  certain  given  strengths  (estimated  by  volumetric  analysis) 
it  forms  Acidum  Hydrochloricum,  B.  P.  and  Acidum  Muriaticum, 
U.  S.  P.,  and  Acidum  Hydrochloricum  Dilidum,  B.  P.  (and  U.S.  P., 
specific  gr.  1.038).  The  former  has  a specific  gravity  of  1. 16  (1. 1578), 
and  contains  31.8  per  cent,  of  real  acid,  the  latter  specific  gravity 
1.052,  with  10.58  per  cent,  of  real  acid,  and  is  made  by  diluting  8 
fluid  parts  of  the  strong  acid  with  water  until  the  mixture  measures 
26^  fluid  parts.  The  above  process  is  that  of  the  Pharmacopoeias — 
larger  vessels  being  employed,  and  the  gas  being  freed  from  any 
trace  of  sulphuric  acid  by  washing.  Other  chlorides  yield  hydro- 
chloric acid  when  heated  with  sulphuric  acid;  but  chloride  of  sodium 
is  always  used  because  cheap  and  common. 

Common  yellow  hydrochloric  acid  is  a by-product  in  the  manufac- 
ture of  carbonate  of  sodium  from  common  salt,  a process  in  which  the 
chloride  of  sodium  is  first  converted  into  sulphate,  hydrochloric  acid 
being  liberated.  This  impure  acid  is  liable  to  contain  iron,  arsenic, 

* The  weight  of  a molecule  is  the  sum  of  the  weights  of  its  atoms. 


CHLORIDES, 


239 


fixed  salts,  sulphuric  acid,  sulphurous  acid,  nitrous  compounds,  and 
chlorine. 

The  official  (B.  P.)  process  as  follows : — 

‘‘  Take  of  chloride  of  sodium,  dried,  48  ounces,  sulphuric  acid  44 
fluidounces;  water  36  fluidounces,  distilled  water  50  fluidounces;  pour 
the  sulphuric  acid  slowly  into  thirty-two  ounces  of  the  water,  and, 
when  the  mixture  has  cooled,  add  it  to  the  chloride  of  sodium  pre- 
viously introduced  into  a flask  having  the  capacity  of  at  least  one 
gallon.  Connect  the  flask  by  corks  and  a bent  glass  tube  with  a 
three-necked  wash-bottle,  furnished  with  a safety  tube,  and  contain- 
ing the  remaining  four  ounces  of  the  water;  then,  applying  heat  to 
the  flask,  conduct  the  disengaged  gas  through  the  wash-bottle  into  a 
second  bottle  containing  the  distilled  water,  by  means  of  a bent  tube 
dipping  about  half  an  inch  below  the  surface,  and  let  the  process  be 
continued  until  the  product  measures  sixty-six  ounces,  or  the  liquid 
has  acquired  a specific  gravity  of  1.16.  The  bottle  containing  the 
distilled  water  must  be  kept  cool  during  the  whole  operation.” 

Invisible  gaseous  hydrochloric  acid  forms  visible  grayish-white 
fumes  on  coming  into  contact  with  air.  This  is  due  to  combination 
with  the  moisture  of  the  air.  The  intense  greediness  of  hydrochloric 
gas  and  water  for  each  other  is  strikingly  demonstrated  on  opening  a 
test-tube  full  of  the  gas  under  water ; the  latter  rushes  into  and  in- 
stantly fills  the  tube.  If  the  water  is  tinged  with  blue  litmus,  the 
acid  character  of  the  gas  is  prettily  shown  at  the  same  time.  The 
test-tube,  which  should  be  perfectly  dry,  may  be  filled  from  the  de- 
livery-tube direct;  for  the  gas  is  somewhat  heavier  than,  and  there- 
fore readily  displaces,  air.  The  mouth  may  be  closed  by  the  thumb 
of  the  operator. 

Note. — The  process,  as  described  in  the  British  Pharmacopoeia, 
includes  the  use  of  as  much  sulphuric  acid  as  is  theoretically  neces- 
sary for  the  production  of  acid  sulphate  of  sodium  (NaHSO^)  which 
remains  in  the  generating  vessel.  A hot  solution  of'  this  residue 
carefully  neutralized  by  carbonate  of  sodium,  filtered  and  set  aside, 
yields  normal  sulphate  {Sodii  Sulphas,  U.  S.  P.),  in  the  form  of 
transparent  oblique  efflorescent  prisms  (Na^SO^,  IOH2O). 

2NaHS04  + Na^COg  = 2Na2SO,  + H^O  -f  CO^ 

Acid  sulphate  Carbonate  of  Sulphate  of  Water.  Carbonic 
of  sodium.  sodium.  sodium.  acid  gas. 


Chlorine. 

Second  Synthetical  Reaction. — To  some  drops  of  hydro- 
chloric acid  (that  is,  the  common  aqueous  solution  of  the 
gas)  add  a few  grains  of  black  oxide  of  manganese,  and 
warm  the  mixture ; chlorine.,  the  acidulous  radical  of  all 
chlorides,  is  evolvecl,  and  ma}^  be  recognized  by  its  peculiar 
odor,  or  irritating  effect  on  the  nose  and  air-passages. 

4HC1  -f  MnO,  = C\,  -f  + MnCl^ 


240 


SALTS  OP  ACIDULOUS  RADICALS. 


Chlorine-icater. — This  is  the  process  of  the  Pharmacopoeias  for  the 
production  of  chlorine-water  [Liquor  Clilori,  B.  P.,  Aqua  Clilorinii, 
U.  S.  P.),  the  gas  being  first  washed  and  then  passed  into  water. 
Six  fluidounces  of  hydrochloric  acid  diluted  with  two  ounces  of  water, 
and  the  gas  passed  through  a wash-bottle  containing  about  two  ounces 
of  water,  yield  enough  chlorine  to  produce  about  a pint  and  a half  of 
chlorine-water.  On  the  small  scale,  less  than  half  the  acid  is  utilized 
through  incomplete  decomposition  and  incomplete  absorption  of  the 
chlorine  gas.  Chlorine  slowly  decomposes  water  with  production  of 
hydrochloric  acid  and  oxygen  gas ; it  is  best  preserved  in  a green- 
glass  well-stoppered  bottle  in  a cool  and  dark  place.  At  common 
temperatures  (60^  F.),  if  fresh  and  thoroughly  saturated,  chlorine- 
water  contains  more  than  twice  (2.3)  its  bulk  of  chlorine,  or  less  than 
1 per  cent,  (about  0.75)  by  weight 

Note. — To  obtain  the  chlorine  from  other  chlorides,  sulphuric  acid, 
as  well  as  black  oxide  of  manganese,  must  be  added.  Hydrochloric 
acid  is  first  formed.  The  action  described  in  the  above  equation  then 
goes  on,  except  that  half  instead  of  the  whole  of  the  oxygen  of  the 
black  oxide  is  available  for  the  removal  of  the  hydrogen  from  the 
chlorine  of  the  hydrochloric  acid,  the  other  half  being  taken  up  by 
the  hydrogen  of  the  sulphuric  acid.  Thus,  supposing  common  salt 
to  be  the  chloride  used,  the  following  equations  may  represent  the 
supposed  steps  of  the  process  : — 

2NaCl  + H^SO,  = Na.,SO,  + 2HC1, 

MnO,  + H^SO,  = MnSO^  + H.,0  + 0 ; 

then  the  2HC1  +0  = H^O  + Cl^ 

or  the  whole  may  be  included  in  one  equation  : — 

2NaCl  + MnO^  + 2H,SO,  = Na,SO,  + MnSO,  + 2H,0  + Cl^. 

This  reaction  may  have  occasional  analytical  interest,  a very  small 
quantity  of  combined  chlorine  being  recognized  by  its  means.  But 
the  following  test  is  nearly  always  applicable  for  the  detection  of 
this  element,  and  leaves  nothing  to  be  desired  in  point  of  delicacy. 

Analytical  Reaction  ( Test). 

To  a drop  of  h^^drocbloric  acid,  or  to  a dilute  solution  of 
any  other  chloride,  add  solution  of  nitrate  of  silver  ; a 
white  curdy  precipitate  falls.  Pour  off  most  of  the  super- 
natant liquid,  add  nitric  acid  and  boil ; the  precipitate 
does  not  dissolve.  Pour  off  the  acid,  and  add  ammonia; 
the  precipitate  quickly  dissolves.  Neutralize  the  solution 
by  an  acid,  chloride  of  silver  is  once  more  precipitated. 

The  formation  of  this  white  precipitate,  its  appearance,  insolubility 
in  boiling  nitric  acid,  solubility  in  ammonia,  and  reprecipitation  by 
an  acid,  form  abundant  evidence  of  the  presence  of  chlorine.  Its 
occurrence  as  a chloride  of  a metal  is  determined  by  testing  for  the 
metal  with  the  appropriate  reagent ; its  occurrence  as  hydrochloric 
acid  is  considered  to  be  indicated  by  the  odor,  if  strong,  and  the  sour 


BROMIDES. 


241 


taste,  if  weak,  of  the  liquid,  and  the  action  of  the  liquid  on  blue  litmus 
paper,  which,  like  other  acids,  it  reddens.  If  hydrochloric  acid  be 
present  in  excessive  quantity  it  will,  in  addition  to  the  above  reac- 
tions, give  rise  to  strong  effervescence  on  the  addition  of  a carbonate, 
a chloride  being  formed.  The  chlorine  in  insoluble  chlorides,  such 
as  calomel,  ‘‘white  precipitate,”  etc.,  may  be  detected  by  boiling  with 
caustic  potash,  filtering,  acidulating  the  filtrate  by  nitric  acid,  and 
then  adding  the  nitrate  of  silver. 

Antidotes. — In  cases  of  poisoning  by  strong  hydrochloric  acid, 
solution  of  carbonate  of  sodium  (common  washing-soda)  or  a mixture 
of  magnesia  and  water  may  be  administered  as  an  antidote. 


QUESTIONS  AND  EXERCISES. 

414.  A specimen  of  official  Hydrochloric  Acid  contains  31.8  per 
cent,  by  weight  of  gas,  and  its  specific  gravity  is  1.16  ; work  out  a 
sum  showing  what  volume  of  it  will  be  required,  theoretically,  to  mix 
with  black  oxide  of  manganese  for  the  production  of  one  gallon  of 
chlorine-water,  one  fluidounce  of  which  contains  2.66  grains  of  chlo- 
rine. Ans.  fluidounces,  nearly. 

415.  Why  does  hydrochloric  acid  gas  give  visible  fumes  on  coming 
into  contact  with  air  ? 

416.  How  much  chloride  of  sodium  will  be  required  to  furnish  one 
pound  of  chlorine  ? 

417.  Give  the  analytical  reactions  of  chlorides. 

418.  What  antidotes  may  be  administered  in  cases  of  poisoning  by 
hydrochloric  acid  ? 


HYDROBROMIC  ACID  AND  OTHER  BROMIDES. 

Formula  of  Hydrobromic  Acid  HBr.  Molecular  weight  81. 

Bromine.  Source^  Preparation,  and  Properties. — The  acidulous 
radical  of  hydrobromic  acid  and  other  bromides  is  the  element  bro- 
mine, Br  [Bromum,  B.  P.,  Brominium,  U.  S.  P.).  It  occurs  in  nature 
chiefly  as  bromide  of  magnesium  (MgBr2)  in  sea-water  and  certain 
saline  springs.  It  may  be  liberated  from  its  compounds  by  the  pro- 
cess for  chlorine  from  chlorides — that  is,  by  heating  with  black  oxide 
of  manganese  and  sulphuric  acid  (see  previous  page).  It  is  a dark- 
red  volatile  liquid,  emitting  an  odor  more  irritating,  if  possible,  than 
chlorine — of  specific  gravity  2.966,  boiling-point  145.40. 

Quantivalence. — The  atom  of  bromine,  like  that  of  chlorine,  is 
univalent  (Br')  ; its  atomic  weight  is  80.  Free  bromine  has  the 
molecular  formula  Br^,  bromide  of  bromine. 

Hydrobromic  Acid. — The  bromide  of  hydrogen,  hydrobromic  acid, 
is  made  by  decomposing  bromide  of  phosphorus  by  water — PBr.-h 
4H20  = 5HBr+H3P0,. 

Bromide  of  Potassium  (KBr)  is  occasionally  employed  in  phar- 

21 


242 


SALTS  OF  ACIDULOUS  RADICALS. 


macy,  and  is  the  salt,  therefore,  which  may  be  used  in  studying  the 
reactions  of  this  acidulous  radical.  The  official  method  of  making 
the  salt  has  been  alluded  to  under  the  salts  of  potassium  (page  63). 

Other  bromides  are  seldom  used ; they  may  be  prepared  in  the 
same  way  as,  and  closely  resemble,  the  corresponding  chlorides  or 
iodides. 

Bromide  of  Ammonium  (AmBr)  [Ammonii  Bromidum,  B.  P. 
and  U.  S.  P.)  is  prepared  by  agitating  iron  wire  with  a solution  of 
bromine  until  the  odor  of  bromine  can  be  no  longer  perceived,  adding 
solution  of  ammonia,  filtering  and  evaporating  the  filtrate  to  dryness. 
It  forms  a white,  granular  salt  which  becomes  slightly  yellow  on  ex- 
posure to  air,  is  readily  soluble  in  water,  less  so  in  spirit,  and,  when 
heated,  sublimes. 

Solution  of  Bromine,  B.  P.,  10  minims  in  5 ounces,  is  an  aqueous 
solution,  bromine  being  slightly  soluble  in  water. 

Hypohromites,  Bromates,  Ferhromates,  analogous  to  hypochlo- 
rites, chlorates,  and  perchlorates,  are  producible. 

Analytical  Reactions  (Tests). 

First  Analytical  Reaction, — To  a few  drops  of  solution 
of  a bromide  (KBr,  or  NH^Br)  add  solution  of  nitrate  of 
silver ; a yellowish-white  precipitate  of  bromide  of  silver 
(AgBr)  falls.  Treat  the  precipitate  successively  with  nitric 
acid  and  ammonia,  as  described  for  the  chloride  of  silver ; 
it  is  only  sparingly  dissolved  by  the  ammonia. 

Second  Analytical  Reaction, — To  solution  of  a bromide 
add  a drop  or  two  of  chlorine-water,  or  a bubble  or  two  of 
chlorine  gas  ; then  add  a few  drops  of  chloroform  or  ether, 
shake  the  mixture,  and  set  the  test-tube  aside;  the  chlo- 
rine, from  the  greater  strength  of  its  affinities,  liberates  the 
bromine,  which  is  dissolved  by  the  chloroform  or  ether,  the 
solution  falling  to  the  bottom  of  the  tube  in  the  case  of 
the  heavy  chloroform,  or  rising  to  the  top  in  the  case  of  the 
light  ether.  Either  solution  has  a distinct  yellow,  or  red- 
dish-yellow or  red  color,  according  to  the  amount  of  bromine 
present. 

Notes. — This  reaction  serves  for  the  isolation  of  bromine  wheli 
mixed  with  many  other  substances.  Excess  of  chlorine  must  be 
avoided,  as  colorless  chloride  of  bromine  is  then  formed.  Iodides 
give  a somewhat  similar  result ; the  absence  of  iodine  must  therefore^ 
be  insured  by  a process  given  in  the  next  section.  The  above  solu-^ 
tion  in  chloroform  or  ether  may  be  removed  from  the  tube  by  draw- 
ing up  into  pipette  (small  pipe,  a narrow  glass  tube,  usually  having 
a bulb  or  expanded  portion  in  the  centre)  the  bromide  fixed  by  the 
addition  of  a drop  of  solution  of  potash  or  soda,  the  chloroform  or 
ether  evaporated  off,  and  the  residue  tested  as  described  in  the  next 
reaction. 


IODIDES. 


243 


The  above  operation  is  frequently  employed  for  synthetical  pur- 
poses. 

Third  Analytical  Beaction. — Liberate  bromine  from  a 
bromide  by  the  cautious  addition  of  chlorine  or  chlorine- 
water,  then  add  a few  drops  of  cold  decoction  of  starch  ; a 
yellow  combination  of  bromine  and  starch,  commonly 
termed  ‘‘  bromide  of  starch.’^  is  formed. 

Decoction  of  starch  is  made  by  rubbing  down  two  or 
three  grains  of  starch  with  some  drops  of  cold  water,  then 
adding  much  more  water  and  boiling  the  mixture. 

“The  above  reaction  may  he  varied  by  liberating  the  bro- 
mine by  a little  black  oxide  of  manganese  and  a drop  of 
sulphuric  acid,  the  upper  part  of  the  inside  of  the  test-tube 
being  smeared  over  with  some  thick  decoction  of  starch  or 
thin  starch-paste. 

HYDRIODIC  ACID  AND  OTHER  IODIDES. 

Formula  of  Hydriodic  Acid  HI.  Molecular  weight  128. 

Source. — The  acidulous  radical  of  hydriodic  acid  and  other  iodides 
is  the  element  iodine  (I).  It  occurs  in  nature  chiefly  as  iodide  of 
sodium  and  of  magnesium  in  sea- water.  Seaweeds,  sponges,  and  other 
marine  organisms,  which  derive  much  of  their  nourishment  from  sea- 
water, store  up  iodides  in  their  tissues,  and  it  is  from  the  ashes  of 
these  that  supplies  of  iodine  [lodum,  B.  P.,  lodinium,  U.  S.  P.)  are 
obtained. 

Process. — The  seaweed  ash  or  kelp  is  treated  with  water,  insoluble 
matter  thrown"  away,  and  the  decanted  liquid  evaporated  and  set 
aside  to  allow  of  the  deposition  of  most  of  the  sulphates,  carbonates, 
and  chlorides  of  sodium  and  potassium.  The  residual  liquor  is  treated 
with  excess  of  sulphuric  acid,  w^hich  causes  evolution  of  carbonic  and 
sulphurous  or  sulphuretted  gases,  deposition  of  sulphur  and  more 
sulphate  of  sodium,  and  formation  of  hydriodic  acid.  To  the  de- 
canted liquid  is  added  black  oxide  of  manganese,  and  the  mixture  is 
then  slowly  distilled ; the  iodine  sublimes,  and  is  afterwards  purified 
by  re-sublimation. 

2HI  -b  MnO^  + H^SO,  = MnSO,  -f  2}I,0  + I^. 

21ie  analogy  of  chlorine^  bromine,  and  iodine  is  well  indicated 
by  the  fact  that  each  is  obtained  from  its  compounds  by  the  same 
reaction.  Iodine  is  liberated  from  any  iodide  as  bromine  from  bro- 
Vjmides,  or  chlorine  from  chlorides — namely,  by  the  action  of  black 
oxide  of  manganese  and  sulphuric  acid. 

Properties. — Iodine  is  a crystalline  purplish-black  substance ; its 
vapor,  readily  seen  on  heating  a fragment  in  a test-tube,  is  dark 
violet.  Its  vapors  are  irritating  to  the  lungs;  but  a trace  may  be 
inhaled  with  safety  ( Vapor  lodi,  B.  P.).  It  melts  at  239°,  boils  at 
" about  392^,  and  is  entirely  volatilized,  the  first  portions  containing 


214 


SALTS  OF  ACIDULOUS  RADICALS. 


any  cyanide  of  iodine  that  may  be  present.  The  latter  body  occurs 
in  slender  colorless  prisms,  emitting  a pungent  odor. 

Quantivalence  — The  atom  of  iodine,  like  those  of  bromine  and 
chlorine  is  univalent*  (!') ; its  atomic  weight  is  127,  its  molecular 
formula  I2. 

The  Iodide  of  Hydrogen,  or  Hydriodic  Acid,  is  a heavy,  color- 
less gas.  Its  solution  in  water  is  made  by  passing  sulphuretted  hy- 
drogen through  water  in  which  iodine  is  suspended. 

2II2S  + 2I2  = S2  4-  4HI. 

Iodide  of  potassium  (KI)  is  largely  used  in  medicine,  and  hence 
is  the  most  convenient  iodide  on  which  to  experiment  in  studying.the 
reactions  of  this  acidulous  radical.  Solid  iodine  itself  might  l3e  taken 
for  the  purpose ; but  its  use  and  action  in  that*  state  have  already 
been  alluded  to  in  describing  the  iodides  of  potossium,  cadmium,  and 
mercury  ; its  analytical  reactions  in  the  combined  condition  are  those 
which  may  now  occupy  attention. 

Solution  of  Iodine. — Iodine  is  slightly  soluble  in  water  (iodine- 
water),  and  readily  soluble  in  an  aqueous  solution  of  iodide  of  g^as- 
sinm.  Twenty  grains  of  iodine  and  30  of  iodide  of  potassinmT^is- 
solved  in  I ounce  of  distilled  water,  form  Liquor  lodi,  B.  P. ; Liquor 
lodinii  Compositus,  U.  S.  P.,  is  of  the  same  character  and  about  tl^e 
same  strength  ; 32  grains  of  iodine  and  32  of  iodide  of  potassium, 
rubbed  with  I fluidrachm  of  proof  spirit,  and  2 ounces  of  lard  gradu- 
ally mixed  in,  form  Unguentum  lodi,  B.  P.  Unguentum  lodinii 
Compositum,  U.  S.  P.,  and  Unguentum  lodinii,  U.  S.  P.,  are  simi- 
lar preparations.  It  is  more  soluble  in  spirit  ( Tinctura  lodinii,  U. 
S.  P.),  or  in  a spirituous  solution  of  iodide  of  potassium  [Tinctura 
lodi,  B.  P.,  Tinctura  lodinii  Gomposita,  U.  S.  P.).  It  combines 
with  sulphur,  forming  an  unstable  grayish-black  solid  iodide  (S.^I^), 
having  a radiated  crystalline  structure  [Sulph  uris  lodidum,  B.  P. 
and  U.  S.  P.,  and  Unguentum  Sulphuris  lodi di).  If  100  grains  be 
thoroughly  boiled  with  w^ater  the  iodine  will  pass  off'  in  vapor,  and 
about  20  grains  of  sulphur  remain. — B.  P.  and  U.S.P. 

Analytical  Reactions  ( Tests). 

First  Analytical  Reaction. — To  a few  drops  of  an  aque- 
ous solution  of  an  iodide  {e.  g.  KI)  add  solution  of  nitrate 
of  silver ; a yellowish-white  precipitate  of  iodide  of  silver 
(Agl)  falls.  Pour  away  the  supernatant  liquid  and  treat 
the  precipitate  with  nitric  acid,  it  is  not  dissolved;  pour 
aw^ay  the  acid  and  then  add  ammonia,  it  is  only  sparingly 
dissolved. 

* There  is  a compound  of  iodine  having  the  formula  ICI3.  Iodine 
would  therefore  seem  to  be  a trivalent  element  (B")  ; and  bromine  and 
fluorine,  from  their  close  chemical  analogy  with  iodine,  would  necessa- 
rily be  regarded  as  trivalent  also.  From  this  aspect  the  position  of 
chlorine  would  be  anomalous. 


IODIDES. 


245 


This  reaction  is  useful  in  separating  iodine  from  most  other  acidu- 
lous radicals,  but  does  not  distinguish  iodine  from  bromine. 

Ammonia,  it  will  be  remembered,  dissolves  chloride  of  silver  readily ; 
hence  the  presence  of  chloride  of  potassium  in  bromide  or  iodide  may 
be  detected  by  dissolving  in  water,  adding  excess  of  nitrate  of  silver, 
collecting  the  precipitate,  washing,  digesting  in  ammonia,  filtering 
and  adding  excess  of  nitric  acid  to  the  filtrate ; a white  curdy  pre- 
cipitate indicates  a chloride  (of  potassium). 

Second  Analytical  Reaction, — Liberate  iodine  from  an 
iodide  by  the  cautious  addition  of  chlorine,  then  add  cold 
decoction  of  starch  ; a deep-blue  combination  of  iodine  and 
starch,  commonly  termed  “ iodide  of  starch,’’  is  formed. 

Starch  is  highly  sensitive  to  the  action  of  iodine;  this  reaction  is 
consequently  very  delicate  and  characteristic.  Excess  of  chlorine 
must  be  avoided,  or  colorless  chloride  of  iodine  will  be  produced. 
Nitrous  acid,  or  a nitrite  acidulated  wdth  sulphuric  acid,  may  be  used 
iiistea^of  chlorine.  The  reaction  is  not  observed  in  hot  liquids. 

In  testing  bromine  for  iodine  the  bromine  must  be  if^rly  all  re- 
moved by  solution  of  sulphurous  acid  before  the  decoction  of  starch 
is  added. 

Ozone  (O3). — Papers  soaked  in  mucilage  of  starch  containing  iodide 
of  potassium,  form  a test  for  free  chlorine  and  nitrous  acid,  and  are 
also  employed  by  meteorologists  to  detect  an  allotropic  and  energetic 
form  oxygen  termed  by  Schonbein  ozone  (from  o^a;,  ozo^  to  smell). 
Thi^ 'substance  liberates  iodine  from  iodide  of  potassium  (with  forma- 
tion of  iodide  of  starch),  and  is  supposed  to  occur  normally  in  the 
atmosphere,  the  salubrity  or  insalubrity  of  which  is  said  to  be  de- 
pendent to  some  extent  on  the  presence  or  absence  of  ozone.  The 
possible  occurrence  of  nitrous  or  chlorinoid  gases  in  the  air,  however, 
renders  the  test  untrustworthy.  Houzeau  proposes  to  test  for  ozone 
by  exposing  litmus  paper  of  a neutral  tint  soaked  in  a dilute  solution 
of  iodide  of  potassium ; the  potash  set  free  by  action  of  the  ozone 
turns  the  paper  blue.  The  same  paper  without  iodide  would  indicate 
the  extent  to  which  the  effect  might  be  due  to  ammonia  vapor.  Ozone, 
or  rather  ozonized  air,  is  produced  artificially  in  large  quantities  on 
passing  air  through  a box  (Beane’s  Ozone-generator)  highly  charged 
with  electricity.  Small  quantities  may  be  obtained  by  exposing  in 
a loosely  closed  bottle  a stick  of  phosphorus  partially  covered  by 
water.  It  is  a powerful  bleaching,  disinfecting,  and  general  oxidizing 
agent ; insoluble  in  water,  soluble  in  oils  of  turpentine,  cinnamon, 
and  some  other  liquids.  From  experiments  that  have  been  made  by 
Soret  on  the  specific  gravity  of  ozone,  its  molecular  formula  would 
seem  to  be  O3,  that  of  ordinary  oxygen  being  O2,  Its  smell  is  pecu- 
liar.v  (See  p.  211,  also  “Blood.”) 

Third  Analytical  Reaction To  a neutral  aqueous  solu- 

tion of  an  iodide  add  a solution  containing  one  part  of 
sulphate  of  copper  to  two  parts  of  green  sulphate  of  iron  ; 
a dirtv-white  precipitate  of  cuprous  iodide  (Cu^I^)  falls. 

21* 


246 


SALTS  OF  ACIDULOUS  RADICALS. 


2KI  + 2CiiSO,  + 2FeSO,  = CuJ,  + K,SO,  + F^SSO, 

Separation  of  Chlorides,  Bromides,  and  Iodides. — Chlorides  and 
bromides  are  not  affected  in  this  way ; the  reaction  is  useful,  there- 
fore, in  removing  iodine  from  a solution  in  which  chlorides  and 
bromides  have  to  be  sought.  The  total  removal  of  iodine  by  this 
process  is  insured  by  supplementing  the  addition  of  the  cupric  and 
ferrous  sulphate  by  a few  drops  of  ammonia,  any  acid  which  might 
be  keeping  cuprous  iodide  in  solution  being  thereby  neutralized,  ferric 
or  ferrous  hydrate,  precipitated  at  the  same  time,  not  affecting*  the 
reaction.  (Chloride  of  the  rare  metal  palladium  performs  a similar 
useful  office  in  removing  iodinCj  but  not  bromine  or  chlorine,  from 
solutions.  Chlorides  may  be  separated  from  bromides  by  taking 
advantage  of  the  ready  solubility  of  chloride  of  silver,  and  almost 
complete  insolubility  of  bromide  of  silver  in  ammonia. 

Fourth  Analytical  Reaction. — Iodides  have  been  shown 
to  be  useful  in  testing  for  mercuric  salts  (see  the  Mercuiy 
reactions,  p.  112);  a mercuric  salt  (corrosive  sublimate, 
for  example)  may  therefore  be  used  in  testing  for  iodides, 
a scarlet  precipitate  of  mercuric  iodide  (Hgl2)  being  pro- 
duced. 

This  reaction  may  be  employed  where  large  quantities  of  an  iodide 
are  present ; but  its  usefulness  in  analysis  is  much  impaired  by  the 
fact  that  the  precipitate  is  soluble  in  excess  of  the  dissolved  iodide, 
or  in  excess  of  the  mercuric  reagent.  Its  color  and  insolubility  in 
water  distinguish  it  from  mercuric  chloride,  bromide,  and  cyanide, 
which  are  white  soluble  salts. 

Fifth  Analytical  Reaction. — Iodides  have  also  (see  the 
Lead  reactions,  p.  190)  been  shown  to  be  useful  in  testing 
for  lead  salts  ; similarlj^  a lead  salt  (acetate,  for  example) 
maybe  used  in  testing  for  iodides,  a yellow  precipitate  of 
iodide  of  lead  (Pbl2)  soluble  in  hot  water  and  crystallizing 
in  yellow  scales  on  cooling,  being  produced. 

Chloride,  bromide,  and  cyanide  of  lead  are  white;  hence  the  above 
reaction  may  occasionally  be  useful  in  distinguishing  iodine  from  the 
allied  radicals.  But  iodide  of  lead  is  slightly  soluble  in  cold  water; 
hence  small  quantities  of  iodide  cannot  be  detected  by  this  reaction. 
(For  lodates  see  p.  263.) 

Analogies  between  Chlorine,  Bromine,  Iodine,  and  their  Com- 
ponifids. — These  elements  form  a natural  group  or  family,  each  dis- 
tinct from  the  other  yet  closely  related.  Moreover  their  dissimilari- 
ties are  so  curiously  gradational  as  to  irresistibly  suggest  the  idea 
that  some  day  we  may  find  the  differences  between  these  bodies  to 
be  in  degree  rather  than  in  kind.  Thus  chlorine  is  a gas  and  iodine 
a solid,  while  bromine  occupies  the  intermediate  condition.  The 
atomic  weight  of  bromine  is  nearly  midway  between  those  of  chlorine 
and  iodine.  The  same  may  be  said  of  the  weight  of  equal  volumes 


CYANIDES. 


24T 


of  each  in  the  gaseous  state.  The  specific  gravity  of  fluid  chlorine 
is  1.33,  of  iodine  4.95,  while  bromine  is  nearly  3.  Liquid  chlorine  is 
transparent,  iodine  opaque,  bromine  intermediate.  The  crystalline 
forms  of  the  chloride,  bromide,  and  iodide  of  a metal  are  commonly 
identical.  One  volume  of  either  element  in  the  gaseous  state  com- 
bines with  an  equal  volume  of  hydrogen  (at  the  same  temperature)  to 
form  two  volumes  of  a gaseous  acid,  very  soluble  in  water  (hydro- 
chloric acid,  hydrobromic  acid,  hydriodic  acid).  Many  other  analo- 
gies. are  traceable. 


QUESTIONS  AND  EXERCISES. 

419.  State  the  method  by  which  Bromine  is  obtained  from  its 
natural  compounds. 

420.  Mention  the  properties  of  bromine. 

421.  How  may  the  Bromides  of  Potassium  and  Ammonium  be 
made  ? 

422.  By  what  reagents  may  bromides  be  distinguished  from 
chlorides  ? 

423.  Whence  is  iodine  obtained? 

424.  By  what  process  is  iodine  isolated  ? 

425.  State  the  properties  of  iodine. 

426.  What  is  the  nature  of  Iodide  of  Sulphur? 

427.  Give  the  analytical  reactions  of  iodides. 

428.  Which  three  substances  may  be  detected  by  a mixture  of 
iodide  of  potassium  and  mucilage  of  starch  ? 

429.  Describe  a method  by  which  iodides  may  be  removed  from  a 
solution  containing  chlorides  and  bromides. 


HYDROCYANIC  ACID  AND  OTHER  CYANIDES. 

Formula  of  Hydrocyanic  Acid  HNO  or  HCy. 

Molecular  weight  27. 

History  of  Cyanogen. — The  acidulous  radical  of  hydrocyanic  acid 
and  other  cyanides  is  a compound  body,  cyanogen  (Cy).  It  is  so 
named  from  xvavo^  kuanos,  blue,  and  ysvvdco,  gennao,  I generate,  in 
allusion  to  its  prominent  chemical  character  of  forming,  with  iron, 
the  different  varieties  of  Prussian  blue.  It  was  from  Prussian  blue 
that  Scheele,  in  1782,  first  obtained  what  we  now,  from  our  knowl- 
edge of  its  composition,  term  hydrocyanic  acid,  but  which  he  called 
Prussic  acid.  Cyanogen  was  isolated  by  Gay-Lussac  in  1814,  and 
was  the  first  compound  radical  distinctly  proved  to  exist. 

Sources. — Cyanogen  does  not  occur  in  nature,  and  is  only  formed 
from  its  elements  under  certain  circumstances.  It  is  found  in  small 
quantities  among  the  gases  of  iron-furnaces,  and  is  produced  to  a 
slight  extent  in  distilling  coals  for  gas.  In  the  form  of  ferrocyanide 
of  potassium  it  is  obtained  abundantly  by  heating  animal  refuse 


248 


SALTS  OF  ACIDULOUS  RADICALS. 


containing  nitrogen,  such  as  the  scrapings  of  horns,  hoofs,  and  hides 
(5  parts)" with  carbonate  of  potassium  (2  parts)  and  waste  iron 
(filings,  etc.)  in  a covered  iron  pot.  The  residual  mass  is  boiled  with 
water,  the  mixture  filtered,  and  the  filtrate  evaporated  and  set  aside 
for  crystals  to  form.  The  cyanogen,  produced  from  the  carbon  and 
nitrogen  of  the  animal  matter,  unites  with  the  potassium  and  after- 
wards, on  boiling  with  water,  with  iron  to  form  what  is  known  as  the 
yellow  prussiate  of  potash  [Potassoe  Prussias  Flava,  B.  P.),  or  fer- 
rocyanide  of  potassium  (K'4Fe"Cy'g,  [Potassii  Ferrocyanidum,  U. 
S.  P.),  a compound  occurring  in  four-sided  tabular  yellow  crystals. 
It  contains  the  elements  of  cyanogen,  yet  it  is  not  a cyanide,  for  it  is 
not  poisonous,  and  is  otherwise  different  from  cyanides ; it  will  be 
further  noticed  subsequently.  From  this  salt  all  cyanides  are  di- 
rectly or  indirectly  prepared. 

Cyanide  of  'potassium  (KCy)  [Potassii  Cyanidum^  U.  S.  P.), 
wdiich  is  the  most  common,  is  procured  by  fusing  ferrocyanide  of 
potassium  in  a crucible;  carbonic  acid  gas  (OO.J  is  evolved,  iron  (Fe) 
is  set  free,  and  cyanate  of  potassium  (KCyO),  a body  that  will  be 
subsequently  noticed,  is  formed  at  the  same  time ; — 

2K,FeCy6  + 2K,CO,  = lOKCy  + 2KCyO  + Fe2  + 2CO2. 

Double  cyanides  exist,  such  as  the  cyanide  of  sodium  and  silver 
(NaCy.AgCy),  formed  in  the  process  (subsequently  described),  of 
quantitatively  determining  the  amount  of  hydrocyanic  acid  in  a 
liquid  by  a standard  solution  of  nitrate  of  silver : these  compounds 
have,  more  or  less,  the  properties  of  their  constituents.  But  other 
cyanogen  compounds,  not  double  cyanides,  occur  in  which  the  cyano- 
gen is  so  intimately  united  with  a metal  as  to  form  a distinct  radical : 
such  are  ferrocyanides  and  ferridcyanides — salts  which  will  be  noticed 
in  due  course. 

Cyanogen,  like  chlorine,  bromine,  and  iodine,  is  univalent  (Cy'). 
It  may  be  isolated  by  simply  heating  mercuric  cyanide  (HgCy2)  or 
cyanide  of  silver  ( AgCy).  It  is  a colorless  gas,  burning,  when  ignited, 
with  a beautiful  peach-blossom-colored  flame. 

Mercuric  cyanide  is  produced  in  crystals  on  dissolving  1 part  of 
ferrocyanide  of  potassium  in  15  parts  of  boiling  water,  adding  2 parts 
of  mercuric  sulphate,  keeping  the  whole  hot  for  ten  or  fifteen  minutes, 
and  then  filtering  and  setting  aside  to  cool.  In  addition  to  mercuric 
cyanide  (HgCy2),  mercury  (Hg),  ferric  sulphate  (Fe23S04)  and  sul- 
phate of  potassium  (K2SO4),  are  formed.  Any  excess  of  ferrocyanide 
also  gives  Prussian  blue  by  reaction  with  ferric  sulphate.  It  [Hy- 
drargyri  Cyanidum,  U.  S.  P.)  may  also  be  made  by  dissolving  red 
oxide  of  mercury  in  diluted  hydrocyanic  acid.  A small  flame  of 
cyanogen  may  be  obtained  on  heating  a few  crystals  of  mercuric 
cyanide  in  a short  piece  of  glass  tubing  closed  at  one  end,  and  apply- 
ing a light  to  the  other  end  as  soon  as  evolution  of  gas  commences. 


CYANIDES. 


249 


Eeactions. 

Diluted  Hydrocyanic  Acid. 

Synthetical  Reaction. — Dissolve  2 or  3 grains  of  ferrocj^a- 
nide  of  potassium  in  5 or  6 times  its  weight  of  water  in  a 
test-tube,  add  a few  drops  of  sulphuric  acid  and  boil  the 
mixture,  conveying  the  evolved  gas  by  a bent  glass  tube 
(adapted  to  the  test-tube  by  a cork)  into  another  test-tube 
containing  a little  water;  the  product  is  a dilute  solution 
of  h3Tlrocyanic  acid.  Made  by  this  process  in  large  quan- 
tities of  a certain  definite  strength  (2  per  cent.),  this  solu- 
tion is  the  Acidum  HydrocyoMicum  Dilutum.^  B.  P.  and 
U.  S.  P.  A colorless  liquid  of  a peculiar  odor.  Specific 
gravity  0.997.'' 

2K,FeCye  -f  6H,SO,  = FeK^Fe'^Cyg  + 6KHSO,  -f  6HCy. 

The  details  of  the  official  process  are  as  follows : Dissolve  2| 
ounces  of  ferrocyanide  of  potassium  in  10  ounces  of  water,  add  1 
fluidounce  of  sulphuric  acid  previously  diluted  with  four  ounces  of 
water  and  cooled.  Put  the  solution  into  a flask  or  other  suitable 
apparatus  of  glass  or  earthenware,  to  which  are  attached  a condenser 
and  a receiver  arranged  for  distillation  ; and  having  put  8 ounces  of 
distilled  water  into  the  receiver,  and  provided  efficient  means  for 
keeping  the  condenser  and  receiver  cold,  apply  heat  to  the  flask, 
until,  by  slow  distillation,  the  liquid  in  the  receiver  is  increased  to 
17  fluidounces.  Add  to  this  3 ounces  of  distilled  water,  or  as  much 
as  may  be  sufficient  to  bring  the  acid  to  the  required  strength,  so 
that  100  grains  (or  110  minims)  of  itj  precipitated  with  a solution  of 
nitrate  of  silver  {vide  paragraphs  on  quantitative  analysis)  shall 
yield  10  grains  of  dry  cyanide  of  silver. 

The  residue  of  this  reaction  is  acid  sulphate  of  potassium  (KHSO4), 
which  remains  in  solution,  and  ferrocyanide  of  potassium  and  iron 
(Fe"K.^FeCy6),  insoluble  powder  sometimes  termed  Everitt’s  yel- 
low salt,  from  the  name  of  the  chemist  who  first  made  out  the  nature 
of  the  reaction.  The  latter  compound  becomes  bluish-green  during 
the  reaction,  owing  to  absorption  of  oxygen.  Diluted  hydrocyanic 
acid  may  also  be  prepared  by  reaction  of  cyanide  of  silver  and  diluted 
hydrochloric  acid. 

Pure  anhydrous  hydrocyanic  acid  is  a colorless,  highly  volatile, 
intensely  poisonous  liquid,  solidifying  when  cooled  to  a low  tempera- 
ture. It  may  be  made  by  passing  sulphuretted  hydrogen  over  mer- 
curic cyanide.  The  official  solution  of  the  acid  is  fairly  stable,  but 
is  said  to  be  rendered  more  so  by  the  presence  of  a minute  trace  of 
sulphuric  or  hydrochloric  acid. 

Note. — A few  drops  of  diluted  hydrocyanic  acid  so  placed  that 
its  vapor  may  be  inhaled,  forms  the  Vapor  A cidi  Hydrocyaniciy 
B.  P.,  or  Inhalation  of  Hydrocyanic  Acid. 

Hydrocyanic  acid  also  occurs  in  cherry-laurel  water  and  bitter- 
almond  water  [vide  Index). 


250 


SALTS  OP  ACIDULOUS  RADICALS. 


The  methods  of  determining  the  strength  of  solutions  of  hydrocy- 
anic acid  will  be  described  in  connection  with  volumetric  and  gravi- 
metric quantitative  analysis.  They  are  based  on  the  formation  of 
cyanide  of  silver  and  its  solubility  in  solution  of  cyanide  of  potassium, 
as  described  in  the  next  reaction. 

The  hydrocyanic  acid  used  in  pharmacy  is  extremely  liable  to  vari- 
ation in  strength.  It  should  frequently  be  tested  volumetrically. 

Analytical  Reactions  ( Tests), 

First  Analytical  Reaction, — To  a few  drops  of  the  hydro- 
C3’anic  acid  solution  produced  in  the  above  reaction,  or  to 
any  solution  of  a cyanide,  add  excess  of  solution  of  nitrate 
of  silver;  a white  precipitate  of  cyanide  of  silver  (AgCy) 
falls.  When  the  precipitate  lias  subsided,  pour  away  the 
supernatant  liquid,  and  place  half  of  the  residue  in  another 
test-tube : to  one  portion  add  nitric  acid,  and  notice  that 
the  precipitate  does  not  dissolve  ; to  the  other  add  ammo- 
nia, and  observe  that  the  precipitate  is  insoluble  or  only 
sparingly  soluble.  (Chloride  of  silver,  which  is  also  white, 
^ is  readily  soluble  in  ammonia.)  Cj^anide  of  silver  dissolves 
in  solutions  of  cyanides  of  alkali-metals,  soluble  double 
cyanides  being  formed  (c.  ^.,  KCy,  AgCy). 

Solubility  of  precipitates  in  strong  solutions  of  salts. — Cyanide 
of  silver  and  many  other  precipitates  insoluble  in  acids  (similar  re- 
marks apply  to  precipitates  insoluble  in  alkalies)  are  often  soluble 
in  the  strong  saline  liquids  formed  by  the  addition  of  acids  and  alka- 
lies to  one  another.  Hence  the  precaution  of  adding  the  latter  re- 
agents to  separate  portions  of  a precipitate,  or  of  not  adding  the  one 
until  the  other  has  been  poured  away. 

Cyanogen  in  an  insoluble  cyanide,  such  as  cyanide  of  silver 
itself,  is  readily  recognized  on  heating  the  substance  in  a short  piece 
of  glass  tubing  closed  at  one  end  like  a test-tube  and  drawn  out  at 
the  other  end,  so  as  to  have  but  a small  opening ; on  applying  a 
flame,  the  escaping  cyanogen  ignites  and  burns  with  a characteristic 
peach-blossom  tint. 


Antidote. 

Second  Analytical  Reaction. — To  a dilute  solution  of 
hydrocyanic  acid,  or  a soluble  c^^anide,  add  a few  drops  of 
solution  of  a ferrous  salt  and  a drop  or  two  of  solution  of 
a ferric  salt  (ferrous  sulphate  and  ferric  chloride  are  usually 
at  hand) ; to  the  mixture  add  potash  or  soda  (magnesia  or 
carbonate  of  sodium),  and  then  hydrochloric  acid  ; a pre- 
cipitate of  Prussian  blue  remains.  The  decompositions  may 
be  traced  in  the  following  equations: — 


CYANIDES. 


251 


HCy  + KHO  = KCy  + H^O 

2KCy  + FeSO,  = FeCy,  + K,SO, 

4KCy  4-  FeCv^  = K4FeCy(.  or  K,Fcy 

3K,Fcy  + 2Fefi\,  = 12KC1  + Fe^Fcyg. 

The  test  depends  on  the  conversion  of  the  cyanogen  into  ferro- 
cyanogen  by  the  iron  of  a ferrous  salt,  and  the  combination  of  the 
ferrocyanogen,  so  produced,  with  the  iron  of  a ferric  salt. 

Hence  a mixture  of  green  sulphate  of  iron,  solution  of  perchlo- 
ride  of  iron,  and  either  magnesia  or  carbonate  of  sodium,  is  the 
recognized  antidote  in  cases  of  poisoning  by  hydrocyanic  acid  or 
cyanide  of  potassium. 

In  such  an  alkaline  mixture  the  poisonous  cyanide,  by  reaction  with 
ferrous  hydrate,  is  at  once  converted  into  innocuous  ferrocyanide  of 
potassium  or  sodium ; should  the  mixture  become  acid,  the  ferric 
salt  present  reacts  with  the  soluble  ferrocyanide  forming  insoluble 
Prussian  blue,'  which  is  also  inert.  From  the  rapidity  of  the  action 
of  these  poisons,  however,  there  is  seldom  time  to  prepare  an  anti- 
dote. Emetics,  the  stomach-pump,  the  application  of  a stream  of 
cold  water  to  the  spine,  and  the  above  antidote  form  the  usual  treat- 
ment. 

Third  Analytical  Reaction^ — To  solution  of  hydrocyanic 
acid  add  ammonia,  and  common  yellow  sulphydrate  of 
ammonium,  and  evaporate  the  liquid  nearly  or  quite  to 
dryness  in  a small  dish,  occasionally  adding  ammonia  till 
the  excess  of  sulphydrate  of  ammonium  is  decomposed  ; 
acidify  the  liquid  with  hydrochloric  acid,  and  then  add  a 
drop  of  solution  of  a ferric  salt;  a blood-red  solution  of 
sulphocyanide  of  iron  will  be  formed. 

This  is  a very  delicate  reaction.  Some  free’  sulphur  in  the  yellow 
sulphydrate  of  ammonium  unites  with  the  alkaline  cyanide  and  forms 
sulphocyanate  (2AmCy  + S2  = 2AmCyS) ; the  ammonia  combines 
with  excess  of  free  sulphur  and  forms,  among  other  salts,  sulphydrate 
of  ammonium,  the  whole  of  which  is  removed  by  the  ebullition.  If 
the  liquid  has  not  been  evaporated  far  enough,  sulphydrate  of  ammo- 
nium may  still  be  present,  and  give  black  sulphide  of  iron  on  the 
addition  of  the  ferric  salt. 

Hydrocyanic  acid  in  the  blood. — According  to  Buchner  the  blood 
of  animals  poisoned  by  hydrocyanic  acid,  instead  of  coagulating  as 
usual,  remains  liquid  and  of  a clear  cherry-red  color  for  several  days. 
In  one  case  he  obtained  the  reactions  of  the  acid  on  diluting  and  dis- 
tilling the  blood  fifteen  days  after  death,  and  applying  the  usual 
reagents  to  the  distillate.  Aqueous  solution  of  peroxide  of  hydrogen 
(p.  88)  changes  such  blood  to  a deep  brown  color. 

Schonbein's  test  for  hydrocyanic  acid  is  said  to  be  extremely  deli- 
cate. Filtering  paper  is  soaked  in  a solution  of  3 parts  of  guaiacum 
resin  in  100  of  alcohol.  A strip  of  this  paper  is  dipped  in  a solution 
of  1 part  of  sulphate  of  copper  in  50  of  water;  a little  of  the  suspected 


252 


SALTS  OF  ACIDULOUS  RADICALS. 


solution  is  placed  on  tins  paper  and  exposed  to  the  air,  when  it  im- 
mediately turns  blue.  Or  the  paper  may  be  placed  over  the  neck  of 
an  open  bottle  of  medicine  supposed  to^contain  hydrocyanic  acid,  or 
otherwise  exposed  to  the  vapor  of  the  acid. 


QUESTIONS  AND  EXERCISES. 

430.  Write  a paragraph  on  the  history  of  cyanogen. 

431.  Mention  the  source  of  the  cyanogen  of  all  cyanides. 

432.  How  is  Ferrocyanide  of  Potassium  prepared? 

433.  What  is  the  formula  of  ferrocyanide  of  potassium  ? 

434.  Is  ferrocyanide  of  potassium  poisonous  ? 

435.  Write  an  equation  expressive  of  the  reaction  which  ensues 
when  ferrocyanide  and  carbonate  of  potassium  are  brought  together 
at  a high  temperature. 

436.  What  are  the  properties  of  cyanogen  ? How  may  it  be  ob- 
tained in  a pure  condition  ? 

437.  How  is  mercuric  cyanide  prepared  ? 

438.  How  much  real  hydrocyanic  acid  is  contained  in  the  official 
liquid  ? 

439.  Give  details  of  the  preparation  of  hydrocyanic  acid,  and  an 
equation  of  the  reaction. 

440.  State  the  proportion  of  water  that  must  be  added  to  an  aque- 
ous solution  containing  15  per  cent,  of  hydrocyanic  acid  to  reduce 
the  strength  to  2 per  cent. — Ans.  6|  to  1. 

441.  What  are  the  characters  of  pure  hydrocyanic  acid?  How 
may  it  be  obtained  ? 

442.  Enumerate  the  tests  for  cyanogen,  giving  equations. 

443.  Explain  the  action  of  the  best  antidote  in  cases  of  poisoning 
by  hydrocyanic  acid  or  cyanide  of  potassium. 


NITRIC  ACID  AND  OTHER  NITRATES. 

Formula  of  Nitric  Acid  HNO3.  Molecular  weight  63. 

Introduction. — The  group  of  elements  represented  by  the  formula 
NO3  is  that  characteristic  of  nitric  acid  and  all  other  nitrates ; hence 
it  is  expedient  to  regard  these  elements  as  forming  an  acidulous 
radical,  which  may  be  termed  the  nitric  radical.  Like  the  hypo- 
thetical basylous  radical  ammonium  (NH^),  this  supposed  acidulous 
radical  (NO.J  has  not  been  isolated.  Possibly  it  is  liberated  when 
chlorine  is  brought  into  contact  with  nitrate  of  silver ; but  if  so,  its 
decomposition  into  white  crystalline  nitric  anhydride  (N.^05)  and 
oxygen  (0)  is  too  rapid  to  admit  of  its  identification. 

Sources. — The  nitrogen  and  oxygen  of  the  air  combine  and  ulti- 
mately form  nitric  acid  whenever  a current  of  electricity  (as  in  the 
occurrence  of  lightning)  passes.  Nitrates  are  commonly  met  with 
in  waters,  soils,  and  the  juices  of  plants.  In  the  concentrated  plant 
juices  termed  medicinal  “Extracts,”  small  prismatic  crystals  of  ni- 


NITRATES. 


253 


trate  of  potassium  may  occasionally  be  observed.  (The  cubical 
crystals  often  met  with  on  extracts  are  chloride  of  potassium.)  Ni- 
tric acid  and  other  nitrates  are  obtained  from  nitrates  of  potassium 
and  sodium,  and  these  from  the  surface  soil  of  tropical  countries. 
Nitrate  of  potassium  ov  prismatic  nitre  (from  the  form  of  its  crys- 
tals) is  chiefly  produced  in  and  about  the  villages  of  India.  The 
natives  simply  scrape  the  surface  of  waste  grounds,  mud  heaps, 
banks,  and  other  spots  where  a slight  incrustation  indicates  the 
presence  of  appreciable  quantities  of  nitre,  mix  the  scrapings  with 
wood-ashes  (carbonate  of  potassium,  to  decompose  the  nitrate  of 
calcium  always  present),  digest  the  mixture  in  water,  and  evaporate 
the  liquor.  The  impure  product  is  purified  by  careful  recrystalliza- 
tions, and  is  sent  into  commerce  in  the  form  of  white  crystalline 
masses  or  fragments  of  striated  six-sided  prisms.  Besides  its  use  in 
medicine  [Potassii  Nitras,  U.  S.  P.),  it  is  employed  in  very  large 
quantities  in  the  manufacture  of  gunpowder.  Nitrate  of  Sodium 
(Sodii  Nitras,  U.  S.  P.)  occurs  in  more  distinct  incrustations  on 
the  surface  of  the  ground  in  Peru,  Bolivia,  and  Chili,  more  especially 
in  the  district  of  Atacama ; it  is  distinguished  as  Chili  saltpetre  or 
(from  the  form  of  its  crystals — obtuse  rhomboids)  cubic  nitre,  and  is 
chiefly  used  as  a manure  and  as  a source  of  nitric  acid,  its  tendency 
to  absorb  moisture  unfitting  it  for  use  in  gunpowder.  In  many  parts 
of  Europe  nitrate  of  potassium  is  made  artificially  by  exposing  heaps 
of  animal  manure,  refuse,  ashes,  and  soil  to  the  action  of  the  air  and 
the  heat  of  the  sun : in  the  course  of  a year  or  two  the  nitrogen  of 
the  animal  matter  becomes  oxidized  to  nitrates,  and  the  latter  are 
removed  by  washing. 

Note. — The  word  nitric  is  from  nitre,  the  English  equivalent  of 
the  Greek  vCifpov  (nitron),  a name  applied  to  certain  natural  deposits 
of  natron  (carbonate  of  sodium),  for  which  nitrate  of  potassium 
seems  at  first  to  have  been  mistaken.  Saltpetre  is  simply  sal  petrce, 
salt  of  the  rock,  in  allusion  to  the  natural  origin  of  nitrate  of  potas- 
sium. Sal  'prunella  (from  sal,  a salt,  and  pruna,  a live  coal)  is  ni- 
trate of  potassium  melted  over  a fire  and  cast  into  cakes  or  bullets. 

The  nitric  radical  is  univalent  (NO3'). 

Constitution  of  Salts. 

It  is  here  necessary  again  to  caution  the  reader  against  regarding 
salts  as  invariably  possessing  a known  constitution,  or  supposing  that 
they  always  possess  two  or  more  sides,  or  contain  definite  radicals. 
The  erroneous  conception  which,  of  all  others,  is  most  likely  to  be 
imperceptibly  formed  is  that  of  considering  salts  binary  bodies.  For, 
first  the  names  of  salts  are  necessarily  binary.  A student  hears  the 
names  “ sulphate  of  iron,”  “ sulphate  of  copper,”  and  simultaneously 
receives  the  impression  that  each  salt  has  two  sides,  copper  or  iron 
occupying  one  and  something  indicated  by  the  w^ords  “ sulphate  of” 
the  other.  Such  words  “ vitriol,”  green  or  blue,  or  “ nitre,”  would 
perhaps  implant  unitary  ideas  in  the  mind ; but  it  is  simply  impossi- 
ble to  give  such  names  to  all  salts  as  will  convey  the  impression  that 
each  salt  is  a whole,  and  therefore  unitary.  The  name  “ sulphate  of 
potash”  produces  binary  impressions ; and  the  less  incorrect  name, 
22 


254 


SALTS  OP  ACIDULOUS  RADICALS. 


“ sulphate  of  potassium,”  is  in  this  respect  no  better.  Secondly,  it 
is  impracticable  to  study  salts  as  a whole.  Teachers  are  unanimous 
in  the  opinion  that  students  should  first  master  the  reactions  charac- 
teristic of  the  metals  in  salts,  and  then  the  residues  which,  with 
those  metals,  make  up  the  salts,  or  vice  versa.  It  is  not  only  im- 
practicable, but  impossible,  to  study  salts  as  a whole ; binary  ideas 
concerning  them  are  therefore  almost  inevitably  imbibed.  We  come 
to  regard  a salt  as  a body  which  splits  up  in  one  direction  only,  look 
upon  nitre,  for  instance,  and  all  other  nitrates,  as  containing  N 0.^  and 
a metal,  K ; whereas  KNO3  maybe  split  up  into  KNO2  and  0;  or 
into  K^O,  N2’  ^5  5 contain  K2O  and  N2O5.  These  are 

the  chief  disadvantages  attending  the  employment  of  the  binary 
hypothesis  in  studying  chemical  compounds : if  they  be  borne  in 
mind,  the  hypothesis  may  be  freely  used  without  much  danger  of 
permanent  mental  bias.  Thus  in  nitre  let  the  group  of  elements  (NO3) 
which,  with  potassium,  makes  up  the  whole  salt  be  called  the  nitric 
radical,  the  name  of  the  latter  being  directly  derived  from  its  hydro- 
gen salt.  Similarly  allow  the  acidulous  residues  of  other  salts  of 
metals  to  be  termed  respectively  the  chloric,  acetic,  sulphurous,  sul- 
phuric, carbonic,  oxalic,  tartaric,  phosphoric,  citric,  boracic  radicals. 
In  short,  these  compound  radicals  should  be  regarded  as  groupings 
common  to  many  salts,  and  which  may  usually  be  transferred  without 
any  apparent  breaking  or  splitting ; at  the  same  time  we  must  be 
prepared  to  find  that  occasionally  a salt  divides  in  other  directions. 
In  this  way  perhaps  erroneous  impressions  will  gain  least  hold  on  the 
mind,  and  a way  be  left  open  for  the  easy  entrance  of  new  truths, 
should  the  real  constitution  of  salts  be  discovered. 

Formerly  salts  (such  as  sulphate  of  magnesium)  were  regarded  as 
containing  (a)  an  oxide  of  a metal  (MgO)  and  an  anhydride  (SO3), 
the  latter  being  incorrectly  called  an  acid  (sulphuric  acid),  or  (5)  as 
containing  two  simple  radicals  [e.  g.  KI,  NaCl,  KCy,  HgS) — the 
former  being  called  oxyacid  salts,  or  oxysalts,  and  the  latter  haloid 
salts  (from  als,  seasalt,  and  eidos,  likeness).  Such  distinc- 
tion is  no  longer  maintained,  the  two  classes  being  merged.  This  is 
an  important  educational  gain  on  the  side  of  simplicity  ; for,  whereas 
under  the  old  system  much  time  was  necessarily  expended  before 
salts  of  a metal  and  salts  of  the  oxide  of  that  metal  could  be  distin- 
guished (e.  g.  KI  and  Mg0,S03),  now,  all  salts  being  regarded  as 
salts  of  the  metals  themselves  (e.  g.  KI  and  MgS04), 
tinction  is  necessary. 


Reactions. 

Nitric  Acid. 

Synthetical  Reaction, — To  a fragment  of  nitrate  of  potas- 
sium or  nitrate  of  sodium  in  a test-tube  add  a drop  or  two 
of  sulphuric  acid,  and  warm  ; nitric  acid  (UNO,)  is  evolved 
in  vapor.  The  fumes  may  be  condensed  by  a bent  tube 
fitted  to  the  test-tube,  not  by  a cork  as  for  hydrochloric 
acid,  because  the  nitric  vapors  w^ould  strongly  act  on  it, 


NITRATES. 


255 


blit  by  plaster  of  Paris,  a paste  of  which  sets  hard  on  being 
set  aside  for  a short  time,  and  is  unaffected  by  the  acid. 

On  a somewhat  larger  scale  nitric  acid  may  be  prepared 
by  heating,  in  a stoppered  or  plain  retort,  a mixture  of 
equal  weights  of  nitrate  of  potassium  and  sulphuric  acid  ; 
the  acid  distils  over,  and  acid  sulphate  of  potassium  re- 
mains behind : — 

KNO3  + H,SO,  = HNO3  + KHSO, 

Nitrate  of  Sulphuric  Nitric  Acid  sulphate 

potassium.  acid.  acid.  of  potassium. 

Half  the  quantity  of  sulphuric  acid  may  be  taken  ; but  in  that  case 
neutral  sulphate  of  potassium- (K2SO4)  is  produced,  which,  from  its 
hard,  slightly  soluble  character,  is  removed  with  difficulty  from  the 
retort.  On  the  manufacturing  scale  the  less  proportion  is  used  ; but 
instead  of  retorts  iron  cylinders  are  employed,  from  which  the  residual 
salt  is  removed  by  chisels.  Moreover  the  cheaper  sodium  salt  is  the 
nitrate,  from  which  manufacturers  usually  prepare  nitric  acid,  seven 
parts  of  nitrate  of  sodium  and  four  of  sulphuric  being  employed. 

Note. — The  acid  sulphate  of  potassium  is  readily  converted  into 
neutral  sulphate  [Potassii  Sulphas,  U.  S.  P.)  by  dissolving  in  water, 
adding  carbonate  of  potassium  until  effervescence  ceases  to  occur, 
filtering,  and  setting  aside  to  crystallize. 

Pure  nitric  acid  (HNO^)  is  a colorless  liquid,  somewhat  difficult 
of  preparation ; its  specific  gravity  is  1.52.  The  strongest  acid  met 
with  in  commerce  has  a sp.  gr.  of  1.5,  and  contains  93  per  cent,  of 
real  nitric  acid  (HNO3);  it  fumes  disagreeably,  is  unstable,  and, 
except  as  an  escharotic,  is  seldom  used.  The  British  and  United 
States  Pharmacopoeias  contain  two  acids  : Acidum  Nitricum,  pre- 
pared as  above,  of  sp.  gr.  1.42  (also  in  U.  S.  P.),  and  containing  70 
per  cent,  of  real  acid  HINO3);  and  another,  Acidum  Nitricum 
Dilutum,  sp.  gr.  1.101  (tJ.  S.  P.  1.068),  containing  nearly  17^  (17.44) 
per  cent.  Either  of  the  stronger  liquids,  although  containing  Avater, 
is  usually  simply  termed  “ nitric  acid.”  The  official  nitric  acid,  of 
sp.  gr.  1.42,  is  a definite  hydrous  acid  (2HNO3,  3H2O) ; it  distils  at 
250^  F.  without  change.  If  a weaker  acid  be  heated  it  loses  water,  if 
a stronger  acid  be  heated  it  loses  nitric  acid,  until  the  density  of  1.42 
is  reached.  Aqua  fortis  is  an  old  name  for  nitric  acid  [Aquafortis 
simplex,  sp.  gr.  1.22  to  1.25;  Aqua  fortis  duplex,  1.36).  The 
strength  of  a specimen  of  nitric  acid  is  determined  by  volumetric 
analysis.  Nitric  anhydride  (N^Og),  sometimes  but  erroneously 
called  anhydrous  nitric  acid,  is  a solid  crystalline  substance  formed 
on  passing  dry  chlorine  over  dry  nitrate  of  silver. 

Aqua  Regia. — Three  fluidounces  of  nitric  acid  (B.  P.),  four  of 
hydrochloric  acid  (B.  P.),  (3  to  5 by  weight  forms  the  Acidum 
Nitromuriaticum,  U.  S.  P.),  and  twenty-five  of  water,  give  the 
Acidum  Nitrohydrochloricum  Dilutum  of  the  British  Pharmaco- 
poeia. The  acids  are  ordered  to  be  mixed  twenty-four  hours  before 
dilution  to  insure  mutual  decomposition  and  full  development  of  the 
chief  active  product,  chlorine  : — 


256 


SALTS  OF  ACIDULOUS  RADICALS. 


2HNO,  -h  6HC1  = N2O2CI,  + 4H2O  + CI2 

Nitric  acid.  Hydrochloric  Chlorouitric  Water.  Chlorine, 

acid.  gas. 

In  the  later  stages  of  the  reaction,  the  decomposition  expressed  in 
the  following  equation  also  probably  occurs : — 

HNO3  + 3HC1  = NOCl  + 2H2O  + Cl, 

Nitric  acid.  Hydrochloric  Chloronitrous  Water.  Chlorine, 
acid.  gas. 

The  same  reaction  occurs  if  the  acids  are  mixed  after  dilution,  but 
is  not  complete  for  a week  or  a fortnight  (Tilden).  The  undiluted 
mixture  of  acids  is  known  as  aqua  regia,  so  called  from  its  property 
of  dissolving  gold,  “ the  king’’  of  metals. 

Analytical  Reactions  ( Tests), 

First  Analytical  Reaction, — To  a solution  of  any  nitrate 
(e.  g,  KNO3)  add  sulphuric  acid,  and  then  copper  turnings, 
and  warm;  colorless  nitric  oxide  gas  (NO)  is  evolved, 
which  at  once  unites  with  the  oxygen  in  tlie  tube,  giving 
red  fumes  of  nitric  peroxide  or  peroxide  of  nitrogen 
(NO,). 

2KNO3  + 5ILSO,+  Cti3=  2NO  + 3CuS0,4-4H,0  + 2KHSO, ; 

2NO+  0,=  2N0,. 

Performed  on  a larger  scale,  in  a vessel  to  which  a delivery-tube 
is  attached,  this  reaction  becomes  of  synthetical  interest,  being  the 
process  for  the  preparation  of  nitric  oxide  gas  for  the  purposes  of 
chemical  experiment. 

Small  amounts  of  a nitrate  may  be  overlooked  by  this  test,  tlie 
color  of  the  red  fumes  not  being  very  intense. 

Undiluted  nitric  acid  poured  on  to  copper  turnings  gives  dense  red 
vapors  of  nitrous  acid  (HNO,),  nitrous  anhydride  (N,03),  and 
nitric  peroxide  (NO,). 

Second  Arialytical  Reaction, — To  a cold  solution  of  the 
nitrate,  even  if  very  dilute,  add  three  or  four  crystals  of 
sulphate  of  iron,  shake  gently  for  a minute  in  order  that 
some  of  the  sulpliate  may  become  dissolved,  and  then  pour 
eight  or  ten  drops  of  strong  sulphuric  acid  down  the  side 
of  the  test-tube,  so  that  it  may  form  a layer  at  the  bottom 
of  the  vessel ; a reddish-purple  or  black  coloration  will 
appear  betw^een  the  acid  and  the  supernatant  liquid. 

This  is  a very  delicate  test  for  the  presence  of  nitrates.  I'he  black 
color  is  due  to  a solution  or,  perhaps,  combination  of  nitric  oxide 
with  a portion  of  the  ferrous  salt.  The  nitric  oxide  is  liberated  from 
the  nitrate  by  the  reducing  action  of  the  hydrogen  of  the  sulphuric 
acid,  the  sulphuric  radical  of  which  is  absorbed  by  the  ferrous  sul- 
phate, the  latter  salt  becoming  ferric  sulphate. 

2nN03+  31T.,SO,+  6FeSO,  = 4H.,0  + 3(Fe.,3SOJ  + 2NO. 


NITRATES. 


257 


The  process  of  oxidation  is  one  frequently  employed  in  experi- 
mental chemistry ; and  nitrates,  from  their  richness  in  oxygen,  but 
more  especially  because  always  at  hand,  are  the  oxidizers  usually 
selected  for  the  purpose.  In  the  operation  they  generally  split  up  in 
one  way,  namely,  into  oxide  of  their  basylous  radical,  nitric  oxide 
gas,  and  available  oxygen.  Thus  hydrogen  nitrate  (nitric  acid)  yields 
oxide  of  hydrogen  (water)  and  the  other  bodies  mentioned,  as  shown 
in  the  following  equation  : — 


4NHO3  = 2H2O  + 4NO  + 30.,. 


When  nitrates,  other  than  nitric  acid,  are  used  for  the  purpose  of 
oxidation,  a stronger  acid,  generally  sulphuric,  is  commonly  added  in 
order  that  nitric  acid  may  be  formed ; the  hydrogen  nitrate  splitting 
up  more  readily  than  other  nitrates. 

Nitrate  of  ammonium  [Ammonii  Nitras,  U.  S.  P.)  is  readily 
formed  on  neutralizing  nitric  acid  with  carbonate  of  ammonium.  It 
occurs  in  long  prismatic  crystals  or  in  fused  masses,  soluble  in  about 
half  its  weight  of  water  at-  70^  and  in  twice  its  weight  of  alcohol, 
and  when  heated,  yields  nitrous  oxide,  or  laughing-gas  (N2O). 


NH.NOg  = N2O  + 2H2O. 


Nitrous  oxide  is  thus  prepared  for  use  as  an  anaesthetic.  When 
required  for  inhalation,  it  should  be  washed  from  any  possible  trace 
of  acid  or  nitric  oxide,  by  being  passed  through  solution  of  potash, 
and  through  solution  of  ferrous  sulphate. 

Nitrous  oxide  is  slightly  soluble  in  warm  water,  more  so  in  cold. 
By  pressure  it  may  be  liquefied  to  a colorless  fluid,  and  by  simulta- 
neous cooling  solidified.  It  supports  combustion  almost  as  well  as 
oxygen. 

The  five  oxides  of  nitrogenfh^wOi  now  been  mentioned,  namely  — 


Nitrous  oxide N2O 

Nitric  oxide* NO 

Nitrous  anhydride  . . N^O^  or 
Nitric  peroxide*  . . . NO2 
Nitric  anhydride  . . . N2O5  ^ 


Nitrous  oxide  is  a colorless  gas  not  altered  by  exposure  to  air; 
nitric  oxide  is  also  colorless,  but  gives  red  fumes  in  the  air ; nitrous 
anhydride  is  a red  vapor  condensible  to  a blue  liquid;  nitric  peroxide 
is  a red  vapor  condensible  to  an  orange  liquid  ; nitric  anhydride 
is  a^  colorless  crystalline  solid.  The  two  anhydrides  by  absorbing 
water  yield  respectively  nitrous  acid  (HNO2)  and  nitric  acid  (HNO3). 
This  series  of  compounds  forms  a good  illustration  of  the  doctrine 
of  multiple  proportions  (p.  42). 

Third  Analytical  Reaction, — Direct  the  blov^pipe-flame 
on  to  charcoal  until  a spot  is  red-hot ; now  place  on  the 
spot  a fragment  of  nitrate  ; deflagration  ensues. 

* The  specific  gravities  of  these  gases  indfcate  that  NO  and  NO,  are 
the  correct  formuloe,  and  not  N2O2  and  N 0^. 

22* 


258 


SALTS  OF  ACIDULOUS  RADICALS. 


This  reaction  does  not  distinguish  nitrates  from  chlorates.  It  is 
insufficient  for  the  recognition  of  very  small  quantities  of  either  class 
of  salts,  especially  when  they  are  mixed  with  other  substances. 

Gunpoivder  is  an  intimate  mechanical  mixture  of  75  parts  of  nitre, 
15  to  12  J parts  of  charcoal,  and  10  to  12^  parts  of  sulphur.  In 
burning  it  may  be  said  to  give  sulphide  of  potassium  (the  white  smoke, 
K2S),  nitrogen  (N),  carbonic  oxide  (CO),  and  carbonic  acid  (CO2) 
gases,  though  the  decomposition  is  seldom  complete.  The  sudden 
production  of  a large  quantity  of  heated  gas  from  a small  quantity 
of  a cold  solid  is  sufficient  to  account  for  all  the  effects  of  gunpowder. 

Fourth  Analytical  Reaction. — To  nitric  acid  or  other 
nitrate  add  solution  of  “ sulphate"  of  indigo  the  color  is 
discharged. 

Solution  of  Sulphate  of  Indigo f B.  P.  (Sulphindylic  or  Sul- 
phindigotic  acid),  is  made  by  digesting  5 grains  of  dry  finely  pow- 
dered indigo  in  a small  quantity  of  strong  sulphuric  acid  in  a test- 
tube  for  an  hour,  the  mixture  being  kept  hot  by  a water-bath ; the 
blue  liquid  is  then  poured  into  10  ounces  of  sulphuric  acid,  the  whole 
well  shaken,  set  aside,  and  the  clear  liquid  decanted.  Free  chlorine 
also  destroys  the  color  of  this  reagent. 

Indigo  B.  P.  (CgH^NO)  is  a blue  coloring-matter  deposited  wdien 
infusion  of  various  species  of  Indigofera  is  exposed  to  air  and  slight 
warmth.  Under  these  circumstances,  indican^  a yellow  transparent 
amorphous  substance,  soluble  in  'water,  breaks  up  into  indigo,  which 
is  insoluble  and  falls  as  a sediment,  and  a sort  of  sugar  termed  indi- 
glucin.  The  indigo  is  collected,  drained,  pressed,  and  dried.  By 
action  of  deoxidizing  agents  indigo  is  converted  into  soluble  colorless 
indigogen,  reduced  indigo,  or  white  indigo ; 1 part  of  powdered 
indigo,  2 of  green  sulphate  of  iron,  3 of  slaked  lime,  and  200  of 
water,  shaken  together  and  set  aside  in  a well-closed  bottle,  gives 
this  colorless  indigo.  A piece  of  yarn,  calico,  or  similar  fabric,  dipped 
into  such  a solution,  and  exposed  to  air,  becomes  dyed  blue,  depo- 
sition of  insoluble  indigo-blue  occurring  within  the  cells  and  vessels 
of  the  fibre.  This  operation  is  readily  performed  on  the  small  scale, 
and  forms  a good  illustration  of  the  characteristic  feature  of  the  art 
of  dyeing,  namely,  the  introduction  of  soluble  coloring-matter  into  a 
fabric  by  permeation  of  the  walls  of  its  cellular  and  vascular  tissue, 
and  the  imprisonment  of  that  coloring-matter  by  conversion  into  a 
solid  and  insoluble  form  [vide  also  p.  117). 

Pure  indigo,  or  indigotin,  may  be  obtained  in  beautiful  needles 
by  spreading  a paste  of  indigo  and  plaster  of  paris  on  a tin  plate, 
and  when  dry  placing  a lamp  underneath,  moving  the  latter  from 
place  to  place  as  the  indigo  sublimes  and  condenses  on  the  surface  of 
the  plaster.  It  may  also  be  obtained  in  crystals  by  gently  boiling 
finely  powdered  indigo  with  aniline,  filtering  while  hot,  and  setting 
aside ; these  crystals  may  be  washed  with  alcohol.  Hot  paraffin  may 
be  employed  instead  of  aniline.  It  is  possible  to  obtain  indigotin 
artificially. 

Distinction  hetween  nitric  acid  and  other  nitrates. — Presence  of 
the  qitric  radical  in  a solution  having  been  proved  by  the  above  reac- 


CHLORATES. 


259 


tions,  its  occurrence  as  the  nitrate  of  a metal  is  demonstrated  by  the 
neutral,  or  nearly  neutral,  deportment  of  the  liquid  with  test-paper 
and  the  detection  of  the  metal — its  occurrence  as  nitric  acid  by  the 
sourness  of  the  liquid  to  the  taste  and  the  effervescence  produced  on 
the  addition  of  a carbonate. 

Antidote, — In  cases  of  poisoning  by  strong  nitric  acid,  solution  of 
carbonate  of  sodium  (common  washing-soda)  or  a mixture  of  magnesia 
and  water  may  be  administered  as  antidotes. 


QUESTIONS  AND  EXERCISES. 

444.  Trace  the  origin  of  nitrates. 

445.  In  what  does  cubic  nitre  differ,  chemically,  from  prismatic 
nitre  ? 

446.  Describe  a process  by  which  nitrate  of  potassium  may  be  ob- 
tained artificially. 

447.  State  the  difference  between  nitrate  of  potassium,  nitre,  salt- 
petre, and  sal  prunella. 

448.  What  group  of  elements  is  characteristic  of  all  nitrates  ? and 
what  claim  has  this  group  to  the  title  of  radical  ? 

449.  Mention  the  usual  theory  regarding  the  manner  in  which 
atoms  are  arranged  in  reference  to  each  other  in  such  salts  as  nitrate 
of  potassium. 

450.  How  is  Nitric  Acid  prepared  ? 

45  L.  Give  the  properties  of  nitric  acid. 

452.  What  reactions  occur  when  strong  nitric  and  hydrochloric 
acids  are  mixed? 

453.  How  is  nitric  oxide  prepared  ? 

454.  Enumerate  and  explain  the  tests  for  nitrates. 

455.  Into  what  substances  does  nitric  acid  usually  split  when  em- 
ployed as  an  oxidizing  agent? 

456.  How  is  nitrous  oxide  prepared  ? 

457.  Enumerate  the  five  oxides  of  nitrogen. 

458.  What  is  the  nature  of  gunpowder  ? 

459.  Write  a few  sentences  on  the  chemistry  of  indigo,  one  of  the 
tests  for  nitric  acid. 

460.  How  is  nitric  acid  distinguished  from  other  nitrates? 

461.  What  quantity  of  cubic  nitre  will  be  required  to  produce  ten 
carboys  of  official  nitric  acid,  each  containing  114  pounds? — Ans. 
1076|  pounds. 


CHLORIC  ACID  AND  OTHER  CHLORATES. 

Formula  of  Chloric  Acid  HCIO3.  Molecular  weight  84.5. 

Hypochlorous  Acid  (HCIO),  and  other  Hypochlorites. 

Place  a few  grains  of  red  oxide  of  mercury  in  a test-tube, 
half-fill  the  tube  with  chlorine- water  and  well  shake  the  mix- 


260 


SALTS  OF  ACIDULOUS  RADICALS. 


ture ; the  resulting  liquid  is  a solution  of  hypochlorous 
acid,  mercuric  oxychloride  remaining  undissolved : — 

2HgO  + 201,  + up  = 2IIC10  + Hg.,OCl,. 

By  tlie  double  decomposition  of  hypochlorous  aoid  and 
oxides  or  hj^drates,  other  pure  hydrochlorites  are  formed  : — 
HCIO  + NaHO  = NaClO  -f  H^O. 

The  direct  action  of  chlorine  on  metallic  hydrates  is  sup- 
loosed  to  give  a mixture  of  chloride  and  hypochlorite,  as 
described  in  connection  with  the  S3mthetical  reactions  of 
Sodium  (p.  Y2,  Liquor  Sodm  Chloratae^  B.  P.)  and  Calcium 
(p.  96,  Calx  chlorata^  B.  P.). 

Cl,  + 2NaHO  = NaCl,NaC10  + 11,0; 

2C1,  + 2CaH.p,  = CaCl,,Ca2C10  + 2H,0. 

But  the  presence  of  chlorides  cannot  be  directly  demon- 
strated in  these  bodies  ; so  that  their  constitution  is  not 
definitely  determined.  The  action  of  acids  on  them  results 
in  the  evolution  of  chlorine;  hence  the  great  value  of  the 
calcium  compound  (chlorinated  lime,  or  cldoride  of  lime) 
in  bleaching  operations: — 

CaCl„  Ca2C10  + 2H^SO,  = 2C1,  -f  2CaSO,  + 2H,0. 
The  solubility  of  hypochlorites  in  water,  their  peculiar 
odor,  greatly  intensified  on  the  addition  of  acid,  and  their 
bleaching-powers  (see  the  above  calcium  reaction)  are  the 
characters  on  which  to  rely  in  searching  for  hypochlorites. 

Chlorates. 

The  group  of  elementary  atoms  represented  by  the  formula  CIO3 
is  that  characteristic  of  chloric  acid  and  all  other  chlorates ; hence 
it  is  expedient  to  regard  it  as  being  an  acidulous  radical,  which  may 
be  termed  the  chloric  radical.  Like  the  nitric  radical,  it  has  not 
been  isolated.  Chloric  anhydride  also  (CI2O5)  unlike  nitric  anhy- 
dride, has  not  yet  been  obtained  in  the  free  condition. 

Chlorates  are  artificial  salts.  They  are  formed  by  simply  boiling 
aqueous  solutions  of  the  common  bleaching  salts  (chlorinated  lime, 
chlorinated  soda,  chlorinated  potash).  Heat  thus  converts 

5 NaCl 

Chloride  of 
sodium. 

5KC1 

Chloride  of 
potassium. 

5CaCl 

Chloride  of 
calcium. 


3(NaCl,  NaClO)  ] ^ 

Chlorinated  Soda.  r into 

3(KC1,  KCIO)  ] 

Chlorinated  illto 

potash.  I 

3(CaCl2,  Ca2C10)  ] 

Chlorinated  ^ into 

lime.  I 


NaClOg 

Chlorate  of 
sodium. 

KCIO3 

Chlorate 
of  potassium. 

Ca2C103 

Chlorate  of 
calcium. 


and 


and 


I and  I 


CHLORATES. 


261 


One  chlorate  may  also  be  made  from  another  by  double  decomposi- 
tion. In  making  chlorates  economically  the  chlorinated  salt  is  spe- 
cially prepared  for,  and  in  the  same  vessel  as,  the  chlorate. 

Chlorate  of  Potassium. 

Thus  Chlorate  of  Potassium  {Potassii  Chloras^  U.  S.  P.) 
is  commercially  made  by  saturating  with  chlorine  gas  a 
moistened  mixture  of  three  parts  of  chloride  of  potassium 
and  ten  of  slaked  lime,  and  well  boiling  the  product.  Chlo- 
rinated lime  is  first  formed  ; this,  on  boiling  with  water, 
splits  up  into  chloride  of  calcium  and  chlorate  of  calcium, 
and  the  latter  reacting  on  the  chloride  of  potassium  yields 
chloride  of  calcium  and  chlorate  of  potassium. 

6(Ca2HO)  4-  6C1,  = 3(CaCl„Ca2C10)  -f 
3(CaCl2,Ca2C10)  = Ca2C103  + bCaCl^; 

Ca2C103  + 2KC1  = CaCl,  + 2KCIO3. 

The  operation  may  be  conducted  on  a small  scale  by  rub- 
bing together  in  a mortar  the  above  proportions  of  ingre- 
dients in  ounces  or  half-ounces,  adding  enough  water  to 
make  the  whole  assume  the  character  of  damp  lumps, 
placing  the  porous  mass  in  a funnel  (loosely  plugged  with 
stones  or  pieces  of  glass)  and  passing  chlorine  gas  (p.  24) 
up  through  the  neck  of  the  funnel.  When  the  whole  mass 
has  become  of  a slight  pink  tint  (due  to  a trace  of  perman- 
ganate) it  should  be  turned  into  a dish,  well  boiled  with 
water,  filtered,  the  filtrate  evaporated  if  necessary,  and  set 
aside;  the  chlorate  of  potassium  crystallizes  out  in  color- 
less rhomboidal  plates,  chloride  of  calcium  remaining  in 
the  mother-liquor. 

In  the  official  process,  carbonate  of  potassium  instead  of  chloride 
is  used ; but  otherwise  it  is  similar  to  the  method  just  described. 
Chlorinated  potash  and  chlorinated  lime  are  first  formed — 

K2CO3  -f  Ca2HO  + Cl,  = KCl,  KCIO  + CaCO.^  + H,0, 
6(Ca2HO)  -f  6C1,  = 3(CaCl2,Ca2C10)  -f  6H,0; 

these,  on  boiling  with  water,  split  up  into  chlorates  and  chlorides — 

3(KC1,  KCIO)  = KCIO3  -i-  5KC1 
3(CaCl2,  Ca2C10)  = Ca2C103  + 5CaCl„ 

the  whole  of  the  chloride  of  potassium  and  chlorate  of  calcium 
finally  yielding  chlorate  of  potassium  and  chloride  of  calcium, 

2KC1  -h  Ca2C103  = CaCl,  -f  2KCIO3. 

Neglecting  intermediate  decomposition,  the  reactions  may  be  repre- 
sented by  the  following  equation ; — 


262 


SALTS  OF  ACIDULOUS  RADICALS. 


6CI2  K,C03  H-  6CaH,02  = 2KOIO3  4-  CaCOg  4- 

Clilorine.  Carbouate  of  Hydrate  of  Chlorate  of  Carbonate  of 

potassium.  calcium.  potassium.  calcium. 

5CaCl2  4-  6H,0. 

Chloride  of  Water, 

calcium. 

Chlorate  of  potassium  is  soluble  in  water  to  the  extent  of  6 or  7 
parts  in  100  at  common  temperatures.  It  is  usually  administered 
medicinally  in  aqueous  solution,  sometimes  also  in  lozenges  [Tro- 
cMsci  Potassii  Chloratis^  U.  S.  P.).  Chlorate  of  potassium  must 
on  no  account  be  rubbed  with  sulphur  in  a mortar  or  otherwise, 
friction  of  such  a mixture  resulting  in  violent  explosion. 

Chlorate  of  potassium,  when  heated,  yields  chloride  of  potassium 
and  oxygen,  and  is  the  salt  commonly  employed  in  the  preparation 
of  the  gas  for  experimental  purposes.  But  if  the  action  be  arrested 
when  one-third  of  the  oxygen  has  escaped,  the  residual  salt  is  found 
to  contain  perchlorate  of  potassium  (KCIO^) : — 

2KCIO3  = KCIO,  4-  KCl  4-  0,. 

Chloric  acid  (HCIO3)  may  be  isolated,  but  is  unstable,  quickly 
decomposing  into  chlorine,  oxygen,  and  perchloric  acid ; some  other 
chlorate  [e.g.  KCIO3)  must  therefore  be  used  in  studying  the  reac- 
tions of  the  chloric  radical.  Perchloric  acid  (HCIO4)  may  be 
obtained  by  distilling  perchlorate  of  potassium  with  sulphuric  acid; 
it  is  quite  stable,  and  is  occasionally  administered  in  medicine. 

Table  of  the  Chlorine  Acids, 


Hydrochloric  acid  ....  HCl. 

Hypochlorous  acid  ....  HCIO. 

Chlorous  acid HCIO^. 

Chloric  acid HCIO3 

Perchloric  acid HCIO^. 


The  chloric  radical  is  univalent  (CIO3).  The  acidulous  radicals 
of  the  other  chlorine  acids  are  also  univalent. 

Analytical  Reactions  ( Tests). 

First  Analytical  Reaction. — To  solution  of  a chlorate 
(e.  g.  chlorate  of  potassium)  add  solution  of  nitrate  of  sil- 
ver; no  precipitate  falls,  showing  that  the  chlorine  must 
be  performing  different  functions  to  those  it  possesses  in 
chlorides.  Evaporate  the  solution  to  diyness,  and  place 
the  residue  in  a small  diy  test-tube,  or  at  once  drop  a 
fragment  of  a chlorate  into  a test-tube,  and  heat  strongly; 
oxygen  is  evolved,  and  may  be  recognized  by  its  power  of 
reinflaming  an  incandescent  match  inserted  in  the  tube. 
Boil  the  residue  with  water,  and  again  add  solution  of 
nitrate  of  silver ; a white  precipitate  falls,  having  all  the 


lOD  ATES. 


263 


characters  of  chloride  of  silver,  as  described  under  hydro- 
chloric acid. 

This  is  a trustworthy  test,  and,  omitting  the  recognition  of  the 
oxygen,  may  be  applied  in  the  detection  of  small  quantities  of 
chlorates. 

Second  Analytical  Reaction, — To  a fragment  of  a chlorate 
add  two  or  three  drops  of  strong  sulphuric  acid;  an  explo- 
sive gas  (CI2OJ  is  evolved,  having  a peculiar  odor,  some- 
what like  chlorine,  but  deeper  in  color  than  that  element. 

3KCIO3  -f  H^SO,  = Glfi,  + KCIO,  + K,SO,  -f  H,0. 

Warm  the  upper  part  of  the  test-tube  to  150°  or  200°  F., 
or  introduce  a hot  wire ; a sharp  explosion  ensues,  due  to 
decomposition  of  the  gas,  peroxide  of  chlorine,  into  its 
elements. 

Third  Analytical  Reaction. — Heat  a small  fragment  of 
a chlorate  with  hydrochloric  acid  ; a yellowish-green  ex- 
plosive gas  termed  euclilorine,^  is  evolved.  Its  color  is 
deeper  than  that  of  chlorine,  hence  the  name  (from  fv,  eii,^ 
well,  and  ;^xcopoj,  chldros^  green).  In  odor  it  resembles 
chlorine,  and  is  probably  a mixture  of  that  element  with 
one  of  the  oxides  of  chlorine; 

Fourth  Analytical  Reactioni — Direct  the  blowpipe-flame 
on  to  charcoal  until  a spot  is  red-hot,  and  then  place  on  the 
spot  a fragment  of  a chlorate  ; deflagration  ensues  as  with 
nitrates. 


Bromates. 

Bromates  are  salts  closely  resembling  chlorates  and  iodates.  The 
formula  of  Bromic  acid  is  HBrOg. 

Iodates. 

Iodic  Acid  {HIO3). — Iodine  is  boiled  in  a flask  with  five  times  its 
weight  of  the  strongest  nitric  acid  (sp.  gr.  1.5),  in  a fume-cupboard, 
until  all  action  ceases.  On  cooling,  iodic  acid  separates  in  small 
pyramidal  crystals.  These  are  removed,  the  residual  liquid  evapo- 
rated to  dryness  to  remove  excess  of  nitric  acid,  the  residue  and  the 
first  crop  dissolved  in  a small  quantity  of  boiling  water,  and  the  solu- 
tion sot  aside  to  crystallize. 

lodate  of  Potassium  (KIO3). — Fowder  together  equal  weights  of 
iodine  and  chlorate  of  potassium  ; to  the  mixture  add  twice  its  weight 
of  water  and  about  one-eighth  of  its  weight  of  nitric  acid  ; warm  the 
whole  until  iodine  disappears,  and  evaporate  quite  to  dryness  over  a 
water-bath.  The  residue  dissolved  in  water  forms  “ Solution  of 
lodate  of  Potash,”  B.  P. 


264 


SALTS  OF  ACIDULOUS  RADICALS. 


In  this  reaction  the  small  quantity  of  nitric  acid  furnishes  corre- 
sponding amounts  of  nitrate  of  potassium  and  chloric  acid.  The 
chloric  acid  with  iodine  gives  iodic  acid  and  chlorine,  thus : — 

2HCIO3  + I2  = 2HIO3  + CI2. 

The  iodic  acid  and  some  chlorate  of  potassium  then  yield  chloric  acid 
and  iodate  of  potassium, 

HIO3  + KCIO3  = HCIO3  + KIO3 ; 

and  the  two  reactions  alternate  until  the  whole  of  the  iodine  has  dis- 
placed the  whole  of  the  chlorine. 

Iodate  of  potassium  and  sulphurous  acid  decompose  each  other 
with  elimination  of  iodine  (or  with  formation  of  a blue  color,  if  starch 
be  present).  • Sulphurous  acid  occurring  as  an  impurity  in  acetic 
and  other  acids  may  thus  be  detected. 

2KIO3  + 5H2SO3  = I2  + SH^SO,  + 2KHSO,  H2O. 

Ferric  Iodate,  or  rather  Oxyiodate  (Fe204I03,  is  precipi- 

tated on  adding  solution  of  ferric  chloride  to  solution  of  iodate  of 
potassium. 


QUESTIONS  AND  EXEEOISES. 

462.  How  may  hypochlorous  acids  be  formed? 

463.  What  are  the  relations  of  hypochlorous  acid  to  common 
bleaching  powder? 

464.  By  what  reaction  is  chlorine  eliminated  from  hypochlorites  ? 

465.  State  the  general  reaction  by  which  chlorates  are  formed. 

466.  Give  details  of  the  preparation  of  chlorate  of  potassium. 

467.  Mention  the  properties  of  chlorate  of  potassium. 

468.  What  decompositions  occur  when  chlorate  of  potassium  is 
heated? 

469.  Find  the  molecular  weight  of  chlorate  of  potassium. 

470.  What  weight  of  oxygen  is  yielded  when  1 oz.  of  chlorate  of 
potassium  is  completely  decomposed,  and  how  much  chloride  of  potas- 
sium remains? 

471.  One  hundred  cubic  inches  of  oxygen,  at  60^  F.  and  barometer 

at  30  inches,  weighing  34.203  grains,  and  1 gallon  containing  277 
cubic  inches,  what  weight  of  chlorate  of  potassium  will  be  required 
to  yield  10  gallons  of  the  gas? — Ans.  ounces. 

472.  How  many  cubic  inches  of  oxygen  are  producible  from  1 oz. 
of  chlorate  of  potassium  ? 

473.  Calculate  the  weight  of  chlorate  of  potassium  theoretically 
obtainable  from  100  parts  of  chloride. 

474.  How  is  perchloric  acid  prepared  ? 

475.  Enumerate  the  chlorine  acids. 

476.  How  may  the  presence  of  chlorides  in  chlorates  be  demon- 
strated ? ^ 

477.  Mention  the  tests  for  chlorates. 


ACETATES. 


265 


478.  Give  the  formula  of  peroxide  of  chlorine. 

479.  What  is  euchlorine  ? 

480.  How  may  iodic  acid  be  made  ? 

481.  Describe  the  preparation  ofiodate  of  potassium. 


ACETIC  ACID  AND  OTHER  ACETATES. 

Formula  of  Acetic  Acid  HC2H3O2,  or  HA.  Molecular  weight  60. 

Source. — Acetic  acid  is  said  to  occur  naturally  in  certain  plant 
juices  and  animal  fluids  in  minute  proportions,  but  otherwiae  is  an 
artificial  product.  Much  is  furnished  by  the  destructive  distillation 
of  wood,  hence  the  term  'pyroligneous  acid  for  the  crude  product,  a 
hybrid  word  from  jtv^.pur,  fire,  and  lignum  wood.  This  impure  pro- 
duct, neutralized  by  carbonate  of  sodium,  the  whole  evaporated  and  the 
residue  gently  heated  to  drive  off  the  volatile  tarry  matters,  gives  ace- 
tate of  sodium,  which  after  recrystallization  furnishes  by  distillation 
with  oil  of  vitriol  and  water  acetic  acid  in  a fair  state  of  purity.  In 
Germany  and  France  large  quantities  of  acetic  acid  are  made  by  the 
spontaneous  oxidation  of  the  alcohol  in  inferior  wines,  hence  the  'white- 
and  red-wine  vinegar  [vinegar,  from  the  French  'vin,  wine,  and 
aigre,  sour).  In  England  also  the  domestic  form  of  acetic  acid 
(brown*vinegar)  has  a similar  origin  : infusion  of  malt  and  unmalted 
grain  is  fermented ; and  the  resulting  oxidation  of  its  sugar,  instead 
of  being  arrested  when  the  product  is  an  alcoholic  liquid,  a sort  of 
beer,  is  allowed  to  go  on  to  the  next  stage,  acetic  acid ; it  usually 
contains  from  3 to  6 per  cent  of  real  acetic  acid  (HC2H3O2). 

Vinegars. — The  official  vinegar  [Acetum,  U.  S.  P.)  contains 
nearly  (5.4)  per  cent.  The  so-called  Vinegar  of  Oantharides 
[Acetum  Cantharidis,  B.  P.)  is  a solution  of  the  active  principle 
of  cantharides  in  very  strong  acetic  acid,  not  in  vinegar.  The  Vine- 
gar of  Squill  [Acetum  Scilloe,  B.  P.  and  U.  S.  P.)  is  also  a solution 
of  the  active  principle  of  squill  in  dilute  acetic  acid,  not  in  true  vine- 
gar. The  same  may  be  said  of  Acetum  Lobelice,  U.  S.  P.,  Acetum 
Opii,  U.  S.  P.,  and  Acetum  Sangumarice,  U.  S.  P.  (Vinegar  of 
Bloodroot).  Distilled  vinegar  [Acetum  Destillatum,  U.  S.  P.)  is  a 
form  of  Dilute  Acetic  Acid  not  now  official  in  Great  Britain.  The 
Acetum  Opii  or  Black  Drop  of  America  is  made  from  nutmeg,  saf- 
fron, and  sugar,  as  well  as  Opium  and  Diluted  Acetic  Acid.  In  the 
British  Pharmacopoeia,  vinegar,  except  its  use  for  its  own  sake,  is 
only  employed  in  the  preparation  of  Emplastrum  Cerati  Saponis. 

The  Acetic  Radical. — The  group  of  elements  represented  by  the 
formula  O2H3O2  is  that  characteristic  of  acetic  acid  and  other  ace- 
tates, and  may,  for  convenience  of  study,  be  assumed  to  be  an  acidu- 
lous univalent  radical.  It  has  not  been  isolated,  unless  indeed  a 
compound  of  similar  composition,  resulting  from  the  action  of  perox- 
ide of  barium  on  acetic  anhydride,  is  the  radical  in  question. 

Acetyl. — The  characteristic  grouping  in  acetates,  C2H3O2,  is  fre- 
quently considered  to  contain,  rather  than  to  be,  a radical — C2H3O, 
termed  acetyl.  Acetates  may  be  made  to  yield  a body  having  the 
23 


266 


SALTS  OF  ACIDULOUS  RADICALS. 


composition  C.^H^OCl,  which  is  regarded  as  chloride  of  acetyl ; from 
this  may  be  obtained  acetic  anhydride  (C^HgOg),  which  by  absorbing 
water  becomes  acetic  acid. 


C2H3O  1 

Cl  I 

Chloride  of 
acetyl. 


C2H3O 

C2H3O 

Acetic 

anhydride. 


0 


CAOjo 

Acetic  acid. 


0,H,0|o 

Metallic 

acetates. 


The  relation  of  acetic  acid  to  alcohol  will  be  evident  from  the  fol- 
lowing equation  representing  empirically  the  formation  of  the  acid  : — 


C.,HgO  + O2  = C^H^O,  + H.,0 

Alcohol.  Acetic  acid. 


Acetates  in  aqueous  solution  are  liable  to  decomposition.  In  solu- 
tion of  acetate  of  morphia  a myceloid  growth  occasionally  forms,  ace- 
tic acid  disappears,  and  morphia  is  deposited.  Solution  of  acetate 
of  ammonium  is  liable  to  a similar  change,  gradually  becoming  alka- 
line. 


Synthetical  Reaction, 

Acetic  Acid. 

Synthetical  Reaction,  — To  a few  grains  of  acetate  of 
sodium  in  a test-tube  add  a little  water  and  some  sulphuric 
acid,  and  heat  the  mixture  ; acetic  acid  is  evolved,  and  may 
be  condensed  by  a bent  tube  adapted  to  the  test-tube  by  a 
cork  in  the  usual  way. 

Acetic  Acid. — This  is  the  process  by  which  acetate  of  sodium  or 
calcium  (the  neutralized  products  of  the  distillation  of  wood)  is  made 
to  yield  acetic  acid  on  the  large  scale.  'As  with  nitric  and  hydro- 
chloric acids,  the  loose  term  “ acetic  acid”  is  that  usually  applied  to 
aqueous  solutions  of  acetic  acid.  The  Acidum  Aceticum,  B.  P., 
contains  nearly  33  per  cent,  of  real  acid — that  is,  of  HC2H3O.2 ; for  it 
contains  only  28  per  cent,  of  acetic  anhydride  (C4Hg03).  Its  specific 
gravity  is  1.044,  the  specific  gravity  of  Acidum  Aceticum^  U.  S.  P., 
being  1.047.  Acidum  Aceticum  Dilutum,  B.  P.  and  U.  S.  P.,  con- 
tains per  cent,  of  HC2II3O.2.  Glacial  acetic  acid  (HC2H3O2) 
contains  no  water.  It  solidifies  to  a crystalline  mass  at  tempera- 
tures below  63*^  F.,  hence  the  appellation  glacial  (from  glades,  ice). 
Good  commercial  glacial  acetic  acid  [Acidum  Aceticum  Glaciale, 
B.  P.)  does  not  contain  more  than  1 per  cent,  of  water,  corresponding  | 
to  84.15  per  cent,  of  acetic  anhydride  ; it  solidifies  at  34^,  and  again  I 
liquefies  at  48^:  its  specific  gravity  is  1.065.  Although  water  is  i 
lighter  than  this  acetic  acid,  yet  the  addition  of  water  at  first  renders  j 
the  acid  heavier ; evidently  therefore  condensation,  or  contraction  in  1 
bulk,  occurs  on  mixing  the  liquids  : after  10  per  cent,  has  been  added,  j 
the  addition  of  more  water  produces  the  usual  effect  of  dilution  of  a • 
heavy  liquid  by  a lighter,  namely,  reduction  of  relative  weight. 
This  matter  will  be  better  understood  after  the  subject  of  specific 
gravity  has  been  studied.  | 


ACETATES. 


26Y 


The  following  equation  is  expressive  of  the  above  reaction  : — 


NaC,H302  + H,SO,  = + NaHSO, 

Acetate  of  Sulphuric  Acetic  acid.  Acid  sulphate 

sodium.  acid.  of  sodium. 

or,  assuming  the  existence  of  acetyl  (O^HgO)  in  acetic  acid,  and  a 
corresponding  radical  sulphuryl  (SO2)  in  sulphuric  acid. 


, S04q  _ 0^01  Q so,  u . 

Na  i ^ + H J “ H I ^ + NaH  J ’ 


or,  thirdly,  on  the  assumption  that  salts  contain  the  oxide  of  a basy- 
lous  radical  united  with  the  anhydride  of  an  acid  (the  old  view  under 
which  such  names  as  acetate  of  soda  were  formed), 

Na20,0,He03  + 2H20,S03  = Na20,H20,2S03  + H20,0,H603. 


Note  on  the  Constitution  of  Salts. 


Which  of  these  three  equations,  or,  more  broadly,  which  of  the 
three  views  of  the  constitution  of  salts  illustrated  by  the  equations, 
is  correct,  it  is  impossible  to  say.  Whether  it  is  C.2H3O.2,  O2H3O, 
or  C^Hg03,  which  migrates  from  one  acetic  compound  to  another, 
whether  it  is  SO4,  SO2,  or  SO3,  which  migrates  from  one  sulphuric 
compound  to  another,  and  so  on  with  other  acidulous  groupings, 
cannot  at  present  be  determined.  There  are  strong  objections  to 
each  view  ; and  possibly  neither  is  right.  Either  the  given  radicals 
cannot  be  isolated,  or  application  of  the  forces  of  heat,  light,  and 
electricity  do  not  confirm  views  arrived  at  by  the  results  of  operations 
with  the  chemical  force  ; or  a salt  comes  to  be  regarded  as  having  so 
large  a number  of  constituent  parts  that  the  view,  however  true, 
breaks  down  in  practice  from  the  sheer  inability  of  the  mind  to 
grasp  the  complicated  analogies  involved.  Yet  for  the  purposes  of 
description,  study,  and  conversation  some  system  must  be  adopted. 
Let  the  first,  then,  be  generally  taken,  over-reliance  on  it  being 
checked  by  the  use  of  general  instead  of  special  names  for  the  hypo- 
thetical radicals,  and  other  systems  be  employed  in  certain  cases. 
(See  also  p.  253.) 

Impurity. — Acetic  acid  often  contains  sulphurous  acid.  The 
methods  by  which  this  impurity  is  detected  are  described  on  pages 
264  and  274. 


Analytical  Reactions  ( Tests). 

First  Analytical  Reaction. — To  an  acetate  add  sulphuric 
acid  and  heat  the  mixture  ; acetic  acid,  recognized  by  its 
odor,  is  evolved. 

Note  1. — Iodine,  sulphurous  acid,  and  other  substances  of  power- 
ful odor  mask  that  of  acetic  acid  ; they  must  be  removed,  therefore, 
usually  by  precipitation  or  oxidation,  before  applying  this  test. 

Note  2. — It  will  be  noticed  that  this  reaction  is  identical  with  the 
previous  one ; it  has  synthetical  or  analytical  interest,  according  to 
the  object  and  method  of  its  performance. 


268 


SALTS  OP  ACIDULOUS  RADICALS. 


Second  Analytical  Beaction. — Repeat  the  above  action,  a 
few  drops  of  spirit  of  wine  being  first  added  to  the  acetate  ; 
acetic  ether  (acetate  of  ethyl,  €21150311302)5  also  of  charac- 
teristic odor,  is  evolved. 

The  basylous  radical  ethyl  (C2H5)  will  be  referred  to  subsequently. 

Third  Analytical  Reaction. — Heat  a fragment  of  a dry 
acetate  in  a test-tube,  and  again  notice  the  odor  of  the 
gaseous  products  of  the  decomposition,  among  them  is 
acetone  (C^HgO),  the  smell  of  which  is  characteristic.  Car- 
bonate of  the  metal  remains  in  the  test-tube. 

Fourth  Analytical  Reaction. — To  a solution  of  an  acetate, 
made  neutral  by  the  addition  of  acid  or  alkali,  as  the  case 
may  be,  add  a few  drops  of  neutral  solution  of  perchloride 
of  iron ; a deep-red  liquid  results,  owing  to  the  formation 
of  ferric  acetate  (Fe26C2H302). 

Note. — It  will  be  noticed  that  the  formation  of  characteristic  pre- 
cipitates, the  usual  method  of  removing  radicals  from  solution  for 
recognition,  is  not  carried  out  in  the  qualitative  analysis  of  acetates. 
This  is  because  all  acetates  are  soluble.  Acetate  of  silver  ( AgC2H302) 
and  mercurous  acetate  (HgC2H302)  are  only  sparingly  soluble  in  cold 
water,  but  the  fact  can  seldom  be  utilized  in  analysis.  Hence  pecu- 
liarities of  color  and  odor,  the  next  best  characters  on  which  to  rely, 
are  adopted  as  means  by  which  acetates  may  be  detected.  Acetates, 
like  other  organic  compounds,  char  when  heated  to  a high  tempera- 
ture. 


QUESTIONS  AND  EXERCISES. 

482.  What  is  the  formula  of  acetic  acid  ? 

483.  State  the  relation  of  acetic  acid  to  other  acetates. 

484.  What  is  the  molecular  weight  of  acetic  acid  V 

485.  Name  the  sources  of  acetic  acid. 

486.  What  is  pyroligneous  acid  ? 

487.  From  what  compound  is  the  acetic  acid  of  foreign  and  Eng- 
lish vinegar  immediately  derived  ? 

488.  How  much  real  acid  is  contained  in  official  vinegar  ? 

489.  What  is  the  nature  of  the  “ Vinegars”  of  Pharmacy  ? 

490.  How  may  acetic  acid  be  obtained  from  acetate  of  sodium  ? 

491.  How  much  real  acid  is  contained  in  the  official  acetic  acid  ? 

492.  Mention  Ihe  strength  of  commercial  glacial  acetic  acid. 

493.  Give  three  or  more  views  of  the  constitution  of  acetates, 
illustrating  each  by  formulae. 

494.  Enumerate  the  tests  for  acetates, 


SULPHIDES. 


269 


HYDROSULPHURIC  ACID  AND  OTHER  SULPHIDES. 

Formula  of  Hydrosulphuric  Acid  H2S.  Molecular  weight  34. 

Source  mid  Varieties  of  Sulphur. — The  acidulous  radical  of  hy- 
drosulphuric  acid,  sulphydric  acid,  or  sulphuretted  hydrogen,  and 
other  sulphides,  is  the  element  sulphur  (S).  It  occurs  in  nature  in 
combination  with  metals,  as  already  stated  in  describing  the  ores  of 
some  of  the  metals,  and  also  in  the  free  state.  Most  of  the  sulphur 
used  in  medicine  is  imported  from  Sicily,  where  it  occurs  chiefly  asso- 
ciated with  blue  clay.  It  is  purified  by  fusion,  sublimation,  or  distil- 
lation. Melted  and  poured  into  moulds,  it  constitutes  a crystalline 
mass  termed  roll  sulphur.  If  distilled  and  the  vapor  carried  into 
large  chambers,  so  that  it  may  be  rapidly  condensed,  the  crystals  are 
so  minute  as  to  give  the  sulphur  a pulverulent  character;  this  is  sub- 
limed sidphur  {Sulphur  Sublimatum,  B.  P.  and  U.  S.  P.)  or  flowers 
of  sulphur : the  same  washed  constitutes  Sulphur  Lotum,  U.  S.  P. 
4'he  third  common  form,  milk  of  sulphur,  will  be  noticed  subse- 
quently. Sulphur  also  occurs  in  nature  in  combination  as  a constitu- 
ent of  animal  and  vegetable  tissues,  as  sulphurous  acid  gas  (SQ.^)  in 
volcanic  vapors,  and  as  sulphuretted  hydrogen  in  some  waters,  as 
those  of  Harrogate. 

Plastic  sulphur  is  one  of  the  allotropic  varieties  of  the  element, 
obtained  on  heating  sulphur  considerably  beyond  its  melting-point 
and  pouring  into  cold  water. 

Quantivalence. — Sulphur  is  sexivalent,  as  seen  in  sulphuric  anhy- 
dride (SO3),  a substance  which  will  be  noticed  under  sulphuric  acid. 
It  also  occasionally  exhibits  quadrivalent  (SO2)  and  still  oftener 
bivalent  affinities  (H2S). 

Molecular  weight. — At  very  high  temperatures  sulphur  follows  the 
rule  that,  under  similar  circumstances  of  heat  and  pressure,  atomic 
weights  (in  grammes,  grains,  etc.)  of  elements  occupy  equal  volumes 
of  vapor ; its  formula  therefore  is  83,  and  molecular  weight  64.  At 
lower  temperatures  the  volume  weighs  three  times  as  much  as  it 
should  do  if  following  usual  laws,  and  then  the  molecule  would  appear 
to  contain  six  atoms  (S^). 

Acid  Salts. — Sulphur  (S")  being  the  first  acidulous  radical  of 
bivalent  activity  met  with  in  these  sections  on  acids,  it  is  desirable 
here  to  draw  attention  to  a new  class  of  salts  to  which  such  a radical 
will  generally  give  rise.  These  are  acid  salts,  which  are  intermediate 
between  normal  salts  and  acids.  Univalent  radicals  with  an  atom 
of  hydrogen  give  an  acid,  and  with  an  atom  of  other  basylous  radi- 
cals an  ordinary  or  normal  salt.  But  bivalent  radicals,  from  the  fact 
that  they  give  with  two  atoms  of  hydrogen  an  acid,  and  with  two 
atoms  of  univalent  metals  a normal  salt,  may  obviously  give  inter- 
mediate bodies  containing  one  atom  of  hydrogen  and  one  atom  of 
metal ; these  are  appropriately  termed  acid  salts : they  are  neither 
normal  acids  nor  normal  salts,  but  acid  salts.  (Examples : — 
KHCO3,  NaHSO,,  KHC4H4O,,  Na2HPO„  CuHAsO^,  CaH,2PO,.) 
Whether  or  not  these  salts  give  an  acid  reaction  with  blue  litmus 
paper  depends  on  the  strength  of  the  respective  radicals.  Usually 

23* 


270 


SALTS  OF  ACIDULOUS  RADICALS. 


they  do  redden  the  test-paper,  but  sometimes  not;  thus  the  acid  sul 
phide  or  sulphydrate  of  potassium  (KHS),  of  sodium  (NallS),  or  am- 
monium (AmllS)  has  alkaline  properties.* 

Synthetical  Reactions. 

Sulphuretted  Hydrogen. 

First  Synthetical  Reaction. — The  preparation  of  sulphu- 
retted hydrogen This  operation  was  described  on  page 

81,  and  probably  has  already  been  studied  by  the  reader. 

Precipitated  Sulphur. 

Second  Synthetical  Reaction. — Prepare  the  variety  of  the 
radical  of  sulphides  known  as  Precipitated  Sulphur  {Suh 
phur  Fraecipitatum^  B.  P.  and  XJ.  S.  P.)  or  7nz7^  of  sulphur 
by  boiling  a few  grains  of  flowers  of  sulpliur  (5  parts)  with 
slaked  lime  (3  parts)  (10  parts  U.  S.  P.)  and  some  water 
(20  parts)  in  a test-tube  (larger  quantities  in  an  evapo- 
rating-basin), filtering,  and  (reserving  a small  portion  of 
the  filtrate)  adding  dilute  hydrochloric  acid  until  the  well- 
stirred  liquid  has  a faint  acid  reaction  on  test-paper;  sul- 
phur is  precipitated,  and  maybe  collected  on  a filter,  washed, 
and  dried  (at  about  1 20°).  Excess  of  acid  must  be  avoided, 
or  hydrosulphyl,  the  liquid  persulphide  of  hydrogen  (H^S.^) 
will  be  formed,  causing  the  particles  of  sulphur  to  aggre- 
gate to  a gummy  mass. 

This  is  the  process  of  the  Pharmacopoeias.  Polysulphide  of  cal- 
cium and  hyposulphite  of  calcium  are  formed  : — 

SCaH^O^  + 6S,  = 2CaS5  -f  CaS.Og  4-  3H,0 

Hydrate  of  Sulphur.  Folysulpbide  Hyposulphite  Water. 

calcium.  of  calcium.  of  calcium. 

On  adding  the  acid,  both  salts  are  decomposed  and  sulphur  sepa- 
rates : — 

2CaS.  -f-  CaS^Og  -f  6HC1  = SCaCl^  + 311., 0 -f  6S., 

Poly.*5ulphide  Hyposulphite  Hydrochloric  Chloride  of  Water.  Sulphur, 
of  calcium.  of  calcium.  acid.  calcium. 

Polysulphide  of  calcium  alone  would  yield  sulphuretted  hydrogen 
as  well  as  sulphur  on  the  addition  of  acid.  Hyposulphite  of  calcium 
alone  would  yield  sulphurous  acid  gas  as  well  as  sulphur.  If  these 

* Some  chemists  regard  these  siilphydrates  as  compounds  of  basy- 
lous  radicals  with  liS,  a univalent  grouping  termed  hydrosulphyl  (per- 
sulphide of  hydrogen,  just  as  hydrates  are  similarly  viewed  as 

compounds  of  the  univalent  radical  hydroxyl  (HO)  (peroxide  of  hy- 
drogen, H2O.,) — 11,8  becoming  UlIS  or  fills  (hydrosulphylide  of  hydro- 
gen), and  H.,0  becoming  llHO  or  HHo  (hydioxylide  of  hydrogen). 


SULPHIDES. 


2n 

gases  are  formed  in  the  above  operation,  they  at  once  react  and  give 
sulphur  and  water,  very  little,  if  any,  sulphuretted  hydrogen  escaping. 

+ 280.,  = 38^  + 4H2O. 

Impure  Precipitated  Sulphur. — To  a sulphur  solution 
prepared  as  before  (or  to  the  reserved  portion)  add  sul- 
phuric acid ; the  precipitate  is  in  this  case  largely  mixed 
with  sulphate  of  calcium  : — 

-f  CaSA  + 3H,S0,  = SCaSO,  + 3H,0  + 68^ 

Polysulphide  Hyposulphite  Sulphuric  Sulphate  of  Water.  Sulphur, 
of  calcium.  of  calcium.  acid.  calcium. 

Place  a little  of  each  of  these  specimens  of  precipitated 
sulphur  with  a drop  of  the  supernatant  liquid  on  a strip  of 
glass,  cover  each  spot  with  a piece  of  thin  glass,  and  exa- 
mine the  precipitates  under  a microscope  ; the  pure  sulphur 
will  be  found  to  consist  of  minute  grains  or  globules,  the 
impure  to  contain  comparatively  large  crystals  (sulphate  of 
calcium). 

Note. — By  far  the  larger  proportion  of  precipitated  sulphur  met 
with  in  trade  still  (1873)  contains,  to  the  knowledge  of  the  Author, 
sulphate  of  calcium,  most  specimens  affording  two-thirds  of  their 
weight  of  that  substance.  Moreover,  this  adulteration  has  been  so 
persistently  practised  that  many  persons  have  become  sufficiently 
accustomed  to  the  satiny  appearance  of  the  impure  article  to  regard 
the  pure  article  with  suspicion,  sometimes  refusing  to  purchase  it. 

To  ascertain  the  amount  of  sulphate  of  calcium  in  an  impure  speci- 
men of  precipitated  sulphur,  place  a weighed  quantity  in  a tared 
crucible  and  heat  till  no  more  vapors  are  evolved.  The  weight  of 
the  residual  anhydrous  sulphate  of  calcium  (Ca804=136),  with  one- 
fourth  thereof  added,  is  the  amount  of  crystalline  sulphate  of  calcium 
(Ca804,  2H20  = 172)  present  in  the  original  quantity  of  impure 
sulphur. 

Pharmacists  should  refuse  all  parcels  of  sulphur  which  yield  a 
white  ash  when  a little  is  burnt  off  on  the  end  of  a table-knife  or 
spatula.  (No  more  damage  is  done  to  the  steel  than  a rub  on  a 
knife-board  will  remove.) 

Analytical  Reactions  ( Tests). 

To  a sulphide  add  a few  drops  of  h^^drocdiloric  acid  ; 
sulphuretted  hydrogen  will  probably  be  evolved,  well 
known  by  its  smell.  If  the  sulphide  is  not  acted  upon  by 
the  acid,  or  if  free  sulphur  be  under  examination,  mix  a 
minute  portion  with  a fragment  of  solid  caustic  potash  or 
soda,  and  fuse  on  a silver  coin  or  spoon.  When  cold, 
place  a drop  of  dilute  hydrochloric  acid  on  the  spot,  sul- 
phuretted hydrogen  is  evolved,  and  a black  stain,  due  to 
sulphide  of  silver  (Ag^S),  left  on  the  coin. 


272 


SALTS  OF  ACIDULOUS  RADICALS. 


Other  sulphur  reactions  may  be  adopted  as  tests,  but  the  above 
are  sufficient  for  all  ordinary  purposes.  The  most  convenient  re- 
agent for  detecting  sulphur  in  solution  of  ammonia  is  ammonio-sul- 
phate  of  copper,  which  gives  a black  precipitate  of  sulphide  of  copper 
if  sulphur  be  present. 

The  Iodide  of  Sulphur  (S.J2)  lias  been  mentioned  under  “ Iodine.” 
A chloride  (S2CI2)  and  bromide  (S2Br2)  may  also  be  formed  from 
their  elements.  A mixture  of  sulphur  and  chloride  of  sulphur  is 
sometimes  met  with  under  the  name  of  hypochloride  of  sulphur. 


QUESTIONS  AND  EXEKCISES. 

495.  In  what  form  does  sulphur  occur  in  nature  ? 

496.  State  the  modes  of  preparation  of  the  three  chief  commercial 
varieties  of  sulphur. 

497.  To  what  extent  does  the  atom  of  sulphur  vary  in  quantiva- 
lence  ? 

498.  State  the  relations  of  acid  salts  to  acids  and  to  normal  salts. 

499.  Define  sulphides  and  sulphydrates. 

500.  Describe  the  preparation  of  sulphuretted  hydrogen. 

501.  What  are  the  characters  of  pure  precipitated  sulphur? 

502.  Give  equations  explanatory  of  the  reactions  which  occur  in 
precipitating  sulphur  according  to  the  official  process. 

503.  Describe  the  microscopic  test  for  impure  precipitated  sulphur. 

504.  Mention  a ready  physical  method  of  detecting  the  adultera- 
tion of  precipitated  sulphur  by  sulphate  of  calcium. 

505.  Mention  the  tests  for  sulphides,  and  the  character  by  which 
sulphurretted  h^-drogen  is  distinguished  from  other  sulphides. 

506.  How  are  sulphides  insoluble  in  acids  tested  for  sulphur  ? 

507.  Give  a method  for  the  detection  of  a trace  of  sulphur  in  solu- 
tion of  ammonia. 


SULPHUROUS  ACID  AND  OTHER  SULPHITES. 

Formula  of  sulphurous  acid  H2SO3.  Formula  of  sulphurous  acid  gas 
or  sulphurous  anhydride,  commonly  termed  sulphurous  acid,  ISO2. 
Molecular  weight  of  sulphurous  acid  82  ; of  the  gas  64. 

AVhen  sulphur  is  burned  in  the  air  it  combines  with  oxygen  and 
forms  sulphurous  acid  gas  (SO2),  more  correctly  termed  sulphurous 
anh3xlride,  or  commonly,  but  erroneously,  sulphurous  acid.  It  is  a 
pungent,  colorless  gas,  readily  liquefied  on  being  passed  through  a 
tube  externally  cooled  by  a freezing-mixture  composed  of  two  parts 
of  well-powdered  ice  (or,  better,  snow)  with  one  part  of  common  salt. 
If  sulphurous  acid  gas  becomes  moist  or  is  passed  into  water,  heat  is 
evolved  and  true  sulphurous  acid  (II2SO3)  formed.  The  latter  body 
may  be  obtained  in  crystals  ; but  it  is  very  unstable,  and  hence  the 
properties  of  the  sulphurous  radical  must  be  studied  under  the  form 


SULPHITES. 


213 


of  some  other  sulphite;  sulphite  of  calcium  (CaSOg),  or  sulphite  of 
sodium  (Na2S03),  may  be  used  for  the  purpose. 

Quantivalence. — The  radical  of  the  sulphites  is  bivalent  (SO3"), 
and  hence  forms  acid  sulphites,  such  as  acid  sulphite  of  potassium 
(KHSO3)  and  normal  sulphites,  such  as  sulphite  of  sodium  (Na2S03)* 

Note  on  Nomenclature. — The  sulphites  are  so  named  from  the 
usual  rule,  that  salts  corresponding*  with  acids  whose  names  end  in 
ous  have  a name  ending  in  ite.  They  are  generally  made  by  pass- 
ing sulphurous  acid  gas  over  moist  oxides  or  carbonates — in  the 
latter  case  carbonic  acid  gas  escaping. 

Synthetical  Reaction. — To  a few  drops  of  sulphuric  acid 
in  a test-tube  add  a piece  of  charcoal  and  apply  heat;  sul- 
phurous acid  gas  is  evolved,  and  may  be  conveyed  by  a 
bent  tube  into  a small  quantity  of  cold  water  in  another 
test-tube.  Larger  quantities  may  be  made  in  a Florence 
flask.  The  product  is  the  Aciduni  Sulphurosnm^  B.  P.  and 
XJ.  S.  P.  It  is  said  to  contain,  if  saturated,  nearly  12 
(11.79)  per  cent,  of  sulphurous  acid  (H^SOg)  or  about  9 
(9.2)  per  cent,  of  the  gas  (SO^).  The  process  is  also  that 
described  in  the  Pharmacopoeia,  except  that  the  gas  is 
purified  by  passing  through  a small  wash-bottle  before  final 
collection.  Specific  gravity  1.04  (1.035,  IT.  S.  P.). 

Sulphurous  acid  may  also  be  made  by  boiling  copper, 
mercury,  or  iron  with  sulphuric  acid,  sulphates  of  the 
metals  being  formed.  Also  by  boiling  sulphur  with  sul- 
phuric acid. 

If  in  this  process  the  water  were  replaced  by  solutions  of  or  solid 
metallic  oxides  or  carbonates,  sulphites  of  the  various  metals  would 
be  formed.  The  formula  of  sulphite  of  potassium  {Potassu  Sulphis, 
U.  S.  P.)  is  K2S03,2E[2f^ ; of  sulphite  of  sodium  (Sodu  Sulphis, 
U.  S.  P.)  Na2S03,7H20  ; of  the  bisulphite  or  acid  sulphite  NaH  S03. 
Under  the  name  of  antichlor  the  former  is  used  for  removing  traces  of 
chlorine  from  paper  pulp.  Sulphite  of  magnesium  crystallized  from 
a strong  solution  of  sulphurous  acid  in  water  has  the  formula 
MgS03,6H20. 

4H2SO,  + C2  = 2CO2  + 4H2O  -f  4SO2 

Sulphuric  Carbon  Carbonic  Water.  Sulphurous 

acid.  (charcoal).  acid  gas.  acid  gas. 

SO2  + IT,0  = H2SO3 
Sulphurous  Water,  Sulphurous 
acid  gas.  acid. 


Analytical  Reactions  ( Tests). 

First  Analytical  Reaction. — To  a sulphite  (of  sodium,  for 
instance — made  by  passing  sulphurous  acid  into  solution 
of  carbonate  of  sodium)  add  a drop  or  two  of  dilute  hydro- 


274  SALTS  OF  ACIDULOUS  RADICALS. 

chloric  acid;  sulphurous  acid  gas  escapes,  known  by  its 
peculiar  pungent  smell. 

This  smell  is  the  same  as  that  evolved  on  burning  lucifer  matches 
that  have  been  tipped  with  sulphur.  It  is  due,  probably,  not  to  the 
gas  (SO2),  but  to  sulphurous  acid  (HgSOg)  formed  by  the  union  of 
sulphurous  acid  gas  with  either  the  moisture  of  the  air  or  that  on 
the  surface  of  the  mucous  membrane  of  the  nose.  It  is  highly  suffo- 
cating. 

Second  Analytical  Reaction. — To  a sulphite  add  a little 
water,  a fragment  or  two  of  zinc,  and  then  hydrochloric 
acid  ; sulphuretted  hydrogen  will  be  evolved,  known  by  its 
putrid  odor  and  action  on  a piece  of  paper  placed  like  a 
cap  on  the  mouth  of  the  test-tube,  and  moistened  with  a 
drop  of  solution  of  acetate  of  lead,  black  sulphide  of  lead 
being  formed.  Sulphurous  acid  may  be  detected  in  acetic 
acid,  or  in  hydrochloric  acid,  by  this  test. 

H.SOg  + Hg  = H^S  + 3II2O. 

Other  Analytical  Reactions. 

To  solutions  of  neutral  sulphites  add  nitrate  or  chloride 
of  barium,  chloride  of  calcium,  or  nitrate  of  silver ; in 
each  case  white  sulphites  of  the  various  metals  are  precipi- 
tated. The  barium  sulphite  is  soluble  in  weak  hydrochloric 
acid ; but  if  a drop  or  two  of  chlorine-water  is  first  added, 
barium  sulphate  is  formed,  which  is  insoluble  in  acids.  The 
other  precipitates  are  also  soluble  in  acids.  The  silver  sul- 
phite is  decomposed  on  boiling,  sulphuric  acid  being  formed, 
and  metallic  silver  set  free. 

To  recognize  the  three  radicals  in  an  aqueous  solution  of  sulphides, 
sulphites,  and  sulphates,  add  chloride  of  barium,  filter,  and  wash  the 
precipitate.  In  the  filtrate  sulphides  are  detected  by  the  sulphu- 
retted hydrogen  involved  on  adding  an  acid.  In  the  precipitate 
sulphites  are  detected  by  the  odor  of  sulphurous  acid  produced  on 
adding  hydrochloric  acid,  and  sulphates  by  their  insolubility  in  the 
acid. 


QUESTIONS  AND  EXERCISES. 

508.  What  are  the  differences  between  sulphurous  acid  and  sul- 
phurous acid  gas,  sulphites  and  acid  sulphites  ? 

509.  State  the  characters  of  sulphurous  acid  gas. 

510.  IIow  is  the  official  Sulphurous  Acid  prepared  ? 

511.  By  what  test  may  sulphurous  acid  be  recognized  in  acetic 
acid  ? 

512.  Give  a method  by  which  sulphites  may  be  detected  in  pre- 
sence of  sulphides  and  sulphates. 


SULPHATES. 


275 


SULPHURIC  ACID  AND  OTHER  SULPHATES. 


Formula  of  Sulphuric  Acid  H2SO4.  Molecular  Weight  98. 

Sulphates  occur  in  nature  ; but  the  common  and  highly  important 
hydrogen  sulphate,  sulphuric  acid,  is  made  artificially. 

Preparation  of  Sulphuric  Acid,  General  Nature  of  the  Process, 
— Sulphur  itself,  or  sometimes  the  sulphur  in  iron  pyrites,  is  first 
converted  into  sulphurous  acid  gas  by  burning  in  air,  and  this  gas,  by 
moisture  and  oxygen,  into  sulphuric  acid  (S02+H204-0=H2S04). 

Details  of  the  process. — The  oxygen  necessary  to  oxidize  the  sul- 
phurous acid  gas  cannot  directly  be  obtained  from  air,  but  indirectly, 
the  agency  of  nitric  oxide  (NO)  being  employed — this  gas  becoming 
nitric  peroxide  (NO2)  by  action  of  the  air,  and  the  nitric  peroxide 
again  becoming  nitric  oxide  by  the  action  of  the  sulphurous  acid  gas, 
and  so  on.  A small  quantity  of  nitric  oxide  gas  will  in  this  way  act 
as  carrier  of  oxygen  from  the  air  to  very  large  quantities  of  sulphur- 
ous acid. 

The  following  equations  represent  the  successive  steps  : — 

S2  + 2O2  = 2SO2 

Sulphur.  Oxygen  Sulphurous 
(of  the  air).  acid  gas. 

SO2  4-  H2O  = H2SO3 

Sulphurous  Water.  Sulphurous 

acid  gas.  acid. 

2NO  -f  O2  = 2NO2 

Nitric  Oxygen  Nitric 

oxide.  (of  the  air),  peroxide. 

B,SO,  + NO,  = H,SO,  + NO 

Sulphurous  Nitric  Sulphuric  Nitric 

acid.  peroxide.  acid.  oxide. 


On  the  large  scale  the  sulphurous  acid  gas  is  produced  by  burning 
sulphur  in  furnaces;  it  is  carried,  togethev  with  the  nitric  vapors, 
by  fiues  into  leaden  chambers,  where  jets  of  steam  supply  the  neces- 
sary moisture  ; the  steam  also,  condensing,  prevents  other  reactions. 
The  resulting  dilute  sulphuric  acid  is  concentrated  by  evaporation  in 
leaden  vessels. 

The  nitric  peroxide  is  in  the  first  instance  obtained  from  nitric 
acid,  and  this  from  nitrate  of  potassium  or  sodium  by  the  action  of  a 
small  quantity  of  the  sulphuric  acid  of  a previous  operation. 


2NaN03 

Nitrate  of 
sodium. 


+ H,SO, 

Sulphuric 

acid. 


Na^SO^  + 2HNO5 

Sulphate  of  Nitric 

sodium.  acid. 


3H2SO3  + 2HNO3 

Sulphurous  Nitric 

acid.  acid. 


3ELSO4  -h  H,0  + 2NO 

Sulphuric  Water.  Nitric 

acid.  oxide. 


Other  processes. — Sulphuric  acid  may  be  obtained  by  other  pro- 
cesses, as  by  distilling  the  sulphate  of  iron  resulting  from  the  natural 
oxidation  of  iron  pyrites  by  air ; but  it  is  seldom  so  made  at  the 
present  day.  The  sulphate  of  ir.on  was  formerly  called  green  vitriol, 
and  the  distilled  product  oil  of  vitriol,  in  allusion  to  its  consistence 
and  origin. 


276 


SALTS  OF  ACIDULOUS  RADICALS. 


Experiment. — For  purposes  of  practical  study,  a small  quantity 
may  be  made  by  passing,  a,  sulphurous  acid  gas  (p.  272),  h,  nitric 
oxide  (p.  257),  c,  air  (forced  through  by  aid  of  bellows  or  a gas- 
holder), and,  occasionally,  d,  steam  (generated  in  a Florence  flask) 
through  glass  tubes,  nearly  to  the  bottom  of  a two-  or  three-quart 
•flask,  . 

S0.,  + H,0  = H2S03;  I 2Nt)  + 02  = 2N0,; 

H2SO3  -f  NO2  = H^SO,  -f  NO. 

A slow  current  of  sulphurous  acid  gas,  air,  and  steam,  and  a small 
quantity  of  nitric  oxide,  will  furnish,  in  the  course  of  a few  minutes, 
enough  sulphuric  acid  for  recognition  by  the  first  of  the  following 
analytical  reactions. 

Purification. — Sulphuric  acid  may  contain  arsenic,  nitrous  com- 
pounds, and  salts.  Arsenic  may  be  detected  by  the  hydrogen-test  (p. 
149),  nitrous  compounds  by  powdered  sulphate  of  iron  (which  ac- 
quires a violet  tint  if  they  are  present),  and  salts  by  the  residue  left 
on  boiling  a little  to  dryness  in  a crucible  in  a fume-chamber.  If 
only  nitrous  compounds  are  present,  the  acid  may  be  purified  by 
heating  with  about  half  per  cent,  of  sulphate  of  ammonium — water 
and  nitrogen  being  produced  (Pelouze).  If  arsenic  occurs,  boil  with 
a small  quantity  of  hydrochloric  acid,  which  converts  the  arsenic  into 
chloride  of  arsenicum ; or  heat  with  a little  nitric  acid,  which  con- 
verts arsenious  (As.^Og)  into  arsenic  anhydride  (As.^05),  sul- 

phate of  ammonium,  and  distil  in  a retort  containing  pieces  of  quartz 
and  heat  by  an  annular-shaped  burner  (to  prevent  “ bumping”).  The 
arsenic  anhydride  remains  in  the  retort.  (Arsenious  anhydride  would 
be  carried  over  with  the  sulphuric-acid  vapors.)  By  distillation  the 
acid  is  also  purified  from  salts  (such  as  NaHSO^)  which  are  not 
volatile. 

Quantivalence. — The  sulphuric  radical  being  bivalent  (SO/'),  acid 
as  well  as  normal  sulphates  may  exist.  Acid  sulphate  of  potassium 
(KHSO4)  is  an  illustration  of  the  former,  sulphate  of  sodium  (Na.^SOJ 
of  the  latter ; double  sulphates  may  also  occur,  such  as  that  of  potas- 
sium and  magnesium  (K2SO4,  MgSO^,  6H2O).  Sulphates  generally 
contain  water  of  crystallization. 

Pure  sidphuric  acid  (H2SO4)  is  of  specific  gravity  1.848.  The 
best  “ oil  of  vitriol”  of  commerce,  a colorless  liquid  of  oily  consis- 
tence, is  of  specific  gravity  1.843,  and  contains  96,8  per  cent,  of  real 
acid  (H2SO4).  This  is  the  Acidum  Sulphuricum,  B.  P.  and  U.  S. 
P.  The  Acidum  Sulphuricum  Dilutum,  B.  P.,  sp.  gr.  1.094  (U. 
S.  P.  1.082)  contains  about  I3J-  (13  64)  per  cent,  of  acid  (II2SO4) ; 
and  the  Acidum  Sidphuricum  Aromaticum,  B.  P.  and  U.  S.  P.,  a ! 
dilute  acid  in  which  are  dissolved  the  soluble  aromatic  parts  of  cinna-  j; 
mon  and  ginger,  also  contains  nearly  I3J  (13.36)  per  cent,  of  acid  1 
(II2SO4).  There  are  some  definite  compounds  of  sulphuric  acid  with  || 
water  ; the  first  (H2SO4, 11., 0)  may  be  obtained  in  crystals.  ij 

Sulphuric  anhydride  (SO2)  is  a wdiite  silky  crystalline  solid, 
having  no  acid  properties.  It  is  made  by  distilling  sulphuric  acid 
Avith  phosphoric  anhydride  (311.2804+ P2O5  =2Il3P04+ 3SO3).  I 
appears  to  unite  with  sulphuric  acid  and  some  other  normal  sul-  ) 
phates  to  form  compounds  (R'2S04,  SO3)  resembling  in  constitution  i 


SULPHATES. 


277 


red  chromate  of  potassium  or  borax.  The  fuming  sulphuric  acid 
SO3),  made  at  Nordhausen  in  Saxony,  seems  to  be  such  a 

body. 

Note. — Sulphuric  acid  is  a most  valuable  compound  to  all  chemists 
and  manufacturers  of  chemical  substances.  It  is  the  key  by  which 
hundreds  of  chemical  salts  are  unlocked,  and  their  contents  utilized. 
To  describe  its  uses  would  be  to  write  a work  on  chemistry. 

Analytical  Reactions  (Tests). 

Fii^st  Analytical  Reaction. — To  solution  of  a sulphate 
add  solution  of  a barium  salt ; a white  precipitate  of  sul- 
phate of  barium  (BaSOJ  falls.  Add  nitric  acid  and  boil 
the  mixture,  the  precipitate  does  not  dissolve. 

This  reaction  is  as  highly  characteristic  of  sulphates  as  it  has  been 
stated  to  be  of  barium  salts  [vide  page  88).  The  only  error  likely 
to  be  made  in  its  application  is  that  of  overlooking  the  fact  that 
nitrate  and  chloride  of  barium  are  less  soluble  in  strong  acid  than  in 
water.  On  adding  the  barium  salt  to  the  acid  liquid,  therefore,  a 
white  precipitate  may  be  obtained,  which  is  simply  the  nitrate  or 
chloride  of  barium.  The  appearance  of  such  a precipitate  differs  con- 
siderably from  that  of  the  barium  sulphate  ; hence  a careful  operator 
will  not  be  misled.  Should  any  doubt  remain,  water  should  be  added, 
which  will  dissolve  the  nitrate  or  chloride,  but  not  affect  the  sulphate. 

Second  Analytical  Reaction. — Mix  a fragment  of  an  in- 
soluble sulphate  (BaSO^  e.  g.)  with  carbonate  of  potassium 
or  of  sodium ; or,  better,  with  both  carbonates,  and  fuse 
the  mixture  in  a small  crucible.  Digest  the  residue  when 
cold,  in  water,  and  filter ; the  filtrate  may  be  tested  for  the 
sulphuric  radical. 

This  is  a convenient  method  of  qualitatively  analyzing  insoluble 
sulphates,  such  as  those  of  barium  and  lead. 

Third  Analytical  Reaction. — Mix  a fragment  of  an  in- 
soluble sulphate  with  a little  alkaline  carbonate  on  a piece 
of  charcoal,  taking  care  that  some  of  the  charcoal-dust  is 
included  in  the  mixture.  Heat  the  little  heap  in  the  blow- 
pipe*flame  until  it  fuses,  and,  when  cold,  add  a drop  of 
acid ; sulphuretted  hydrogen  is  evolved,  recognized  by  its 
odor. 

This  is  another  process  for  the  recognition  of  insoluble  sulphates. 
Other  preparations  of  sulphur,  and  sulphur  itself,  give  a similar  re- 
sult. It  is  therefore  rather  a test  for  sulphur  and  its  compounds  than 
sulphates  only  ; but  the  absence  of  other  salts  can  generally,  if  neces- 
sary, be  previously  determined. 

24 


278 


SALTS  OF  ACIDULOUS  RA^DICALS. 


Note. — The  presence  of  the  sulphuric  radical  in  a solution  having 
been  proved  by  the  above  reactions,  its  occurrence  as  the  normal  sul- 
phate of  a metal  is  demonstrated  by  the  neutral,  or  nearly  neutral, 
deportment  of  the  liquid  with  test-paper,  and  the  detection  of  the 
metal — its  occurrence  as  sulphuric  acid  or  an  acid  sulphate  by  the 
sourness  of  the  liquid  to  the  taste,  and  the  effervescence  produced  on 
the  addition  of  a carbonate. 

Antidote. — In  cases  of  poisoning  by  strong  sulphuric  acid,  solution 
of  carbonate  of  sodium  (common  washing-soda),  magnesia  and  water, 
etc.,  may  be  administered  as  antidotes. 


QUESTIONS  AND  EXEECISES. 

513.  What  is  the  formula  of  sulphuric  acid,  and  what  its  molecular 
weight  ? 

514.  How  is  it  related  to  other  sulphates  ? 

515.  Write  a short  article  on  the  manufacture  ’ of  sulphuric  acid, 
giving  diagrams. 

516.  How  may  nitrous  compounds  be  detected  in,  and  eliminated 
from,  sulphuric  acid  ? 

517.  State  the  method  by  which  the  presence  of  arsenic  is  detected 
in  sulphuric  acid,  and  explain  the  process  by  which  it  may  be  re- 
moved. 

518.  Define  sulphates,  acid  sulphates,  and  double  sulphates. 

519.  What  percentage  of  real  acid  is  contained  in  commercial  oil 
of  vitriol? 

520.  State  the  strength  of  the  official  “diluted”  and  “aromatic” 
sulphuric  acid. 

521.  By  what  process  is  sulphuric  anhydride  obtained  from  Nord- 
hausen  sulphuric  acid  ? 

522.  Explain  the  reactions  which  occur  in  testing  for  sulphates. 

523.  Ascertain  by  calculation  the  weight  of  oil  of  vitriol  (of  96.8 
per  cent.)  necessary  for  the  production  of  one  ton  of  dry  sulphate  of 
ammonium. — Ans.  1718  pounds. 

524.  Name  the  antidotes  in  cases  of  poisoning  by  strong  sulphuric 
acid. 


CARBONIC  ACID  AND  OTHER  CARBONATES. 

Formula  of  carbonic  acid  H.^CO.^.  Molecular  weight  62.  Formula  . 
of  carbonic  acid  gas,  or  carbonic  anhydride,  commonly  termed  car- 
bonic acid,  CO2. 

Sources. — Carbonates  (compounds  containing  the  grouping  CO3) 
are  very  common  in  nature,  the  calcium  carbonate  (CaCOg)  being 
widely  distributed  as  chalk,  limestone,  or  marble.  The  hydrogen 
carbonate,  true  carbonic  acid,  is  not  known,  unless,  indeed,  carbonic 
acid  gas  assumes  that  condition  on  dissolving  in  water  (Aqua  Acidi 
Carhonici,  U.  S.  P.).  Such  a solution  (see  page  71)  changes  the 


CARBONATES. 


2‘r9 


color  of  blue  litmus-paper,  and  the  gas  does  not ; this  may  be  because 
only  the  true  acid  (Pl.^COg)  affects  the  litmus,  or  because  the  gas 
(CO2)  cannot  come  into  real  contact  with  the  litmus  without  a me- 
dium. From  the  commonest  natural  carbonate,  carbonate  of  calcium, 
are  derived  the  carbonic  constituents  of  the  one  most  frequently  used 
in  medicine,  carbonate  of  sodium. 

Carbonate  of  sodium  is  prepared  from  the  chief  natural  salt,  the 
chloride.  After  the  chloride  has  been  converted  into  sulphate  (salt- 
cake)  by  sulphuric  acid, 

2NaCl  + H2SO,  = Na^SO,  + 2HC1, 

the  sulphate  is  roasted  with  limestone  and  small  coal,  by  which  car- 
bonate of  sodium  and  sulphide  of  calcium  are  formed  : — 

Na^SO,  + C,  + CaC03=  CaS  + Na^COg  + 4CO. 

Carbonic  oxide  gas  and  a little  carbonic  acid  gas  from  the  excess  of 
chalk  escape ; the  residual  mass  (black  ash)  is  digested  in  water,  in 
which  the  carbonate  of  sodium  dissolves,  the  sulphide  of  calcium  with 
a little  oxide  remaining  insoluble.  The  solution  is  evaporated  to 
dryness,  and  yields  crude  carbonate  of  sodium.  This  is  roasted  with 
a small  quantity  of  sawdust,  to  convert  any  caustic  soda  resulting 
from  the  action  of  the  lime  on  the  carbonate,  into  normal  carbonate. 
The  product  is  soda-ash.  Dissolved  in  water  and  crystallized,  it 
constitutes  the  ordinary  “ soda”  used  for  washing  purposes : recrys- 
tallized and  sometimes  ground,  it  forms  the  official  carbonate  of 
sodium  {Sodii  Carbonas,  U.  S.  P.)  (Na.^COg,  lOH^O).  The  reac- 
tion is  rendered  more  intelligible  by  regarding  it  as  occurring  in  two 
stages : 1st,  the  reduction  of  the  sulphate  of  sodium  to  sulphide  by 
the  carbon  of  the  coal, 

Na^SO,  + 0,  = Na^S  + 4C0  ; 

2d,  the  reaction  of  the  sulphide  of  sodium  and  carbonate  of  calcium, 
giving  soluble  carbonate  of  sodium,  thus — 

Na^S  + CaCO.,  = Na^COg  + CaS. 

The  sulphur  in  the  residual  sulphide  of  calcium  may  be  recovered 
by  exposure  to  air,  and  the  subsequent  action  of  hydrochloric  acid. 
Some  hyposulphite  of 'calcium  (CaS203)  is  first  formed  and  the  action 
of  the  acid  on  this  and  undecomposed  sulphide  gives  chloride  of  cal- 
cium, water,  and  sulphur. 

Carbonic  acid  gas  (CO2)  is  a product  of  the  combustion  of  all 
carbonaceous  matters.  It  is  constantly  exhaled  by  animals  and 
inhaled  by  plants,  its  intermediate  storehouse  being  the  atmosphere, 
throughout  which  it  is  equally  distributed  by  diffusion  [vide  p.  22) 
to  the  extent  of  about  4 parts  in  10,000.  A larger  proportion  than 
that  just  mentioned  gives  to  confined  air  depressing  effects,  4 or  5 
per  cent,  rendering  the  atmosphere  poisonous  when  taken  into  the 
blood  from  the  lungs.  Carbonic  acid,  however,  may  be  taken  into 
the  stomach  with  beneficial  sedative  effects ; hence,  probably,  much 
of  the  value  of  such  effervescing  liquids  as.  soda-water,  lemonade, 
and  solutions  of  the  various  granulated  preparations  and  effervescing 


280 


SALTS  OF  ACIDULOUS  RADICALS. 


powders  {vide  p.  73).  The  gas  liquefies  on  being  compressed,  and  the 
liquid  solidifies  on  being  cooled.  Carbonic  acid  gas  is  twenty-two 
times  as  heavy  as  hydrogen,  and  about  half  as  heavy  again  as  air. 

Reactions. 

Synthetical  and  Analytical  Reactions, — 1.  To  a fragment 
of  marble  in  a test-tube  add  water  and  then  hydrochloric 
acid  ; carbonic  acid  gas  (COJ  is  evolved,  and  may  be  con- 
veyed into  water  or  solutions  of  salts  by  the  usual  delivery- 
tube. 

This  is  the  process  of  the  British  Pharmacopoeia,  and  the  one 
usually  adopted  for  experimental  purposes.  Passed  into  carbonate 
of  sodium,  the  gas  gives  Sodii  Bicarbonas  (p.  69),  and  into  carbonate 
of  potassium,  Potassii  Bicarbonas  (p.  58).  On  the  large  scale  the 
gas  is  prepared  from  chalk  or  marble  and  sulphuric  acid,  frequent 
stirring  promoting  its  escape. 

2.  Pass  the  gas  into  lime-water;  a wdiite  precipitate  of 
carbonate  of  calcium  (CaCOg)  falls.  Solution  of  subacetate 
of  lead  may  be  used  instead  of,  and  is  perhaps  even  a more 
delicate  test  than,  lime-water. 

The  evolution  of  a gas  on  adding  an  acid  to  a salt,  warming  the 
mixture  if  necessary,  the  gas  being  inodorous  and  giving  a wdiite 
precipitate  with  lime-water,  is  sufficient  evidence  of  the  presence  of 
a carbonate.  Carbonates  in  solution  of  ammonia,  potash,  or  soda, 
may  be  detected  by  the  direct  addition  of  solution  of  lime. 

3.  Blow  air  from  the  lungs  through  a glass  tube  into 
lime-water;  the  presence  of  carbonic  acid  gas  is  at  once 
indicated. 

The  passage  of  a considerable  quantity  of  normal  air  through 
lime-water  produces  a similar  effect.  A bottle  containing  lime-water 
soon  becomes  coated  with  carbonate  of  calcium  from  absorption  of 
carbonic  acid  gas. 

4.  Fill  a dry  test-tube  with  the  gas,  by  passing  the 
delivery-tube  of  the  above  apparatus  to  the  bottom  of  the 
test-tube.  Being  rather  more  than  once  and  a half  as 
heavy  as  the  air  (1.529),  it  will  displace  the  latter.  Prove 
the  presence  of  the  gas  by  pouring  it  slowly,  as  if  a visible 
liquid,  into  another  test-tube  containing  lime-water;  the 
characteristic  cloudiness  and  precipitate  are  obtained  on 
gently  shaking  the  lime-water. 

In  testing  for  carbonates  by  bringing  evolved  gas  into  contact  with 
lime-water,  the  preparation  and  adaptation  of  a delivery-tube  may 
often  be  avoided  by  pouring  the  gas  from  the  generating-tube  into 
that  containing  the  lime-water  in  the  manner  just  indicated. 


CARBONATES. 


281 


5.  Pass  carbonic  acid  ^as  through  lime-water  until  the 
precipitate  at  first  formed  is  dissolved.  The  resulting 
liquid  is  a solution  of  carbonate  of  calcium  in  carbonic 
acid  water.  Boil  the  solution  ; carbonic  acid  gas  escapes, 
and  the  carbonate  is  again  precipitated. 

This  experiment  will  serve  to  show  how  chalk  is  kept  in  solution 
in  ordinary  well-waters,  giving  the  property  of  ‘‘  hardness,”  and  how 
the/wr  or  stone-like  deposit  in  tea-kettles  and  boilers  is  formed.  It 
should  be  here  stated  that  sulphate  of  calcium  produces  similar  hard- 
ness, and  that  these,  with  small  quantities  of  the  sulphate  and  car- 
bonate of  magnesium,  constitute  the  hardening  constituents  of  w^ell- 
waters,  a curd  (oleate  of  calcium  or  magnesium)  being  formed  when- 
ever soap  is  used  with  such  waters.  An  enormous  amount  of  soap  is 
w^asted  through  the  employment  of  hard  water  for  washing-purposes. 
The  hardness  produced  by  the  earthy  carbonates  is  termed  “ tempo- 
rary hardness,”  because  removable  by  ebullition  ; that  by  the  earthy 
sulphates  ‘‘permanent  hardness”  because  unaffected  by  ebullition. 
The  addition  of  lime-water  or  a mixture  of  lime  and  water  removes 
temporary  hardness  (reac.  2,  page  280),  and  carbonate  of  sodium, 
“ washing  soda,”  both  temporary  and  permanent  hardness,  in  the 
latter  case  sulphate  of  sodium  remaining  in  solution.  Carbonate  of 
barium  (ground  witherite)  also  decomposes  sulphates  of  calcium  and 
magnesium,  sulphate  of  barium  being  precipitated  and  carbonates 
of  calcium  or  magnesium  formed ; the  latter  and  the  carbonates 
originally  in  the  water  may  then  be  precipitated  by  ebullition  or  by 
the  action  of  lime-water.  But  the  injurious  effects  of  barium  salts 
on  man  and  the  lower  animals  prevents  the  carbonate  being  used  for 
purifying  water  for  drinking  purposes,  as  by  accident  or  an  unfore- 
seen reaction  a portion  might  become  dissolved. 


QUESTIONS  AND  EXERCISES. 

525.  Name  the  chief  natural  carbonates. 

526.  What  are  the  formulae  of  carbonic  acid  and  carbonic  acid 
gas? 

527.  Adduce  evidence  of  the  existence  of  true  carbonic  acid. 
Trace  the  steps  by  which  the  carbonic  constituents  of  chalk 

are^Klgs^ryed  to  sodium  by  the  process  usually  adopted  in  alkali- 
works— the^anufacture  of  “ soda.” 

529.  Carbonic  acid  gas  is  constantly  exhaled  from  the  lungs  of 
animals ; why  does  it  not  accumulate  in  the  atmosphere  ? 

530.  What  is  the  effect  of  pressure  on  carbonic  acid  gas  ? 

531.  State  the  specific  gravity  of  carbonic  acid  gas. 

532.  By  what  processes  may  carbonic  acid  gas  be  obtained  for  ex- 
perimental and  manufacturing-purposes  ? 

533.  Describe  the  action  of  carbonic  acid  gas  on  the  carbonates  of 
potassium  or  sodium. 

534.  How  may  carbonic  acid  be  detected  in  expired  air  ? 

24* 


282  SALTS  OF  ACIDULOUS  RADICALS. 

535.  To  what  extent  is  carbonic  acid  gas  heavier  than  air  ? 

536.  What  quantity  of  chalk  (90  per  cent,  pure)  will  be  required 
to  furnish  the  carbonic  acid  ^necessary  to  convert  one  ton  .of  car- 
bonate of  potassium  (containing  83  per  cent,  of  K2CO3)  into  acid 
carbonate,  supposing  no  gas  to  be  wasted  ? — Ans.  1500  lbs. 

537.  Define  “ hardness”  in  water. 

538.  How  may  the  presence  of  carbonates  be  demonstrated  ? 


OXALIC  ACID  AND  OTHER  OXALATES. 

Formula  of  Oxalic  Acid  2H2O.  Molecular  weight  126. 

Sources. — Oxalates  occur  in  nature  in  the  juices  of  some  plants, 
as  wood-sorrel,  rhubard,  the  common  dock,  and  certain  lichens ; but 
the  hydrogen  oxalate  (oxalic  acid)  and  other  oxalates  are  all  made 
artificially.  Many  organic  substances  yield  oxalic  acid  w^hen  boiled 
with  nitric  acid,  and  an  alkaline  oxalate  when  roasted  with  a mixture 
of  the  hydrates  of  potassium  and  sodium. 

Experimental  Process. — On  the  small  scale,  a mixture  of  nitric 
acid  and  loaf  sugar  yields  the  acid  in  the  purest  form,  the  two  being 
boiled  together  for  some  time. 

Manufacturing  Process. — On  the  large  scale,  sawdust  is  roasted 
with  alkalies,  resulting  oxalate  of  sodium  decomposed  by  lime  with 
formation  of  oxalate  of  calcium,  the  latter  digested  with  sulphuric 
acid,  and  the  liberated  oxalic  acid  (Oxalic  Acid  of  Commerce,  B.  P.) 
purified  by  recrystallization  (Oxalic  Acid,  Purified,  B.  P.,  Acidum 
Oxalicum,  U.  S.  P.).  ^ 

Quantivalence. — The  elements  represented  by  the  formula  CaO^ 
are  those  characteristic  of  oxalates.  They  form  a bivalent  group- 
ing; hence  normal  oxalates  (R'2C204),  and  acid  oxalates  (R'HC20J 
exist. 

Salt  of  sorrel  is  a crystalline  compound  of  oxalic  acid  with  acid 
potassium  oxalate,  the  crystals  containing  two  molecules  of  water  of 
crystallization  (KHC2O4,  H2C2O4,  2FI2O). 

Oxalate  of  iron  [Ferri  Oxalas,  U.  S.  P.)  is  a crystalline  powder 
made  by  precipitating  a solution  of  sulphate  of  iron  with  oxalic  acid. 
When  heated  in  contact  with  air  it  decomposes  with  a faint  combus- 
tion, and  leaves  a residue  of  not  less  than  forty-eight  per  cent,  of  red 
oxide  of  iron. 


Ayialytical  Reactions  {Tests). 

First  Analytical  Reaction. — To  solution  of  an  oxalate 
(oxalate  of  ammonium  e.  g.)  add  solution  of  chloride  of 
calcium  ; a white  precipitate  falls.  Add  to  the  precipitate 
excess  of  acetic  acid ; it  is  insoluble.  Add  hydrochloric 
acid  ; the  precipitate  is  dissolved. 

The  formation  of  a w^hite  precipitate  on  adding  a calcium  or  barium 
salt,  insoluble  in  acetic  but  soluble  in  hjnlroQhloric  or  nitric  acid,  is 


OXALATES. 


283 


usually  sufficient  proof  of  the  presence  of  an  oxalate.  The  action 
of  the  liquid  on  litmus  paper,  effervescence  with  carbonate  of  sodium, 
and  absence  of  metals,  would  indicate  that  the  oxalate  is  that  of 
hydrogen,  oxalic  acid. 

Antidote. — In  cases  of  poisoning  by  oxalic  acid  or  salt  of  sorrel, 
chalk  and  water  may  be  administered  as  a chemical  antidote  (with 
the  view  of  producing  the  insoluble  oxalate  of  calcium),  emetics  and 
the  stomach-pump  being  used  as  soon  as  possible. 

Second  Analytical  Reaction. — Heat  a fragment  of  a fixed 
metallic  oxalate  (an  oxalate  of  potassium  for  example)  in 
a test-tube  ; decomposition  occurs,  carbonic  oxide  (CO) 
(a  gas  that  will  be  noticed  subsequently)  is  liberated,  and 
a carbonate  of  the  metal  remains.  Add  water  and  then 
an  acid  to  the  residue  ; effervescence  occurs. 

This  is  a ready  test  for  insoluble  oxalates,  and  is  trustworthy  if, 
on  heating  the  substance,  no  charring  occurs.  Organic  salts  of 
metals  decompose  when  heated,  and  leave  a residue  of  carbonate,  but 
except  in  the  case  of  oxalate,  the  residue  is  always  accompanied  by 
much  charcoal. 

Other  Analytical  Reactions. — Nitrate  of  silver  gives, 

with  oxalates,  white  oxalate  of  silver  (Ag2C20J. Dry 

oxalates  are  decomposed  w^hen  heated  with  strong  sul- 
phuric acid,  carbonic  oxide  and  carbonic  acid  gases  escap- 
ing. If  much  of  the  substance  be  operated  on,  the  gas 
may  be  crashed  with  an  alkali,  the  carbonic  acid  be  thus 
removed,  and  the  carbonic  oxide  be  ignited  ; it  will  be 
found  to  burn  with  a characteristic  bluish  flame. Oxa- 

lates, when  mixed  with  water,  black  oxide  of  manganese 
(free  from  carbonates),  and  sulphuric  acid,  3deld  carbonic 
acid  gas,  which  may  be  tested  by  lime-water  in  the  usual 

manner. Insoluble  oxalates,  such  as  those  of  calcium 

and  magnesium,  may  be  decomposed  hy  ebullition  with 
solution  of  carbonate  of  sodium  ; after  filtration  the  oxalic 
radical  will  be  found  in  the  clear  liquid  as  soluble  oxalate 
of  sodium. 

Test  of  Purity. — “ Purified  oxalic  acid  ....  is  entirely  dissi- 
pated by  a heat  below  350^  F.”  (B.  P.) 


QUESTIONS  AND  EXERCISES. 

539.  Explain  the  constitution  of  oxalates. 

540.  State  how  oxalates  are  obtained. 

541.  What  is  the  quantivalence  of  the  oxalic  radical  ? 

542.  Give  the  formula  of  “ salt  of  sorrel.” 


284 


SALTS  OF  ACIDULOUS  RADICALS. 


543.  Mention  the  chief  test  for  oxalic  acid  and  other  soluble  oxa- 
lates. 

544.  Name  the  antidote  for  oxalic  acid,  and  describe  its  action. 

545.  By  what  reactions  are  insoluble  oxalates  recognized  ? 


TARTARIC  ACID  AND  OTHER  TARTRATES. 

Formula  of  Tartaric  Acid  H2C4H^Og,  or  H2T. 

Molecular  weight  150. 

Sources. — Tartrates  exist  in  the  juice  of  many  fruits ; but  it  is 
from  that  of  the  grape  that  our  supplies  are  usually  obtained. 
Grape-juice  contains  much  acid  tartrate  of  potassium,  which  is  gradu- 
ally deposited  when  the  juice  is  fermented,  as  in  making  wine ; for 
acid  tartrate  of  potassium,  not  very  soluble  in  aqueous  liquids,  is 
still  less  so  in  spirituous,  and  hence  crystallizes  out  as  the  sugar  of 
the  grape-juice  is  gradually  converted  into  alcohol.  It  is  found  with 
tartrate  of  calcium  lining  the  vessels  in  which  wine  is  kept ; and  it  is 
from  this  crude  tartar*  (argal  or  argol),  as  well  as  from  what  tartar 
may  be  remaining  in  the  marc  left  after  the  juice  has  been  pressed 
from  the  grapes,  that  tartaric  acid  and  other  tartrates  are  prepared. 

Cream  of  Tartar,  purified  by  crystallization  [Potassce  Tartras 
Adda,  B.  P.,  Potassii  Bitaftras,  U.  S.  P.),  occurs  as  a “gritty 
white  powder,  or  fragments  of  cakes  crystallized  on  one  surface of 
a pleasant  acid  taste,  soluble  in  180  parts  of  cold  and  6 of  boiling 
water,  insoluble  in  spirit. 

Quantivalence. — The  elements  represented  by  the  formula  C^H^Og 
are  those  characteristic  of  tartrates.  They  form  a bivalent  grouping  ; 
hence  normal  tartrates  tartrates  (R'HT)  exist. 

Tartrate  of  potassium,  the  Potassii  Tartras  of  the  U.  S.  Pharma- 
copoeia (K2C4H40g)  and  Rochelle  Salt,  or  tartrate  of  potassium  and 
sodium  (KNa04H40g,  4H2O);  the  official  Potassii  et  Sodii  Tartras 
(Soda  Tartarata,  B.  P.),  are  illustrations  of  normal  tartrates,  while 
Cream  of  Tartar  is  an  example  of  acid  tartrates.  The  only  official 
tartrate  not  apparently  included  in  these  general  formulae  is  tartar- 
emetic  (Antimonium  Tartaratum,  B.  P.,  Antimonii  et  Potassii 
Tartras,  U.  S.  P.),  which  is  sometimes  regarded  as  the  double  tar- 
trate of  potassium  and  a hypothetical  radical,  antimonyl  (SbO),  thus, 
KSb0C4H40g.  Possibly,  however,  it  is  but  an  oxytartrate  of  anti- 
mony (Sb202T)  with  normal  tartrate  of  potassium  (KjT) ; for  there 
are  several  oxycompoundsof  antimony  analogous  to  the  oxycompounds 

* “It  is  called  tartar^  says  Paracelsus,  “because  it  produces  oil, 
water,  tincture,  and  salt,  which  burn  the  patient  as  tartarus  does.” 
Tartarus  is  Latin  (Taprapof  Tartaros,  Greek)  for  hetl.  The  products  of 
its  destructive  distillation  are  certainly  somewhat  irritating  in  taste 
and  smell  ; and  the  “ salt”  (carbonate  of  potassium)  that  is  left  is 
diuretic,  and,  in  larger  quantities,  powerfully  corrosive. 

A boiling  solution  of  tartar  yields  a floating  crust  of  minute  cry.stals 
on  cooling,  hence  the  term  cream  of  tartar. 


TARTRATES. 


285 


of  bismuth  that  have  been  described  (p.  225),  normal  salts  partially 
decomposed  by  water  into  oxides,  and  many  of  these  oxycompounds 
readily  unite  with  normal  salts  of  other  basylous  radicals.  Tartar 
emetic  would  thus  be  oxytartrate  of  antimony  with  tartrate  of  potas- 
sium (Sb202T,  K2T,  or  Sb202C4H406,  K20^H^Og). 


Tartaric  Acid. 


Tartaric  Acid  [Acidum  Tartaricum,  B.  P.  and  U.  S.  P.)  is 
obtained,  according  to  the  British  Pharmacopoeia,  by  boiling  cream 
of  tartar  [Potassce  Tartras  Adda,  B.  P.,  Pbtassii  Bitartras,  U.  S. 
P.)  with  water,  adding  chalk  till  effervescence  ceases,  and  then  chlo- 
ride of  calcium  so  long  as  a precipitate  falls ; the  two  portions  of  tar- 
trate of  calcium  thus  consecutively  formed  are  thoroughly  washed, 
treated  with  sulphuric  acid,  the  mixture  boiled  for  a short  time,  re- 
sulting sulphate  of  calcium  mostly  separated  by  filtration,  the  filtrate 
concentrated  by  evaporation,  any  sulphate  of  calcium  that  may  have 
deposited  removed  as  before,  and  concentration  continued  until  the 
solution  is  strong  enough  to  crystallize.  Tartrate  of  calcium  from 
9 ounces  of  cream  of  tartar  requires  5 ounces  by  weight  of  sulphuric 
acid  for  complete  decomposition. 


2KHT  + CaCOg  = CaT  + K2T  + H^O  + OO2 

Acid  tartrate  Carbonate  of  Tartrate  of  Tartrate  of  Water.  Carbonic 
of  potassium.  calcium.  calcium.  potassium.  acid  gas. 


K2T  + CaCl2 

Tartrate  of  Chloride  of 
potassium.  calcium. 


CaT  + 2KC1 

Tartrate  of  Chloride  of 
calcium.  potassium. 


2CaT  + 2H2SO, 

Tartrate  of  Sulphuric 

calcium.  acid. 


20aS0,  4-  2H2T 

Sulphate  of  Tartaric 

calcium.  acid. 


Tartaric  acid  occurs  in  colorless  crystals,  or  the  same  powdered. 
It  is  strongly  acid  and  readily  soluble  in  water  or  spirit.  One  part 
in  8 of  water  and  2 of  spirit  of  wine  forms  “ Solution  of  Tartaric  Acid,” 
B.  P.  Its  aqueous  solution  is  not  stable. 

Parcels  of  tartaric  acid  often  contain  crystals  of  an  allotropic  or 
physically  isomeric  modification  [vide  “ Allotropy”  and  “ Isomerism” 
in  Index).  It  is  termed  Paratartaric  acid  (rtapa,  para,  beside)  or 
Racemic  acid  (racemus,  a bunch  of  grapes),  and  is  a combination  of 
ordinary  tartaric  acid,  whose  solution  twists  a ray  of  polarized  light 
to  the  right  hand  (dextrotartaric  or  dextroracemic  acid)  and  of  laevo- 
tartaric  or  laGvoracemic  acid,  whose  solution  twists  a polarized  ray  to 
the  left.  Racemic  acid  is  inactive  in  this  respect,  the  opposite  pro- 
perties of  its  constituents  neutralizing  each  other.  Racemic  acid  is 
less  soluble  in  alcohol  than  tartaric  acid. 


Reactions. 

Tartrate  of  Potassium. 

Synthetical  Reactions, — To  a small  quantity  of  a strong 
solution  of  carbonate  of  potassium  add  acid  tartrate  of 
potassium  so  long  as  effervescence  occurs ; the  resulting 


236 


SALTS  OF  ACIDULOUS  RADICALS. 


liquid  is  solution  of  normal  tartrate  of  potassium  {Potassii 
Tarlras^  U.  S.  P.)  (K/f),  crystals  of  which  may  be  obtained 
on  evaporation. 

Note. — This  is  a common  method  of  converting  an  acid  salt  of  a 
bivalent  acidulous  radical  into  a normal  salt.  The  carbonate  added 
need  not  be  a carbonate  of  the  same,  but  ma}^  be  of  a different 
metal;  compounds  like  Rochelle  salt  (KNaT)  are  then  obtained. 
Thus : — 


Tartrate  of  Potassium  and  Sodium. 

To  a strong  hot  solution  of  carbonate  of  sodium  add 
acid  tartrate  of  potassium  until  effervescence  ceases ; the 
resulting  liquid  is  solution  of  tartrate  of  potassium  and 
sodium;  on  cooling,  it  yields  cr3^stals.  This  is  the  official 
process  {Soda  Tartar ata^  B.  P.,  Fotassii  et  Sodii  Tartras^  ; 
U.  S.  P.)  (KNaC,H,0„4H,0).  | 

Nsi.CO,  + 2KHC,H,Oe  = 2KNaC,n,Og  + H^O  + CO^ 

Carbonate  Acid  tartrate  Tartrate  of  potas-  Water.  Carbonic 

of  sodium.  of  potassium.  sium  and  sodium,  acid  gas. 

Crystals  of  Rochelle  salt  are  usually  halves  of  colorless,  trans- 
parent, right  rhombic  prisms,  slightly  efflorescent  in  dry  air,  soluble 
in  five  parts  of  boiling  water.  Tartrate  of  potassium  is  slightly 
deliquescent,  soluble  in  about  four  parts  of  boiling  water. 

Equivalent  Weights  of  Tartaric  Acid,  Carbonate  of  Potassium, 
Bicarbonate  of  Potassium,  Carbonate  of  Sodium,  Bicarbonate 
of  Sodium,  and  Carbonates  of  Ammonium  and  Magnesium  ; 
repeated  for  2Q  parts  of  each  (and,  incidentally,  for  other  propor- 
tions.) 


Ta rt,.  Acid 

H3C4H4O6 — 150 

20 

18i! 

|l5 

lOi 

175 

25i 

3I5 

Carb.  Potas 

K3CO3  (of  8t  per  cent.). . . = 164 

22 

20 

16i 

lU 

19i 

28 

3U 

T?ica,rb.  Pot,  .... 

2(KHC03) — 200 

9R4 

24i 

20 

14 

235 

34 

42 

Carb  Soda  (cryst.) 

Na,CO3,10HaO — 286 

T 

38 

34f 

28h 

20 

34 

48i 

60 

Ricarb  Sod  

2(NaHC03) — 168 

225 

20i 

16| 

115 

20 

28.} 

351 

Carb.  Ammon.... 

(N4H,,C303)--2 =118 

15J 

Hi 

m 

8i 

14 

20 

245 

Carb.  Magnes 

(MgC03)3Mg2H0,4Ha0....  =95.5 

12i 

m 

95 

65 

ni 

16 

20 

Thus  20  parts  (grains  or  other  weights)  of  tartaric  acid  neutralize 
22  of  carbonate  of  potassium,  26|  of  bicarbonate  of  potassium,  38 
of  carbonate  of  sodium,  22^  of  bicarbonate  of  sodium,  15J  of  car- 
bonate of  ammonium,  or  12|  of  carbonate  of  magnesium.  Other 
quantities  of  tartaric  acid  (18^,  15,  10^,  17J,  25^,  31^)  saturate  the 
amounts  of  salts  mentioned  in  the  other  columns  and  vice  versa. 
A similar  Table  for  Citric  Acid  will  be  found  at  page  290,  and  for 
both  acids  in  the  Appendix.  These  Tables  afford  good  illustrations 


TARTRATES. 


28T 


of  the  laws  of  chemical  combination  (page  40).  The  reader  should 
verify  a few  of  the  numbers  by  calculation  from  the  atomic  weights 
of  the  elements  concerned  in  the  reactions,  remembering  that  the 
salts  formed  are  considered  to  be  neutral  in  constitution.  In  medical 
practice  effervescing  saline  draughts  are  often  designedly  prescribed 
to  contain  an  amount  of  acid  or  alkali  considerably  in  excess  of  the 
proportions  required  for  perfect  neutrality. 

A common  form  of  Seidlitz  Powder  consists  of  3 parts  of  Rochelle 
salt  (120  grains)  with  1 (40  grains)  of  acid  carbonate  of  sodium  (the 
mixture  usually  wrapped  in  blue  paper),  and  1 (40  grains)  of  tartaric 
acid  (wrapped  in  white  paper).  When  administered,  the  latter  is 
dissolved  in  a tumbler  rather  more  than  half  full  of  water,  the  former 
added,  and  the  mixture  drunk  during  effervescence.  It  will  be  seen 
that  the  salts  swallowed  are  tartrate  of  potassium  and  sodium 
(KNaT^IH^O),  tartrate  of  sodium  (Na2T,2H20),  and  acid  tartrate  of 
sodium  or  potassium.  The  last-mentioned  salt  results  because  11^ 
per  cent.  (4^  grains)  of  the  tartaric  acid  is  in  excess  of  the  quantity 
necessary  for  the  formation  of  neutral  tartrate  of  sodium.  This 
amount  of  acid  salt  gives  agreeable  acidity  to  the  draught.  The 
United  States  formula  (Palveres  Effervescentes  Aperientes,  U.  S.  P.) 
includes  rather  less  tartaric  acid,  so  that  only  neutral  salts  are 
formed. 


Analytical  Reactions  (Tests), 

Fii'st  Analytical  Reaction, — To  solution  of  any  normal 
tartrate,  or  tartaric  acid  made  neutral  by  solution  of  soda, 
add  solution  of  chloride  of  calcium;  a white  precipitate, 
[tartrate  of  calcium,  falls.  Collect  the  precipitate  on  a 
filter,  wash,  place  a small  quantit}^  in  a test-tube,  and  add 
I solution  of  potash;  on  stirring  the  mixture  the  precipitate 
dissolves.  Heat  the  solution;  the  tartrate  of  calcium  is 
again  precipitated. 

The  solubility  of  tartrate  of  calcium  in  cold  potash  solution  enables 
the  analyst  to  distinguish  between  tartrates  and  citrates,  otherwise 
a difficult  matter.  Citrate  of  calcium  is  not  soluble  in  the  alkali. 
[The  absence  of  much  ammonical  salt  must  be  insured  in  both  cases, 
.the  precipitates  being  soluble  in  such  liquids. 

I Second  Analytical  Reaction. — Acidulate  a solution  of  a 
[tartrate  with  acetic  acid,  add  acetate  of  potassium,  and 
[well  stir  the  mixture;  a crystalline  precipitate  of  acid  tar- 
itrate  of  potassium  slowly  separates.  Tlie  precipitate  being 
insoluble  in  alcohol,  the  addition  of  a little  spirit  of  wine 
renders  the  test  more  delicate. 

This  reaction  is  not  applicable  in  testing  for  very  small  quantities 
of  tartrates,  the  acid  tartrate  of  potassium  being  not  altogether 
insoluble. 


288 


SALTS  OF  ACIDULOUS  RADICALS. 


Third  Analytical  Reaction. — To  a neutral  solution  of  a 
tartrate  add  solution  of  nitrate  of  silver ; a white  precipi-, 
tate  of  tartrate  of  silver,  Ag.^C4H^Og,  falls.  Boil  the  mix- 
ture ; it  blackens,  owing  to  the  reduction  of  the  salt  to 
metallic  silver. 

Other  Reactions. — Tartrates  heated  with  strong  sulphu- 
ric acid  char  immediately. Tartaric  acid  and  the  soluble 

tartrates  prevent  the  precipitation  of  ferric  and  other  hy- 
drates by  alkalies,  soluble  double  tartrates  being  formed 
(which  on  evaporation  yield  liquids  that  do  not  crystallize, 
but,  spread  on  sheets  of  glass,  dry  up  to  thin  transparent 
plates  or  scales).  The  ferri  et  potassii  tartras,  U.  S.  P. 
{Ferruni  Tartaratum.^  B.  P.),is  a preparation  of  this  kind. 

Tartrates  decompose  when  heated,  carbonates  being 

formed  and  carbon  set  free,  the  gaseous  products  having  a 
peculiar,  more  or  less  characteristic  smell,  resembling  that 
of  burnt  sugar. 


QUESTIONS  AND  EXERCISES. 

546.  State  the  origin  of  tartaric  acid  and  other  tartrates,  and  ex- 
plain the  deposition  of  argol,  crude  acid  tartrate  of  potassium,  during 
the  manufacture  of  wine. 

547.  What  are  the  chemical  formula  and  characters  of  “ cream  of 
tartar  ?” 

548.  Mention  the  formula  and  quantivalence  of  the  tartaric 
radical. 

549.  Write  formulae  of  normal,  acid,  and  double  tartrates,  tartar- 
emetic  being  treated  as  an  oxytartrate  of  antimony  with  tartrate  of, 
potassium. 

550.  Give  equations  or  diagrams  illustrative  of  the  production  ofl 
tartaric  acid  from  cream  of  tartar. 

551.  By  what  general  process  may  normal  or  double  tartrates  be 
obtained  from  acid  tartrate  of  potassium  ? 

552.  Work  out  sums  proving  the  correctness  of  some  of  the  figures! 

given  on  p.  286  as  showing  the  saturating  power  of  tartaric  acid  for 
various  quantities  of  different  carbonates,  and  give  diagrams  or  equa-: 
tions  of  the  reactions.  f 

553.  State  the  names  and  quantities  of  the  salts  resulting  from  the! 

admixture  of  120  grains  of  tartrate  of  potassium  and  sodium,  40 
grains  of  acid  carbonate  of  sodium,  and  40  grains  of  tartaric  acid, 
(^Seidlitz  powder).  j 

554.  Enumerate  the  tests  for  tartrates,  and  explain  the  effects  oil 

heat  on  tartrates  of  the  metals.  I 


I 


CITRATES. 


289 


CITRIC  ACID  AND  OTHER  CITRATES. 

Formula  of  Citric  Acid  HgCgH^O^,  H2O  or  HgCiAq. 

Molecular  weight  210. 

Source. — Citric  acid  [Acidum  Citricum,  B.  P.  and  U.  S.  P.)  ex- 
ists in  the  juice  of  many  of  our  common  garden  fruits;  thus  the  pulp 
of  the  fruit  of  Tamarindus  indica  ( Tamarindus,  B.  P.  and  U.  S. 
P.)  contains  nearly  10  per  cent,  (in  addition  to  1.5  of  tartaric  acid,  .5 
of  malic  acid,  and  3 per  cent,  of  acid  tartrate  of  potassium).  But  it 
is  from  the  lemon  or  lime  that  the  acid  of  commerce  is  usually  ob- 
tained. 

Process. — The  British  Pharmacopoeia  directs  that  the  hot  lemon- 
juice  (4  pints)  be  saturated  by  powdered  chalk  (4^  ounces),  the 
resulting  citrate  of  calcium  collected  on  a filter,  washed  with  hot 
water  till  the  liquor  passes  from  it  colorless  (by  which  not  only  the 
coloring  matter  but  the  mucilage,  sugar,  and  other  constituents  of 
the  juice  are  got  rid  of),  then  mixed  with  cold  water  (1  pint),  decom- 
posed by  sulphuric  acid  (2^  fluidounces  in  IJpint  of  water),  the  mix- 
ture boiled  for  half  an  hour,  filtered,  the  solution  evaporated  to  a 
density  of  1.21,  set  aside  for  24  hours,  then  poured  off  from  any  de- 
posit of  crystalline  sulphate  of  calcium,  further  concentrated,  and  set 
aside  to  crystallize. 

2H3CgH,0,  + SCaCOg  ==  Ca32CgH,07  + SH^O  + 3CO., 

Citric  acid  Carbonate  of  Citrate  of  Water.  Carbonic 

(impure).  calcium.  calcium.  acid  gas. 

02^,20,11,0,  + 3H,SO,  = + 30aS0, 

Citrate  of  Sulphuric  Citric  acid  Sulphate  of 

calcium.  acid.  (pure).  calcium. 

Quantivalence. — The  elements  represented  by  the  formula  CgHgO^ 
are  those  characteristic  of  citrates.  They  form  a trivalent  grouping  ; 
hence  three  classes  of  salts  may  exist — one,  two,  or  three  atoms  of 
the  basylous  hydrogen  in  the  acid,  HgCgH-O^,  being  displaced  by 
equivalent  proportions  of  other  basylous  radicals. 

Citric  acid  itself  is  the  only  citric  compound  of  much  direct  im- 
portance to  the  pharmacist.  It  usually  occurs  in  colorless  crystals 
soluble  in  half  their  weight  of  boiling  and  three-fourths  of  cold  water, 
less  soluble  in  spirit,  and  insoluble  in  ether.  A solution  of  about 
34  grains  in  1 ounce  of  water  forms  a sort  of  artificial  lemon-juice. 
Citrates  heated  with  strong  sulphuric  acid  to  about  212^  F.  evolve 
carbonic  oxide  gas,  and  at  higher  temperatures  acetone  and  carbonic 
acid  gas. 

Action  of  heat  on  citric  acid. — Citric  acid  slowly  heated  first 
loses  its  water  of  crystallization ; afterwards  (347'^  F.)  the  elements 
of  another  molecule  of  water  are  evolved  and  a residue  obtained 
from  which  ether  extracts  aconitic  acid  (HgCgHgOg),  identical  with 
the  aconitic  acid  (and  the  acid  first  termed  equisetic)  in  various 
species  of  A conitum  and  Equisetum. 

“ Effervescing  Citrate  of  Magnesia  f so-called,  is  generally  a 
mixture  of  bicarbonate  of  sodium,  citric  acid,  tartaric  acid,  sugar, 
either  carbonate  or  sulphate  of  magnesium  (sometimes  neither)  and 
25 


290 


SALTS  OF  ACIDULOUS  RADICALS. 


occasionally  essence  of  lemon.  True  citrate  of  magnesium  is  easily 
made  by  heating  together  calcined  magnesia  and  citric  acid ; it  is 
frequently  prescribed  in  France  in  doses  of  two  ounces.  Liquor 
Magnesii  Gitratis,  U.  S.  P.,  is  a bottled  mixture  of  magnesia,  citric 
acid,  and  syrup,  with  bicarbonate  of  potassium,  and  sufficient  water 
to  nearly  fill  the  bottle,  which  is  closed  by  a cork  secured  with  twipe. 

The  official  Lemon  Juice  [Succus  Limonum,  B.  P.,  Limonis 
Succus,  U.  S.  P.)  is  to  be  freshly  expressed  from  the  ripe  fruit,  and 
contain  an  average  of  32.5  grains  of  citric  acid  in  1 fluidounce.  The 
acidity  may  be  ascertained  by  adding  solution  of  potash  or  soda  (the 
strength  of  which  has  been  previously  determined  with  pure  crystals 
of  citric  acid)  till  red  litmus  paper  is  fairly  turned  blue.  Before  ap- 
plying this  test  to  commercial  specimens,  the  absence  of  notable 
quantities  of  sulphuric,  hydrochloric,  acetic,  tartaric,  or  other  acid 
must  be  insured  by  application  of  appropriate  reagents. 

Mistura  Potassii  Citratis,  U.  S.  P.,  is  lemon  juice  completely 
neutralized  by  bicarbonate  of  potassium.  It  is  a slightly  impure  but 
flavored  solution  of  citrate  of  potassium. 

Equivalent  Weights  of  Citric  Acid,  Carbonate  of  Potassium^ 
Bicarbonate  of  Potassium,  Carbonate  of  Sodium,  Bicarbonate  j 
of  Sodium,  and  Carbonates  of  Ammonium,  and  Magnesium  ; \ 

repeated  for  20  parts  of  each  (and,  incidentally,  for  other  propor- 
tions). 


Citric  Acid 

H^CgHftO^HaO — 210 

20 

17 

14 

I 

231 

291 

Carb.  Potas 

(K2CO3;  of  81p.ct.)-^2X3  = 216i 

23k 

20 

16^ 

lU 

' 19f 

28 

341 

Bicarb  Pot 

3(KHC03) — 300 

28k 

24i 

20 

14 

24 

34 

411 

Carb.  Sod.(cryst.) 

(Na3CO3,10H2O)-^2X3....  = 429 

40 

34| 

28h 

20 

134^ 

48| 

60 

Bicarb. Sod 

3(NaHC03) = 252 

24 

20^ 

16J 

113  90 

2Sk 

35 

Carb.  Ammon 

(N4H.,C30,)h-4X3 = 177 

16  J 

llj 

14 

20 

241 

Carb.  Magnes. . . . 

(MgC03)3Mg2H0,  4H3O 

-f-SX3  = 143i 

13^ 

9^ 

6| 

1 

4U 

16i 

20 

Thus  20  parts  (grains,  or  other  weights)  of  citric  acid  neutralize 
23|^  of  carbonate  of  potassium,  28J-  of  bicarbonate  of  potassium,  40 
of  carbonate  of  sodium,  24  of  bicarbonate  of  sodium,  16|  of  carbon- 
ate of  ammonium,  or  13|^  of  carb.  of  magnesium.  Other  quantities 
of  acid  (17,  14,  9J,  16|,  23J,  29i)  saturate  the  amounts  of  salts  men- 
tioned in  the  other  columns,  and  vice  versa. 

This  Table,  the  similar  one  for  tartaric  acid  (p.  286),  and  that 
for  both  acids  [vide  Appendix)  afford  good  illustrations  of  some 
of  the  laws  of  chemical  combination  (p.  40).  The  reader  should 
verify  a few  of  the  numbers  by  calculation  from  the  atomic  weights  ' 
of  the  elements  concerned  in  the  reactions,  remembering  that  the  1 
salts  formed  are  considered  to  be  neutral  in  constitution.  In  medical  J 
practice,  effervescing  saline  draughts  are  often  designedly  prescribed  I 
to  contain  an  amount  of  acid  or  alkali  considerably  in  excess  of  the  | 
proportions  required  for  perfect  neutrality.  : 


CITRATES. 


291 


Analytical  Reactions  ( Tests), 

First  Analytical  Reaction. — To  a dilute  solution  of  any 
neutral  citrate,  or  citric  acid  carefully  neutralized  by  alkali, 
add  solution  of  chloride  of  calcium  and  boil ; a white  pre- 
cipitate, citrate  of  calcium  (Ca3CiJ,  falls.  Treat  the  pre- 
cipitate as  for  tartrate  of  calcium  (p.  281)  ; it  is  not  dissolved 
by  the  potash. 

A mixture  of  citrates  and  tartrates  can  be  separated  by  this  reac- 
tion. They  are  precipitated  as  calcium  salts,  and  the  washed  pre- 
cipitate mixed  with  solution  of  potash,  diluted,  and  filtered ; the  fil- 
trate contains  the  tartrate,  which  is  shown  to  be  present  by  reprecip- 
itation on  boiling.  The  precipitate  still  on  the  filter  is  washed,  dis- 
solved in  solution  of  chloride  of  ammonium,  and  the  solution  boiled  ; 
the  citrate  of  calcium  is  reprecipitated.  The  presence  of  much 
sugar  interferes  with  this  reaction.  A dilute  solution  of  a citrate  is 
not  precipitated  by  chloride  of  calcium  until  the  liquid  is  heated : 
precipitation  from  a strong  solution,  also,  is  not  thoroughly  complete 
without  ebullition  of  the  mixture. 

Second  Analytical  Reaction. — To  a neutral  solution  of  a 
citrate  add  solution  of  nitrate  of  silver ; a white  precipi- 
tate of  citrate  of  silver  (AggCi)  falls.  Boil  the  mixture  ; 
the  precipitate  does  not  turn  black  as  a tartrate  of  silver 
does. 

Other  Analytical  Reactions. — Citric  acid  forms  no  pre- 
cipitate corresponding  with  the  acid  tartrate  of  potassium. 

■ Lime-water,  in  excess,  gives  no  precipitate  with  citric 

acid  or  citrates,  unless  the  solution  is  boiled,  citrate  of 
calcium  being  slightly  soluble  in  cold  but  not  in  hot  w^ater ; 

it  usually  precipitates  tartrates  in  the  cold. Citrates, 

when  heated  with  strong  sulphuric  acid,  do  not  char  imme- 
diately.  Citric  acid  and  citrates  prevent  the  precipita- 

tion of  oxide  of  iron  by  alkalies,  soluble  double  compounds 
being  formed.  The  Ferri  et  Ammonii  Gitras^  U.  S.  P.,  is 

a preparation  of  this  kind. Metallic  citrates  decompose 

when  heated,  carbonates  being  formed  and  carbon  set  free : 
the  odor  of  the  gaseous  products  is  not  so  characteristic  as 
that  of  tartrates. 


QUESTIONS  AND  EXERCISES. 

555.  What  is  the  source  of  citric  acid  ? 

556.  Describe  the  method  by  which  citric  acid  is  prepared,  giving 
diagrams. 


292 


SALTS  OF  ACIDULOUS  RADICALS. 


557.  Illustrate  by  formulae  the  various  classes  of  tartrates  and 
citrates. 

558.  State  the  average-  proportion  of  citric  acid  in  lemon-juice. 

559.  Work  out  the  sums  proving  the  correctness  of  some  of  the 
figures  given  on  page  290  as  showing  the  saturating-powcr  of  citric 
acid  for  various  carbonates. 

560.  What  are  the  tests  for  citrates? 

561.  How  are  the  tartrates  separated  from  citrates? 


PHOSPHORIC  ACID  AND  OTHER  PHOSPHATES. 

Formula  of  Phosphoric  Acid  HgPO^.  Molecular  weight  98. 

Source. — The  source  of  the  ordinary  normal  phosphates  and  of 
phosphorus  itself  [Plios'pliorus,  B.  P.  and  U.  S.  P.)  is  the  normal 
phosphate  of  calcium  (Ca^2P04).  It  is  the  chief  constituent  of  the 
bones  of  animals,  being  derived  from  the  plants  on  which  they  feed, 
plants  again  obtaining  it  from  the  soil.  Compounds  of  phosphorus 
are  also  met  with  in  the  brain,  nerves,  muscles,  blood,  saliva,  and, 
according  to  Kirkes,  even  in  tissues  so  simple  that  one  must  assume 
tfiem  to  be  necessary  constituents  of  the  substance  of  the  primary 
cel].  They  escape  from  the  system  both  in  the  urine  and  faeces. 

Process. — Phosphorus  (P  = 31)  is  obtained  from  bones  by  the  fol- 
lowing processes  : The  bones  are  burnt  to  remove  all  traces  of  animal 
matter.  The  resulting  hone-earth  is  treated  with  sulphuric  acid 
and  water,  by  which  an  acid  phosphate  (CaH42P04),  often  called 
superphosphate  of  lime,  is  produced  : — 

Ca32PO,  + 2H,SO,  = CaH,2PO,  + 2CaSO,. 

The  acid  phosphate  (strained  from  the  sulphate)*  is  mixed  with 
charcoal  and  sand,  and  heated  to  dull  redness  in  an  iron  pot.  At 
this  stage  water  escapes  and  metaphosphate  of  calcium  (Ca.^PO.^, 
see  Index)  remains  : — 

OaH,2PO,  = Ca2P03  + 2II2O. 

The  mixture  is  then  transferred  to  a retort  and  distilled  at  a strong 
red  heat;  silicate  of  calcium  (CaSiOg)  is  formed  and  remains  in  the 
retort,  phosphorus  vapor  is  evolved  and  condensed  under  water,  and 
carbonic  oxide  gas  escapes  : — 

2(Ca2P03)  + 2SiO,  + C^o  = 2CaSi03  + lOCO  + P^. 

It  is  purified  by  melting  under  water  containing  sulphuric  acid  and 
red  chromate  of  potassium. 

Properties. — Phosphorus  is  “a  semitransparent,  colorless,  wax- 
like solid  (in  sticks  or  cakes),  which  emits  white  vapors  when  ex- 
posed to  the  air.  Specific  gravity  1.77.  It  is  soft  and  flexible  at 
common  temperatures,  melts  at  110^,  ignites  in  the  air  at  a tempera- 
ture a little  above  its  melting-point,  burning  wuth  a luminous  flame 
and  producing  dense  Avhite  fumes.  Insoluble  in  water,  but  soluble 
in  ether  and  in  boiling  oil  of  turpentine,”  also  in  bisulphide  of  car- 
bon. It  is,very  poisonous. 


PHOSPHATES. 


298 


Granulated  or  pulverulent  phosphorus  is  obtained  by  placing 
under  equal  parts  of  spirit  and  water  in  a bottle,  standing  the  bottle 
in  warm  water  till  the  phosphorus  melts,  then  inserting  the  stopper 
(glass,  not  cork)  and  shaking  the  whole  till  cold. 

Red  or  Amorphous  Phosphorus. — Ordinary  phosphorus  kept  at 
a temperature  of  about  450®  Fahr.,  in  an  atmosphere  from  which  air 
is  excluded,  becomes  red,  opaque,  insoluble  in  liquids  in  which  ordi- 
nary phosphorus  is  soluble,  oxidizes  extremely  slowly,  and  only 
ignites  when  heated  to  near  500°  Fahr.  It  is  used  in  the  manufac- 
ture of  several  varieties  of  lucifer-matches,  not  emitting  the  poison- 
ous jaw-destroying  fumes  given  by  ordinary  phosphorus. 

Quantivalence. — The  atom  of  phosphorus  is  quinquivalent,  as 
seen  in  the  pentachloride  (PCI5)  and  oxychloride  (PCI3O) ; but  it 
often  exhibits  tri valent  activity,  as  seen  in  the  trichloride  {PCI3) 
and  trihydride  (PH3). 

Molecular  Weight. — Phosphorus  is  an  exception  to  the  rule  that 
the  atomic  weights  (in  grains,  grammes,  etc.)  of  elements  occupy 
similar  volumes  of  vapor  at  similar  temperatures,  the  equivalent 
weight  of  phosphorus  (31)  only  giving  half  such  a volume.  Hence 
while  the  molecular  weights,  that  is,  double  the  atomic  weights, 
of  oxygen  (O2  = 32),  hydrogen  (H2  = 2),  nitrogen  (N2  = 28),  etc. 
give  a similar  bulk  of  vapor  at  any  given  temperature  ; the 
double  atomic  weight  of  phosphorus  (P2  = G2)  only  gives  half  this 
bulk ; that  is,  four  times  the  atomic  weight  of  phosphorus  must  be 
taken  to  obtain  the  whole  bulk.  It  would  appear  therefore  that  the 
molecule  of  phosphorus  contains  four  atoms  (P^  = 124).  As  with 
sulphur,  however,  phosphorus  in  the  state  ordinarily  known  to  us 
may  be  abnormal,  and  a variety  yet  be  found  in  which  the  molecular 
weight  is  double  the  atomic  weight. 

Phosphoric  Acid. 

The  chief  use  of  phosphorus  in  pharmacj^  is  in  the  for- 
mation of  Diluted  Phosphoric  Acid.  Phosphorus  is  boiled 
with  nitric  acid  and  water  until  dissolved.  The  solution, 
evaporated  to  a low  bulk  to  remove  nitrous  compounds, 
and  rediluted  so  as  to  contain  nearly^  14  (13.8)  per  cent,  of 
acid  (H3POJ,  equivalent  to  10  per  cent,  of  phosphoric  an- 
hydride (P.2O5),  constitutes  the  Acidum  Phosphoricunt  'Di- 
lutum.^  B.  P.  and  U.  S.  P.,  a colorless  sour  liquid  of  specific 
gravity  1.08  (1.05G  U.  S.  P.).  If  the  necessaiy  appliances 
are  at  hand,  four  or  five  ounces  of  this  acid  may  be  pre- 
pared as  follows : A quarter  of  a pint  is  made  by  boiling 
together,  in  a retort  attached  to  a Liebig^s  condenser,  103 
grains  of  phosphorus,  fluidounce  of  the  official  nitric 
acid,  and  2 ounces  of  water.  When  about  1 oz.  of  water 
has  distilled  over,  it  should  be  returned  to  the  retort,  and 
the  operation  repeated  until  the  phosphorus  has  disap- 
peared. 


25* 


294 


SALTS  OF  ACIDULOUS  RADICALS. 


3P4  + 20HNO3  + 8H,0  = I2H3PO,  + 20NO 

Phos-  Nitric  acid.  Water.  Phosphoric  Nitric 

phorus.  acid.  oxide. 

The  liquid  remaining  in  the  retort  is  then  transferred  to 
a dish  (preferably  of  platinum),  evaporated  down  to  about 
half  an  ounce,  and,  lastly,  diluted  with  distilled  water  to  5 
fluidouncesJ 

The  use  of  the  water  in  this  process  is  to  moderate  the  reaction. 
Strong  hot  nitric  acid  oxidizes  phosphorus  with  almost  explosive 
rapidity,  hence  must  not  only  be  diluted  in  the  first  instance,  but  be 
rediluted,  from  time  to  time,  to  prevent  its  becoming  too  strong  by 
loss  of  water.  Deficiency  of  nitric  acid  must  also  be  avoided,  or^ 
some  phosphorous  acid  (H.^PHOg)  will  be  formed.  A flask,  in  the 
neck  of  which  a funnel  is  inserted,  and  a second  funnel  inverted,  so  i 
that  its  mouth  rests  within  the  mouth  of  the  first,  is  an  efficient  and 
convenient  arrangement  of  apparatus  for  this  process,  especially  if 
the  ope^i'ation  be  conducted  slowly. 

Solution  of  phosphoric  acid  evaporated  leaves  a residue  which 
melts  at  a low  red  heat,  yielding  pyrophosphorzc  aczd,  and,  finally, 
metaphosphoric  acid  ( facial  Phosphoric  Acid). 

Quanhvalence. — The  elements  represented  by  the  formula  PO^ 
are  those  characteristic  of  phosphates.  The  grouping  is  trivalent ; 
hence  there  may  exist  trimetallic  or  normal  phosphate  (M'gPOJ, 
dimetallic  acid  phosphates  (M'.^HPO^),  monometallic  acid  phos- 
phates (M'H2P04),  and,  lastly,  trihydric  phosphate  (HgPO^),  or 
common  phosphoric  acid.  These  are  the  ordinary  phosphates  met 
with  in  nature  or  used  in  pharmacy ; the  rarer  pyrophosphates, 
metaphosphates,  phosphites,  and  hypophosphites  will  be  mentioned 
subsequently. 

Analytical  Reactions  ( Tests), 

First  Analytical  Reaction. — To  an  aqueous  solution  of  a 
phosphate  (e.g.  add  solution  of  sulphate  of  mag- 

nesium with  which  chloride  of  ammonium  and  ammonia 
have  been  mixed  ; a white  crystalline  precipitate  of  ammo- 
nio-magnesium  phosphate  falls  (MgAmPOJ. 

Chloride  of  ammonium  is  added  to  prevent  the  precipitation  of 
hydrate  of  magnesium.  Arseniates,  from  their  close  analogy  to 
phosphates,  give  a similar  precipitate  with  the  magnesium  reagent. 

Second  Analytical  Reaction To  a neutral  aqueous  solu- 

tion of  a phosphate  add  solution  of  nitrate  of  silver;  light- 
yellow  phosphate  of  silver  (AggPOJ  is  precipitated.  To  a 
portion  of  the  precipitate  add  ammonia  ; it  dissolves.  To 
another  portion  add  nitric  acid  ; it  dissolves. 

By  this  reaction  phosphates  may  be  distinguished  from  their  close 
allies  the  arseniates,  arseniate  of  silver  being  of  a chocolate  color. 


PHOSPHATES. 


295 


Third  Analytical  Reaction. — a solution  (in  a few 
drops  of  acid)  of  a phosphate  insoluble  in  water  {e.g. 
Ca32POJ  add  an  alkaline  acetate  (that  is,  a mixture  of  soda 
or  ammonia  with  excess  of  acetic  acid),  and  then  a drop  or 
two  of  solution  of  perchloride  of  iron ; yellowish-white  ferric 
phosphate  (Fe2POJ  is  precipitated. 

Too  much  of  the  ferric  chloride  must  not  be  added,  or  ferric 
acetate  will  be  produced,  in  which  ferric  phosphate  is  to  some  extent 
soluble. 

To  remove  the  whole  of  the  phosphoric  radical  from  the 
solution,  add  ferric  chloride  so  long  as  a precipitate  is  pro- 
duced, and  then  boil  the  mixture  ; ferric  phosphate  and 
ferric  oxyacetate  are  precipitated. 

To  obtain  confirmatory  evidence  of  the  presence  of  phos- 
phate in  this  precipitate,  and  to  separate  the  phosphoric 
radical  as  a pure  un mixed  phosphate,  collect  the  precipitate 
on  a filter,  wash,  drop  some  solution  of  ammonia  on  it,  then 
sulphydrate  of  ammonium,  and  finally  wash  with  water; 
black  ferrous  sulphide  remains  on  the  filter,  while  phosphate 
of  ammonium  occurs  in  the  filtrate.  To  the  filtrate  add  a 
mixture  of  solutions  of  sulphate  of  magnesium  and  chlo- 
ride of  ammonium,  and  well  stir;  ammonio-magnesian 
phosphate  is  precipitated. 

The  above  reaction  is  useful  in  the  analysis  of  bone-earth,  other 
earthy  phosphates,  phosphate  of  iron,  and  all  phosphates  insoluble  in 
water.  Only  arseniates  give  similar  appearance  ; but  the  acid  solu- 
tion of  these  may  be  decomposed  by  sulphuretted  hydrogen  (H^S), 
especially  after  agitation  with  sulphurous  acid  and  subsequent  ebul- 
lition. 

Other  Analytical  Reactions. — Solutions  of  barium  and 
calcium  salts  give,  with  aqueous  solutions  of  phosphates, 
white  precipitates  of  the  respective  phosphates  BaHPO^, 
or  Bas^PO^,  and  CaHPO^,  or  Ca32PO^,  all  of  which  are 
soluble  in  acetic  and  the  stronger  acids. 


QUESTIONS  AND  EXERCISES. 

562.  State  the  source  of  phosphorus. 

563.  Give  equations  or  diagrams  explanatory  of  the  isolation  of 
phosphorus  from  its  natural  compounds. 

564.  What  is  the  composition  of  farmers’  “ superphosphate,”  and 
how  prepared  ? 

565.  Enuijierate  the  properties  of  ghqsphorus. 


296 


SALTS  OF  ACIDULOUS  RADICALS. 


566.  Mention  some  solvents  of  phosphorus. 

567.  How  is  the  official  Diluted  Phosphoric  Acid  made  ? 

568.  Describe  the  precautions  necessary  to  be  observed  in  making 
this  acid. 

569.  What  is  the  strength  of  the  official  acid  ? 

570.  AVrite  formulae  illustrative  of  all  classes  of  orthophosphates. 

571.  Mention  the  chief  tests  for  soluble  and  insoluble  phosphates. 

572.  By  what  reactions  may  phosphates  be  distinguished  from 
arseniates  ? 


Vanadium^  Y,  51.3,  is  a very  rare  element,  and  is  here 
mentioned  only  because  of  its  exceedingly  interesting  rela- 
tionship to  nitrogen, phosphorus, and arsenicuin.  Discovered 
but  not  isolated  by  Sefstroin,  and  its  compounds  investi- 
gated by  Berzelius,  it  has  only  recently  been  obtained  in 
the  free  state  and  fully  studied  by  Hoscoe. 


Oxides  of  Nitrogen. 

Orthophosphates  Hg'PO^ 
Pyrophosphates  H/P.p^ 
Metaphosphates  K'POg 


Oxides  of  Vanadium 

vaaA.A03,va,VO 
Orthovanadates  R/VO^ 
Pyrovanadates  R/A^^O^ 
Metavanadates  R'A^O, 


Isomorphous  Minerals. 

Ajmtite  3(Ca32POJ,CaFl2 

Pyromorphite  3(Pb32POj,PbCl2 
Mimetesite  3(Pb32AsOj,PbCl2 
Yanadinite  3(Pb32YO^^,PbCl2 


BORACIC  ACID  AND  OTHER  BORATES. 

Formula  of  Boracic  Acid  H3BO3.  Molecular  weight  62. 

The  composition  of  artificial  boracic  acid  is  expressed  by  the  for- 
mula H3BO3 ; but  at  a temperature  of  212^  F.  this  body  loses  the  ele- 
ments of  water  and  yields  metaboracic  acid,  HBO2.  ^J'he  latter  acid 
exists  in  the  jets  of  steam  (fumerolles  or  suffioni)  that  issue  from 
the  earth  in  some  districts  of  Tuscany,  and  collects  in  the  water  of 
the  lagoni  (lagoons  or  little  lakes)  formed  at  the  orifice  of  the  steam- 
channel.  This  acid  liquid  evaporated  by  aid  of  the  waste  natural  steam 
and  neutralized  by  carbonateof  sodium  gives  common  borax  (2NaB02, 
2HB02,9H20),  possibly  an  acid  metaborate  of  sodium,  with  water 
of  crystallization.  It  occurs  ‘‘  in  transparent  colorless  crystals, 
sometimes  slightly  effloresced,  with  a weak  alkaline  reaction  ; in- 
soluble in  rectified  spirit,  soluble  in  water.”  Borax  is  also  found 
native,  particularly  in  Thibet.  Fused  borax  readily  dissolves  metallic 
oxides,  as  will  have  been  already  noticed  in  testing  for  cobalt  and 


BORATES. 


297 


manganese.  Hence,  besides  its  use  in  medicine  [Sodii  Boras,  U.  S. 
P. ; Borax ; Mel  Boracis,  B.  P.,  or  Mel  Sodii  Boratis,  U.  S.  P., 
and  Glycerinum  Boracis,  B.  P.)  , it  is  employed  as  a flux  in  refining 
and  other  metallurgic  and  ceramic  operations. 

Qaantivalence. — The  boracic  radical  is  trivalent  (BO3'"),  the 
metaboracic,  univalent  (BO^') ; they  have  not  been  isolated.  The 
element  boron,  like  carbon,  occurs  in  the  amorphous,  graphitoidal, 
and  crystalline  conditions.  It  is  a trivalent  element  (B'"),  yielding 
definite  salts,  such  as  the  chloride  (BCI3)  and  fluoride  (BF3).  Its 
atomic  weight  is  11. 

Heactions. 

First  Synthetical  Reaction, — To  a hot  solution  of  a crys- 
tal of  borax  add  a few  drops  of  sulphuric  acid  and  set 
aside;  on  cooling,  cr^’stalline  scales  of  boracic  acid  (H3BO3) 
are  deposited.  They  may  be  purified  by  collecting  on  a 
filter,  slightly  washing,  drying,  digesting  in  hot  alcohol, 
filtering,  and  setting  aside ; pure  boracic  acid  (B.  P.)  is 
deposited.  The  acid  may  also  be  recrystallized  from  w.ater. 
Fifty^  grains  dissolved  in  one  ounce  of  rectified  spirit  con- 
stitutes “ Solution  of  Boracic  Acid,’^  B.  P. 

When  heated,  these  crystals  lose  water  and  yield,  first,  metaboracic 
acid  (HBO2),  and,  subsequently,  when  fused,  boracic  anhydride  (B2O3). 

Boracic  acid  is  very  weak.  It  only  slowly  decomposes  carbonates, 
and  resembles  alkaline  compounds  in  coloring  turmeric  brown.  In- 
deed the  alkalinity  of  borax  is  as  great  as  if  it  contained  no  acidu- 
lous radical  whatever. 

Second  Synthetical  Reaction, — Mix  together  1 part  of 
boracic  acid,  4 of  acid  tartrate  of  potassium,  and  10  or  20 
of  water;  evaporate  to  a syrupy  consistence,  spread  on 
plates,  and  set  aside  for  dry  scales  to  form.  The  resulting 
substance  is,  in  water,  far  more  readily  soluble  than  either 
of  its  constituents,  and  is  known  as  horo-tartrate  of  potas- 
sium,^ soluble  tartar,^  or  soluble  cream  o f tartar.  The  Prus- 
sian tartarus  boraxatis  dififers  from  the  foregoing  French 
variety  in  containing  1 part  of  borax  to  3 of  acid  tartrate 
of  potassium. 


Analytical  Reactions  ( Tests). 

First  Anahjtical  Reaction, — Dip  a piece  of  turmeric  paper 
(paper  soaked  in  tincture  of  turmeric  tubers  and  dried) 
into  a solution  of  boracic  acid ; it  is  colored  brown-red,  as 
by  alkalies. 

The  usual  way  of  applying  this  test  is  as  follows:  Add  to  any 
borate  a few  drops  of  hydrochloric  acid,  immerse  half  of  a slip  of 


298 


SALTS  OF  ACIDULOUS  RADICALS. 


turmeric  paper  in  the  liquid,  then  remove  the  hydrochloric  acid  by 
drying  the  paper  over  a flame.  Concentrated  hydrochloric  acid  and 
ferric  chloride  produce  a somewhat  similar  effect. 

Second  Analytical  Reaction, — To  a fragment  of  a borate 
or  metaborate  (borax,  for  example)  in  a small  dish  or  watch- 
glass  add  a drop  of  sulphuric  acid  and  then  a little  alcohol, 
warm  the  mixture  and  set  light  to  the  spirit;  the  resulting 
flame  will  be  tinged  of  a greenish  color  at  its  edges  by  the 
volatilized  boracic  acid  or  boracic  anhydride. 

The  liquid  should  be  well  stirred  while  burning.  Salts  of  copper 
and  some  metallic  chlorides  produce  a somewhat  similar  color. 

Other  Analytical  Reactions.  — In  solutions  of  borax, 
barium  salts  give  a white  precipitate  of  barium  metaborate 
(Ba2B02)  s^^lwble  in  acids  and  alkaline  salts.  Nitrate  of 
silver  gives  metaborate  of  silver  (AgBO.^)  soluble  in  nitric 
acid  and  in  ammonia.  Chloride  of  calcium,  if  the  solution 
is  not  too  dilute,  gives  white  borate  of  calcium. 


QUESTIONS  AND  EXERCISES. 

573.  Illustrate  the  relation  of  vanadium  to  nitrogen  by  formulae 
of  compounds  of  each  element. 

574.  Describe  the  preparation  of  borax. 

575.  Give  the  formulae  of  boracic  acid,  metaboracic  acid,  and 
borax. 

576.  Mention  the  tests  for  borates  or  metaborates. 

The  foregoing  acids  and  other  salts  contain  the  only  acidulous 
radicals  that  are  commonly  met  with  in  analysis  or  in  ordinary 
pharmaceutical  operations.  There  are,  hoioever,  many  others 
which  occasionally  present  themselves.  The  chief  of  these  will  now 
he  shortly  noticed ; they  are  arranged  in  alphabetical  order  to 
facilitate  reference. 

SALTS  OF  RARER  ACIDULOUS  RADICALS. 

Benzoic  Acid  (HC^H^O^)  and  other  Benzoates. — Slowdy 
heat  a fragment  of  benzoin  (Beiizoinuni,  B.  P.  and  U.  S.  P.) 
in  a test-tube;  benzoic  acid  {Acidum  Benzoicum^  B.  P. 
and  U.  S.  P.)  rises  in  vapor  and  condenses  in  small,  wdiite, 
feathery  plates  and  needles,  on  the  cool  sides  of  the  tube. 
If  the  benzoin  is  first  mixed  with  twice  its  weight  of  sand 
or  roughly  powdered  pumice-stone,  and  the  heat  very 


BENZOATES. 


299 


cautiously  applied,  the  product  will  be  less  likely  to  be 
burnt,  and  a larger  quantity  be  obtained. 

A more  economical  process  is  to  boil  the  benzoin  with 
one-fourth  its  weight  of  lime,  filter,  concentrate,  decompose 
the  solution  of  benzoate  of  calcium  by  hydrochloric  acid, 
collect  the  precipitated  benzoic  acid,  press  between  paper, 
dry,  and  sublime  in  a tube  or  other  vessel. 

2HC,H,0,  + Ca2HO  Ca2C,H,0,  + 2H,0 

Benzoic  acid  Hydrate  of  Benzoate  of  Water. 

(impure).  calcium.  calcium, 

Ca2C,II,0,  + 2HC1  = CaCl,  + 2HC,H503 

Benzoate  of  Hydrochloric  Chloride  of  Benzoic  acid 

calcium.  acid.  calcium,  (pure). 

Benzoic  acid  is  also  prepared  on  a large  scale  artificially  from 
naphthalin,  one  of  the  crystalline  by-products  in  the  distillation  of 
coal  for  gas.  The  naphthalin  is  oxidized  by  nitric  acid  to  naphthalic 
or  phthalic  acid : — 

O.oHi,  + 40,  = 

Naphthalin.  Oxygen.  Phthalic  acid.  Oxalic  acid. 

The  phthalic  acid  is  neutralized  by  lime  and  the  phthalate  of  cal- 
cium heated  with  hydrate  of  calcium  in  a covered  vessel  at  a tem- 
perature of  about  640^  for  several  hours.  Benzoate  and  carbonate 
of  calcium  are  formed,  and  from  the  powder  benzoic  acid  set  free  by 
action  of  hydrochloric  acid. 

2Ca08H,0,  4-  Ca2HO  = Ca2C,H,02  -f  2CaCO., 

Phthalate  of  Hydrate  of  Benzoate  of  Carbonate  of 

calcium.  calcium.  calcium.  calcium. 

The  crystalline  deposit  formed  when  essential  oil  of  almonds 
(hydride  of  benzoyl  or  benzoic  aldehyd)  is  exposed  to  the  air  is  ben- 
zoic acid. 

2C,H50H  + 0,  = 20,H50HO  or  2HC,H,0, 

Hydride  of  Oxygen.  Hydrate  of  Benzoic 

benzoyl.  benzoyl.  acid. 

There'  is  always  associated  with  the  product  a minute  quantity  of  a 
volatile  oil  of  agreeable  odor,  suggesting  that  of  hay. 

Benzoate  of  Ammonium. — To  a little  benzoic  acid  add  a 
few  drops  of  solution  of  ammonia  ; it  readily  dissolves, 
forming  benzoate  of  ammonium  {Ammonii  Benzoas^  U.  S. 
P.)  (NH,C,H,0,). 

HC.H^O,  + NIT,HO  = NH^C,H,0,  + H,0 

Benzoic  acid.  Ammonia.  Benzoate  of  Water. 

ammonium. 

On  evaporation,  acid  crystals  or,  ammonia  being  added, 
neutral  crystals  of  benzoate  of  ammonium  are  deposited. 

Propertiei^. — Benzoic  acid  is  also  soluble  in  other  alkaline 
liquids,  forming  benzoates.  It  is  slightly  soluble  in  cold 


300 


SALTS  OF  ACIDULOUS  RADICALS. 


water,  more  so  in  hot,  and  readily  soluble  in  rectified  spirit. 
It  melts  at  248°  F.,  and  boils  at  462°,  evaporating  with 
only  a slight  residue. 

Tests, — The  following  are  the  tests  for  benzoic  acid  : To 
a portion  of  the  above  solution  of  benzoate  of  ammonium 
add  a drop  or  two  of  sulphuric  or  hydrochloric  acid ; a 
white  crystalline  precipitate  of  benzoic  acid  separates.  To 
another  portion,  carefully  made  neutral,  add  a dro[)  or  two 
of  neutral  solution  of  perchloride  of  iron  ; reddish  ferric 
benzoate  is  precipitated.  Benzoic  acid  is  distinguished 
from  an  allied  body,  cinnamic  acid  (occurring  in  Balsams 
of  Peru,  Tolu,  and  Storax),  bj"  not  yielding  hydride  of 
benzoyl  (C^H^OH)  (oil  of  bitter  almonds)  when  distilled 
with  chromic  acid — that  is,  with  a mixture  of  red  chromate 
of  potassium  and  sulphuric  acid. 

Carminic  Acid  — This  is  the  coloring  principle  of  cochi- 

neal [Coccus,  B.  P.  and  U.  S.  P.).  The  carmine  oi  trade,  when 
unadulterated  [vide  Pharmaceutical  Journal,  1859-60,  p.  546),  is 
carminic  acid  united  with  about  five  per  cent,  of  alumina,  or  occa- 
sionally, of  oxide  of  tin  or  albumen.  It  should  be  wholly  soluble  in 
solution  of  ammonia.  Carmine,  with  French  chalk,  or  starch,  con- 
stitutes face-rouge  or  animal  rouge. 

Merrick  tests  the  relative  value  of  several  samples  of  cochineal  or 
carmine  by  observing  how  much  solution  of  permanganate  of  potas- 
sium is  required  to  change  the  color  of  a decoction  to  faint  pink. 

Oetraric  Acid  (H^C^^H^oCig)  is  the  bitter  principle  of  Iceland 
moss  [Cetraria,  B.  jP.  and  U.  S.  P.).  In  the  lichen  it  is  associated) 
with  much  starch.  j 

Chrysophanic  Acid  (CjoHj^Og?). — This  acid  is  the  chief  coloring- i 
matter  of  various  species  of  rhubarb  root  [Rhei  Radix,  B.  P.,  Rheum,  v 
U.  S.  P.)  and  parmelia.  It  may  be  obtained  in  crystals  of  a golden- f 
yellow  color,  hence  the  name  (from  chrusos,  gold,  and  |i 

phaind,  I shine).  Its  synonyms  are  Rhaponticin,  Rheic  acid,\} 
Rhein,  Rheumin,  Rheuharharic  acid,  Rheuharharin,  R^imicin.i^ 
Chrysophanic  acid,  black,  red-brown,  and  red  resins  [Aporetine,'^ 
Phceoretine,  and  Erythroretine),  a bitter  principle,  and  tannic  acid  ' 
are  considered  to  be  the  conjoint  source  of  the  therapeutic  properties  i 
of  rhubarb.  i 

Cyanic  Acid  (IlCyO)  and  other  Cyanates. — The  vain-  i 
able  reducing-power  of  cyanide  of  potassium  (KCy)  (or  i 
ferrocyanide,  K^Fcy)  on  metallic  compounds  is  due  to  the  I 
avidity  with  which  cyanate  (KCyO)  is  formed. 

Process. — Fuse  a few  grains  of  cyanide  of  potassium  in 
a small  jiorcelain  crucible,  and  add  powdered  oxide  of  lead  ; i 
a globule  of  metallic  lead  is  at  once  set  free,  excess  of  the 
oxide  converting  the  whole  of  the  cyanide  of  potassium  into 
cyanate  of  potassium. 


HIPPUR  AXES. 


301 


Urea. — Cyanate  of  potassium  (KCNO),  or,  better,  cyanate  of  lead 
(Pb2CNO),  treated  with  sulphate  of  ammonium,  yields  cyanate  of 
ammonium  (NH^ONO) ; and  solution  of  cyanate  of  ammonium, 
when  simply  heated,  changes  to  artificial  urea  (CH^N20),  the  most 
important  constituent  of  urine,  and  the  chief  form  in  which  the  nitro- 
gen of  food  is  eliminated  from  the  animal  system.  The  process  will 
be  more  fully  described  subsequently  in  connection  with  urea. 

Formic  Acid  (HCHO2). — The  red  ant  [Formica  rufa)  and  several 
other  insects,  when  irritated,  eject  a strongly  acid,  acrid  liquid,  hav- 
ing a composition  expressed  by  the  above  formula,  and  which  has 
appropriately  received  the  name  of  formic  acid  ; it  is  also  contained 
in  the  leaves  of  the  stinging-nettle. 

Process, — It  may  be  artificially  prepared  by  heating  equal 
weights  of  oxalic  acid  and  gl^^cerine  to  a temperature  of 
from  212*^  to  220^  for  fifteen  hours.  The  glycerine  has, 
apparently,  no  chemical  action,  but,  for  some  unknown 
reason,  induces  decomposition  of  the  oxalic  acid  at  a lower 
temperature  than  would  otherwise  be  necessary  ; at  a higher 
temperature  the  formic  acid  itself  is  decomposed.  On  dis- 
tilling the  mixture  with  water,  the  formic  acid  slowly  passes 
over.  The  dilute  acid  may  be  concentrated  by  neutralizing 
with  carbonate  of  lead,  filtering,  evaporating  to  a small 
bulk,  collecting  the  deposited  crystalline  formate  of  lead, 
drying,  decomposing  in  a current  of  sulphuretted  hydro- 
gen, and  separating  the  resulting  syrupy  acid,  or  distilling 
the  formate  of  lead  with  strong  sulphuric  acid. 

= HCHO2  + CO, 

Oxalic  Formic  Carbonic 

acid.  acid.  acid  gas. 

Formic  acid  may  be  instructively  though  not  economically  pre- 
pared by  the  oxidation  of  methylic  alcohol  (wood-spirit),  just  as 
acetic  acid  and  valerianic  acid  are  obtained  from  ethylic  alcohol  and 
amylic  alcohol  respectively. 

CH3HO  4-  O2  = HCHO2  + H2O 

Wood  Oxygen.  Formic  Water, 

spirit.  acid. 

Tests. — Formic  acid  does  not  char  when  heated  alone  or  with  sul- 
phuric acid,  but  splits  up  into  carbonic  oxide  gas  and  water.  It  is 
recognized  by  this  property  and  by  its  reducing-action  on  salts  of  gold, 
platinum,  mercury,  and  silver.  It  is  solid  below  32^. 

Gallic  Acid. — See  Tannic  Acid, 

Hemidesmic  Acid. — The  supposed  active  principle  of 
hemidesmus  root  {Hemidesmi  Radix^  B.  P.). 

Hippuric  Acid  (HCgHgNOg)  is  a constituent  of  human  urine 
(much  increased  on  taking  benzoic  acid),  but  is  best  prepared  from 
the  urine  of  the  horse  (hence  the  name,  from  hippos,  a horse), 

or,  better,  from  that  of  the  cow.  To  such  urine  add  a little  milk  of 

26 


302  SALTS  OF  RARER  ACIDULOUS  RADICALS. 

lime,  boil  for  a few  minutes,  remove  precipitated  phosphates  by  filtra- 
tion, drop  in  hydrochloric  acid  until  the  liquid,  after  well  stirring,  is 
exactly  neutral  to  test-paper,  concentrate  to  about  one-eighth  the 
original  bulk,  and  add  excess  of  strong  hydrochloric  acid  ; impure 
hippuric  acid  is  deposited.  From  a solution  of  the  impure  acid  in 
hot  water  chlorine  gas  removes  the  color,  and  the  liquid  deposits 
crystals  of  pure  hippuric  acid  on  cooling.  Its  constitution  is  that  of 
henzoic  glycocine,  C.^H2(C7H50)  (NH2)02. 

Tests. — To  a solution  of  hippurate  add  neutral  solution  of  ferric 
chloride;  a brown  precipitate  (ferric  hippurate)  results.  Salts  of 
silver  and  mercury  give  white  precipitates.  Heat  hippuric  acid  in  a 
test-tube ; it  chars,  benzoic  acid  sublimes,  and  vapors  of  characteristic 
odor  are  evolved;  they  contain,  amongst  other  bodies,  hydrocyanic 

acid  and  a substance  smelling  somewhat  like  Tonka  bean. The 

crystalline  form  of  hippuric  acid  is  characteristic  ; it  will  be  described 
in  connection  with  the  subject  of  urine. 


QUESTIONS  AND  EXERCISES. 

577.  Give  the  preparation,  composition,  properties,  and  tests  of 
benzoic  acid,  employing  equations  or  diagrams. 

578.  What  is  the  nature  of  carmine  ? 

579.  Name  the  bitter  principle  of  Iceland  moss. 

580.  Mention  the  coloring  principle  of  rhubarb. 

581.  To  what  is  rhubarb  considered  to  owe  its  medicinal  activity  ? 

582.  How  is  cyanate  of  potassium  prepared,  how  converted  into 
an  ammonium  salt,  and  what  the  relations  of  the  latter  to  urea  ? 

583.  Give  the  formulae  of  cyanic  acid,  cyanate  of  ammonium,  and 
urea. 

584.  What  is  the  chemical  formula  of  formic  acid  ? 

585.  Describe  the  artificial  production  of  formic  acid. 

586.  Describe  the  relation  of  formic  acid  to  wood-spirit. 

587.  State  the  sources,  characters,  and  tests  of  hippuric  acid. 


Hydroferrocyanic  Acid  (H^Fe"Cy6,  H^Fcy"")  and  other 
Ferrocyanides. — The  ferrocyanide  of  most  interest  is  that  of  potas- 
sium [Potassii  Ferrocyanidum,  U.  S.  P.),  the  yellow  prussiate  of 
potash  [Potassce  Prussias  Flava,  B.  P.)  (K^FeCgNg,  SH.^O),  the 
formation  of  which  was  alluded  to  in  connection  with  hydrocyanic 
acid  (see  page  248).  It  cannot  be  regarded  as  simply  a double  salt 
of  cyanide  of  potassium  with  cyanide  of  iron  (FeCy2,  4KCy),  its 
chemical  properties  being  entirely  different  from  either  of  those  sub- 
stances; moreover,  unlike  cyanide  of  potassium,  it  is  not  poisonous. 
Most  of  its  reactions  point  to  the  conclusion  that  its  iron  and  cyano- 
gen are  intimately  united  to  form  a definite  quadrivalent  radical  ap- 
propriately termed  ferrocyanogen  (FeCyg,  or  Fey).  One  part  of 
ferrocyanide  of  potassium  in  20  of  water  forms  the  official  “Solution 
of  Yellow  Prussiate  of  Potash,”  B.  P.  | 


FERRIDCYANIDES. 


303 


Tests. — Many  of  the  ferrocj^anides  are  insoluble,  and 
are  therefore  precipitated  when  solution  of  ferrocyanide  of 
potassium  is  added  to  the  various  salts.  Those  of  iron  and 
copper,  being  of  characteristic  color,  are  adopted  as  tests  of 
the  presence  of  the  metals  or  of  the  ferrocyanogen,  as  the 
case  may  be. 

3K,Fcy  -f  2(Fe,3SOJ  = Fe.Fcyg  + 6K,SO,. 

To  solution  of  ferroG3'anide  of  potassium  add  a ferric  salt; 
ferrocyanide  of  iron  (Fe^Fcy3)  (Fi’ussian  Blue)  {Ferri  ferro- 
cyanidum.^  U.  S.  P.)  is  precipitated. 

To  another  portion  add  solution  of  a copper  salt ; red- 
dish-brown ferrocyanide  of  copper  (Cu^Fcy)  is  precipitated. 

Note. — The  ferrocyanogen  in  ferrocyanide  of  potassium  is  broken 
up  when  the  salt  is  heated  with  sulphuric  acid,  carbonic  oxide  being 
evolved  if  the  acid  is  strong,  and  hydrocyanic  acid  if  weak  : — 

K^FeCfiNs  + m,0  + GH^SO,  = 2K,SO^  + FeSO, 

-f  3(NHJ,SO,  -f  6CO. 

2K,FeCy6  + hH^SO,  + xH,0  = FeK.FeCyg  + 6KHSO, 

-f  6HCy  X xHaO. 

Hydrocyanic  Acid  has  already  been  described.  ( Vide  p.  249.) 

Carbonic  oxide  (CO). — Heat  two  or  three  fragments  of  ferrocya- 
nide of  potassium  with  eight  or  ten  times  their  weight  of  sulphuric 
acid,  and,  as  soon  as  the  gas  begins  to  be  evolved,  remove  the  test- 
tube  from  the  flame  ; for  the  action,  when  once  set  up,  proceeds  some- 
what tumultuously.  Ignite  the  carbonic  oxide  at  the  mouth  of  the 
tube  ; it  burns  with  a pale  blue  flame,  the  product  of  combustion  being 
carbonic  acid  gas  (CO^). 

Carbonic  oxide  is  a direct  poison.  It  is  generated  whenever  coke, 
charcoal,  or  coal  burns  with  an  insufficient  supply  of  air.  Hence  the 
danger  of  open  fires  in  the  more  or  less  closed  apartments  of  ordinary 
dwellings. 

Carbonic  oxide  may  also  be  obtained  from  oxalic  acid.  ( Vide  p. 
283.) 

Hydroferridcyanic  Acid  (ngFe"'2C^y^29  H^gFdcy^^) 
AND  OTHER  Ferridcyanides — Pass  clilorinc  gas  slowly 
through  solution  of  ferroc^'anide  of  potassium  until  the 
liquid,  after  frequent  shaking,  ceases  to  give  a blue  precipi- 
tate, when  a minute  portion  is  taken  out  on  the  end  of  a 
glass  rod  and  brought  into  contact  with  a drop  of  a dilute 
solution  of  a ferric  salt ; it  now  contains  ferridcyanide  of 
potassium  (K6Fe'"2^yj,2,  or  K^gFdcy^^),  red  prussiate  of 
potash  (B.  P.),  as  it  is  termed  from  the  color  of  its  crystals. 
Excess  of  chlorine  must  be  carefully  avoided,  as  chloride 
of  cyanogen  and  other  compounds  are  then  formed. 

2K',Fe"Cy'g  + Cl'^  = 2K'CP  + K'gFe'^^Cy'.a- 


304  SALTS  OF  RARER  ACIDULOUS  RADICALS. 

Note. — The  removal  of  two  atoms  of  potassium  from  theferrocya- 
nide  is  the  only  change  of  composition  that  occurs ; but  the  ferrocya- 
nogen  is  altered  in  quality,  its  iron  passing  from  the  ferrous  to  the 
ferric  condition,  from  bivalent  to  trivalent  activity,  a condition  in 
which  it  no  longer  precipitates  ferric  salts,  but,  on  the  other  hand, 
gives  a dark-blue  precipitate  with  ferrous  salts.  The  radical  is  dis- 
tinguished as  ferridcyanogen. 

Ferridcyanide  of  potassium  may  also  be  prepared  by  a modifica- 
tion of  the  foregoing  method  in  which  nascent  instead  of  free  chlorine 
is  employed  (Wenzell).  Take  of  Bichromate  of  Potash  1 part,  Fer- 
rocyanide  of  Potassium  Cryst.  5.72  parts.  Hydrochloric  Acid,  of 
spec.  grav.  1.16,  3 parts,  by  weight.  Water  60  parts.  Dissolve  the 
two  salts  in  hot  water,  add  the  acid,  heat  to  boiling,  continuing  the 
ebullition,  replacing  the  water  evaporated  during  *the  process  until 
a portion  of  the  filtered  liquid  is  not  precipitated  on  the  addition  of 
sesquichloride  of  iron.  When  reaction  is  completed,  filter  the  liquid, 
and  wash  the  hydrate  of  chromium,  unite  the  liquids,  and  concentrate 
to  crystallization.  If  the  evaporated  liquid  possess  an  acid  reaction, 
the  addition  of  caustic  potash,  in  sufficient  quantity  to  cause  a weak 
alkaline  reaction,  will  greatly  facilitate  the  subsequent  crystalli- 
zation. 

6(K,FeCye)  + K,Cr,0,  + 8HC1  = 3(K,Fe,Cy,,)  . 

+ 8KC1  + H,0  + Cr,6HO. 

Test, — To  a portion  of  the  solution  add  solution  of 
ferrous  sulphate  ; a precipitate  falls.  This  precipitate  is 
ferridcyanide  of  iron  (TurnbulPs  blue),  Fe^sFe^'^Cy^^?  or 
re''3Fdcy^h 

KgFdcy  + 3FeSO^  = FegPdcy  4-  3K^SO^. 

It  will  be  noticed  that  the  change  in  the  condition  of  the  iron 
keeps  up  the  balance  of  the  atomic  values  of  the  various  parts  of  the 
radicals  or  of  the  salts ; the  quantivalential  equilibrium  is  maintained. 

A solution  of  1 of  ferridcyanide  of  potassium  in  20  of  water  con- 
stitutes the  “Solution  of  Ked  Prussiate  of  Potash,’’  B.  P. 

Hydrofluoric  Acid  (HF)  and  Other  Fluorides. — 
Molecular  weight  of  HF,  20.  The  chief  use  of  hydrofluoric 
acid  is  in  the  etching  on  glass.  The  operation,  pertormed 
on  the  small  scale,  also  constitutes  the  best  test  for 
fluorine,  the  elementary  radical  of  all  fluorides. 

Process  and  Test, — Warm  any  odd  piece  of  window- 
glass,  having  an  inch  or  two  of  surface,  until  a piece  of 
beeswax  rubbed  on  one  side  yields  a thin  oilj^  film.  Wlien 
cool  make  a cross,  letter,  or  other  mark  on  the  glass  by 
pressing  a pointed  piece  of  wood,  a‘  penknife,  or  file, 
through  the  wax.  Place  a few  grains  of  powdered  fluor 
spar,  the  commonest  natural  fluoride,  in  a porcelain  crucible 
(or  a lead  cup),  add  a drop  or  two  of  sulphuric  acid,  cover 


HYPOPHOSPHOROUS  ACID. 


305 


the  crucible  with  the  prepared  glass,  waxed  side  down- 
wards, and  gently  warm  the  bottom  of  the  crucible  in  a 
fume-chamber  or  in  the  open  air,  in  such  a way  as  not  to 
melt  the  wax.  After  a few  minutes  remove  the  glass,  wash 
the  waxed  side  by  pouring  water  over  it,  scrape  off  most  of 
the  wax,  then  warm  the  glass^  and  wipe  off  the  remainder  ; 
the  marks  made  through  the  wax  will  be  found  to  be  per- 
manently etched  on  the  glass;  the  acid  has  eaten  into  or 
etched  (ft’om  the  German  dtzen^  to  corrode)  the  glass. 

In  the  above  operation  the  fluoride  of  calcium  and  sulphuric  acid 
yield  hydrofluoric  acid,  thus  : — 

-CaF2  + H^SO,  = CaSO,  + 2HF. 

The  hydrofluoric  acid  gas  and  the  silica  of  the  glass  then  yield 
gaseous  fluoride  of  silicon  (SiF^),  which  escapes,  and  water,  thus : — 

4HF  + SiO^  = 2H2O  -F  SiF^. 

The  silica  being  removed  from  the  glass,  leaves  furrows  or  etched 
portions. 

Note. — In  the  experiment  just  described,  the  liberated  hydrofluoric 
acid  also  attacks  the  siliceous  glazing  of  the  porcelain  crucible ; so 
that  in  important  cases,  where  search  is  made  for  very  small  quanti- 
ties of  fluorine,  vessels  of  platinum  or  lead  must  be  employed. 

Uses. — The  aqueous  solution  of  hydrofluoric  acid  used  by  etchers, 
and  commonly  termed  simply  hydrofluoric  acid,  or  fluoric  acid,  is 
prepared  in  leaden  stills  and  receivers,  and  kept  in  leaden  or  gutta- 
percha bottles.  Except  these  materials,  as  well  as  platinum  and 
fluor  spar,  hydrofluoric  acid  rapidly  attacks  any  substance  of  which 
bottles  and  basins  are  usually  made.  It  quickly  cauterizes  the  skin, 
producing  a painful  slow-healing  sore. 

Quantivalence. — The  atom  of  fluorine,  like  that  of  chlorine,  bro- 
mine, or  iodine,  is  univalent  (F').  The  great  analogy  existing  be- 
tween these  radicals  extends  to  their  compounds. 

Fluorine  is  said  to  be  a colorless  gas ; but,  from  the  avidity  with 
which  it  combines  with  all  elements  (except  oxygen),  it  is  so  difficult 
of  isolation  as  hitherto  to  preclude  satisfactory  study  of  its  physical 
properties. 

Hypophosphorous  Acid  (HaPO.^,  or  HPH2O2)  and  other 
Hypophosphites. — Boil  together,  in  a fume-chamber,  a 
grain  or  two  of  phosphorus,  a few  grains  of  slaked  lime, 
and  about  a quarter  of  an  ounce  of  water  until  phospho- 
retted  hydrogen,  a spontaneously  inflammable,  badly  smell- 
ing gas,  ceases  to  be  evolved.  The  mixture.  Altered,  yields 
solution  of  hypophosphite  of  calcium  (Ca2PHaO 

Pg  _F  6H,0  + SCaH^Oa  = 3(Ca2PH20,)  + 2PH3. 

The  solution,  when  concentrated  by  evaporation,  has  been  known 
to  explode,  probably  from  formation  of  phosphoretted  hydrogen. 

2G* 


306  SALTS  OF  RARER  ACIDULOUS  RADICALS. 


This  may  be  prevented,  it  is  said,  by  evaporating  at  a low  tempera- 
ture, especially  towards  the  close  of  the  operation  ; or  by  adding 
alcohol,  which  decomposes  any  traces  of  liquid  phosphoretted  hydro- 
gen (PH,)  or  solid  phosphoretted  hydrogen  (P2H)  which  possibly 
may  be  present,  and  to  which  it  is  conceivable  explosion  may  be  due. 

Phosphoretted  hydrogen  (PH3). — The  above  reaction  is  also  that 
by  which  phosphoretted  hydrogen,  the  third  hydride  of  phosphorus, 
may  be  prepared.  If  the  gas  is  to  be  collected,  the  phosphorus  and 
water  may  first  be  boiled  in  a flask  until  spontaneously  a jet  of  phos- 
phorus vapor  escapes,  with  steam,  from  the  end  of  the  attached  de- 
livery-tube. Strong  solution  of  caustic  potash  or  soda  is  next  very 
gradually  poured  into  the  flask  through  a funnel  tube  previously  fitted 
into  the  cork,  the  liquid  being  kept  boiling.  Phosphoretted  hydro- 
gen is  then  evolved,  and  if  the  delivery-tube  dip  under  water  may  be 
collected,  or  allowed  to  slowly  pass  up  through  the  water  bubble  by 
bubble  so  as  to  form  the  peculiar  rings  of  smoke  (phosphoric  anhy- 
dride) characteristic  of  the  experiment. 

Hypoyhosphite  of  calcium  may  be  obtained  in  crystals  [Calcii 
Hypophosphis,  U.  S.  P.) ; but  the  solution  is  usually  at  once  evapo- 
rated to  dryness,  a white  pulverulent  salt  being  obtained.  The 
hypophosphites  of  Potassium  and  Sodium  [Potassii  Hypophosphis^ 
U.  S.  P.,  and  Sodii  Hypophosphis,  U.  S.  P.)  may  be  obtained  in  the 
same  way  from  their  hydrates,  and  many  other  hypophosphites  simi- 
larly from  other  hydrates,  or  by  double  decomposition  of  the  calcium 
salt  and  carbonates.  Hypophosphorous  acid,  the  hydrogen  hypo-  ; 
phosphite,  may  be  prepared  by  decomposing  the  barium  salt  with  I 
sulphuric  acid  or  the  calcium  salt  by  oxalic  acid  ; hypophosphite  of 
quinine  by  dissolving  the  alkaloid  in  hypophosphorous  acid,  or  by 
decomposing  sulphate  of  quinine  by  hypophosphite  of  barium.  Hypo- 
phosphite  of  Iron  [Ferri  Hypophosphis,  U.  S.  P.)  may  be  obtained 
by  dissolving  ferric  hydrate  in  cold  aqueous  hypophosphorous  acid  and 
evaporating  the  solution.  The  hypophosphites  are  often  used  in  j 
medicine  in  the  form  of  syrups.  The  term  hypophosphite  is  in  allu-  ■ 
sion  to  the  smaller  amount  [vrco,  hupo,  under  or  deficiency)  of  oxygen  i 
in  these  compounds  (R'3P02)  than  in  the  phosphites  (R3PO3),  a class  I 
of  salts  having  again  less  oxygen  in  their  molecules  than  exists  in  ! 
those  of  the  phosphates  (R3POJ.  The  prefix has  similar  signi-  j 
ficance  in  such  words  as  hyposulphite  and  hypochlorite.  I 

Tests. — To  a portion  of  the  above  solution  af  hy^poplios-  I 
pliite  of  calcium  add  solution  of  chloride  of  barium,  clilo-  i 
ride  of  calcium,  or  acetate  of  lead  ; in  neither  case  is  a i 
precipitate  obtained,  whereas  soluble  phosphates  and  phos- 
phites yield  white  precipitates  of  phosphate  or  phosphite  • 
of  barium,  calcium,  or  lead.  To  other  portions  add  solu-  : 
tions  of  nitrate  of  silver  and  mercuric  chloride  ; the  resi)ec- 
tive  metals  are  precipitated  as  by  phosphites.  To  another 
small  j^ortion  add  zinc  and  dilute  sulphuric  acid  ; hydrogen 
and  phosphoretted  hydrogen  are  evolved  as  from  phosphites.  ; 
To  another  portion  add  sufficient  oxalic  acid  to  remove  the 
calcium;  filter;  to  the  solution  of  hypophosphorous  acid 


HYPOSULPHUROUS  ACID. 


SOY 


add  solution  of  sulphate  of  copper  and  slowly  warm  the 
mixture ; solid  brown  hydrate  of  copper  is  precipitated  : 
increase  the  heat  to  the  boiling-point;  hydrogen  is  evolved 
and  metallic  copper  set  free.  Heat  a small  quantity  of  a 
solid  hypophosphite  on  the  end  of  a spatula  in  a flame ; 
it  splits  up  into  pyrophosphate,  phosphoretted  hydrogen, 
and  water,  burning  with  a phosphorescent  light. 

2(Ca2PH,0,)  = Ca,P,0,  -f  2PH3  +H,0. 

Hyposulphurous  Acid  (H^S^Og)  and  other  Hyposul- 
phites.— The  only  hyposulphite  of  much  interest  in  phar- 
macy is  the  sodium  salt  (Hyposulphite  of  Soda,  B.  P.,  Sodii 
Eyposulphis,  H.  S.  P.)  (Na^S.Pg,  bUfi). 

Process. — Heat  together  gentljq  or  set  aside  in  a warm 
place,  a mixture  of  solution  of  sulphite  of  sodium  (Na.^SOg), 
and  a little  powdered  sulphur;  combination  slowly  takes 
place,  and  hyposulphite  of  sodium  is  formed.  The  solu- 
tion, Altered  from  excess  of  sulphur,  readily  yields  crystals. 
[The  solution.of  sulphite  of  sodium  may  be  made  by  satu- 
rating a solution  of  soda  with  sulphurous  acid  gas.] 

Use  of  hyposulphite  of  sodium  in  quantitative  analysis. — 
In  the  British  Pharmacopoeia  hyposuli)hite  of  sodium  is 
given  as  a reagent  for  the  quantitative  estimation  of  free 
iodine  in  volumetric  analysis.  To  a few  drops  of  iodine- 
water  add  cold  mucilage  of  starch;  a deep-blue  color 
(starch  iodide)  is  produced.  To  the  product  add  solution 
of  hyposulphite  of  sodium  until  the  blue  color  just  disap- 
pears. This  absorption  of  iodine  is  sufliciently  deflnite  and 
delicate  to  admit  of  application  for  quantitative  purposes. 
II  depends  on  the  combination  of  the  iodine  with  half  of  the 
sodium  in  two  molecules  of  the  hyposulphite,  the  hy^osul- 
phurous  radicals  of  the  two  molecules  apparently  coalescing 
to  form  a new  radical,  the  tetrathionic  (from  rirpa?,  tetras^ 
four,  and  theion.^  sulphur),  tetrathionate  (Na^S^O,.)  and 
iodide  of  sodium  being  formed. 

Sulphur  Oxyacids. — It  will  be  as  well  here  to  give  the  formulae 
of  other  oxyacids  of  sulphur,  forming  with  the  four  already  mentioned 
a series  that  is  as  useful  as  the  series  of  compounds  of  nitrogen  and 
oxygen  in  illustrating  the  soundness  of  Dalton’s  atomic  theory  (p.  43). 


Hydrosulphurous  Acid  . . . 

. . . H,SO, 

Sulphurous  Acid 

. . . H.SOg 

Sulphuric  Acid 

. . . H,SO, 

Hyposulphurous  Acid  . . . 

. . . H.S^O, 

Dithionic  Acid 

. . . TI.,S,Og 

Trithionic  Acid 

Tetrathionic  Acid  

Pentathionic  Acid 

■ . . 

308  SALTS  OF  RARER  ACIDULOUS  RADICALS. 

Use  of  Hypo'^^  in  Photography, — The  sodium  hyposul- 
phite is  largelj"  used  in  photography  to  dissolve  chloride, 
bromide,  or  iodide  of  silver  off  plates  which  have  been  ex- 
posed in  the  camera.  Prepare  a little  chloride  of  silver  by 
adding  a chloride  (chloride  of  sodium)  to  a few  drops  of 
solution  of  nitrate  of  silver.  Collect  the  precipitated  chlo- 
ride on  a filter,  wash,  and  add  a few  drops  of  solution  of 
hyposulphite  of  sodium;  the  silver  salt  is  dissolved,  solu- 
tion of  double  hyposulphite  of  sodium  and  silver  being 
formed.  The  solution  of  this  double  hyposulphite  has  a 
remarkabl}^  sweet  taste,  sweeter  than  syrup.  The  double 
hyposulphite  of  sodium  and  gold  is  employed  for  giving  a 
pleasant  tint  to  photographic  prints. 

Test, — To  solution  of  a hyposulphite  add  a few  drops  of 
dilute  sulphuric  or  other  acid  ; hyposulphurous  acid  is  set 
free,  but  at  once  begins  to  decompose  into  sulphurous  acid, 
recognized  by  its  odor,  and  free  sulphur  (2H.^S^03= 
2H2SO3  + S2).  This  reaction  constitutes  the  best  test  for 
hyposulphites.  Another  good  test  of  a soluble  simple 
hyposulphite  is  its  power  of  dissolving  chloride  of  silver 
with  production  of  a sweet  solution. 


QUESTIONS  AND  EXERCISES. 

588.  Give  the  formula  of  ferrocyanide  of  potassium. 

589.  What  is  the  supposed  constitution  of  ferrocyanide  of  potas- 
sium ? 

590.  Enumerate  the  tests  for  ferrocyanogen. 

591.  What  are  the  respective  reactions  of  ferrocyanide  of  potas- 
sium with  strong  and  weak  sulphuric  acid  ? 

592.  Mention  and  explain  a common  source  of  carbonic  oxide  in 
households  ? 

593.  Write  equations  or  diagrams  illustrative  of  the  changes 
effected  on  ferrocyanide  of  potassium  during  its  conversion  into  fer- 
ridcyanide. 

594.  By  what  reactions  may  the  presence  of  a ferridcyanide  in  a 
solution  be  demonstrated  ? 

595.  State  the  difference  between  Prussian  blue  and  Turnbull’s 
blue. 

596.  Describe  the  source,  mode  of  preparation,  chief  use  of,  and 
test  for  hydrofluoric  acid. 

597.  Illustrate  by  a diagram  the  preparation  and  composition  of 
hyposulphite  of  sodium. 

598.  Mention  the  uses  and  characteristic  reactions  of  hyposulphite 
of  sodium. 

599.  Give  the  names  and  formuhe  of  eight  acids,  each  containing 
hydrogen,  sulphur,  and  oxygen. 


LACTATES. 


309 


Lactic  Acid  (HgCaH^Og)  and  other  Lactates. — When  milk 
turns  sour  its  sugar  has  become  converted  into  an  acid  appropriately 
termed  lactic  (Zac,  lactis).  Other  saccharine  and  amylaceous  sub- 
stances also  by  fermentation  yield  lactic  acid.  Neither  the  hydrogen 
lactate  (lactic  acid)  nor  other  lactates  are  much  used  in  England, 
but  the  former  is  official  in  America  [Acidum  Lacticum,  U.  S.  P.). 

Process, — Lactate  of  calcium  and  lactic  acid  may  be  pre- 
pared as  follows : Mix  together  eight  parts  of  sugar,  one  of 
common  cheese,  three  of  chalk,  and  fifty  of  water,  and  set 
aside  in  a warm  place  (about  80°  F.)  for  two  or  three 
weeks  ; a mass  of  small  crystals  of  lactate  of  calcium  re- 
sults. Kemove  these,  recrystallize  from  hot  water,  decom- 
pose by  sulphuric  acid,  avoiding  excess,  digest  in  alcohol, 
filter  off  the  sulphate  of  calcium,  evaporate  the  clear  solu- 
tion to  a syrup  ; this  residue  is  lactic  acid  ; sp.  gr.  1.2 12. 

Lactate  of  Iron  {Ferri  Lactas,^  U.  S.  P.)  is  made  by  di- 
gesting iron  filings  in  warm  diluted  lactic  acid  (1  acid  to 
16  water)  till  effervescence  of  hydrogen  ceases,  filtering  and 
setting  aside  to  cool  and  crystallize.  The  crystals  are  col- 
lected, washed  with  alcohol,  and  dried.  This  ferrous  lac- 
tate occurs  in  greenish-white  crystalline  crusts  or  grains, 
of  a mild,  sweetish,  ferruginous  taste,  soluble  in  forty-eight 
parts  of  cold,  and  twelve  of  boiling  water,  but  insoluble  in 
alcohol.  Exposed  to  heat  it  froths  up,  gives  out  thick, 
white,  acid  fumes,  and  becomes  black  ; sesquioxide  of  iron 
being  left.  If  it  be  boiled  for  fifteen  minutes  with  nitric 
acid  of  the  specific  gravity  1.20,  a white,  granular  deposit 
of  mucic  acid  will  occur  on  the  cooling  of  the  liquid. 

Test. — No  single  reaction  of  lactic  acid  is  sufficiently 
distinctive  to  form  a test.  The  crystalline  form  of  the 
lactate  of  calcium,  as  seen  by  the  microscope,  is  charac- 
teristic. The  production  of  this  salt,  and  the  isolation  of 
the  syrupy  acid  itself,  are  the  only  means,  short  of  quanti- 
tative analysis,  on  which  reliance  can  be  placed. 

A variety  of  lactic  acid  has  been  obtained  from  the  juice 
of  fish ; it  is  termed  sarcolactic  acid  (from  od/jl,  gen.  aapxoj, 
flesh). 

Malic  Acid  (1130^11305)  and  other  Malates  (from 
malum^  an  apple). — The  juice  of  unripe  apples,  goose- 
berries, currants,  rhubarb  stalks,  etc.,  contains  malic  acid 
and  malate  of  potassium.  When  isolated  it  occurs  in 
deliquescent  prismatic  crystals. 

Tests. — Malate  of  calcium  (CaHC^H305)  is  soluble  in 
water ; hence  the  aqueous  solution  of  malic  acid  or  other 
malate  is  not  precipitated  by  lime-water  or  chloride  of  cal- 


310  SALTS  OF  RARER  ACIDULOUS  RADICALS. 

cium  ; but  on  adding  spirit  of  wine  a white  precipitate  falls, 
owing  to  the  insolubility  of  the  calcium  malate  in  alcohol. 
Malates  are  precipitated  by  lead-salts;  on  warming  the 
malate  of  lead  with  acetic  acid  it  dissolves,  separating  out 
in  acicular  crystals  on  cooling.  If  the  mixture  be  heated 
without  acid  the  malate  of  lead  agglutinates  and  fuses. 

Hot  strong  sulphuric  acid  chars  malic  acid  far  less  readily  than  it 
does  nearly  all  other  organic  acids. 

Malic  acid  is  one  of  the  chief  products  of  the  action  of  nitrous 
acid  on  asparagin  ( 04118^.^03, ^ crystalline  body  extracted  from 
asparagus  and  marshmallow  [Althea,  XJ.  S.  P.). 

Meconic  Acid  (H3C-HO7).  Opium  contains  meconic 
acid  (from  mekon^  a poppy)  partially  combined  with 

morphia.  To  concentrated  infusion  of  opium,  nearly  neu- 
tralized by  ammonia,  add  solution  of  chloride  of  calcium, 
meconate  of  calcium  is  precipitated.  Wash  the  precipitate, 
place  it  in  a small  quantity  of  hot  water,  and  add  a little 
hydrochloric  acid ; the  clear  liquid  (filtered,  if  necessary) 
deposits  scales  of  meconic  acid  on  cooling. 

Test — To  solution  of  meconic  acid  or  other  meconate, 
or  to  infusion  of  opium,  add  a neutral  solution  of  ferric 
chloride ; a red  solution  of  meconate  of  iron  is  produced.  | 
To  a portion  of  the  mixture  add  solution  of  corrosive  sub- 
limate; the  color  is  not  destroyed;  to  another  portion  add 
hydrochloric  acid;  the  color  is  discharged.  (These  reagents 
act  on  sulphocyanate  of  iron,  which  is  of  similar  tint,  in 
exactly  the  opposite  manner.) 

The  normal  mecoiiates  of  potassium,  sodium,  and  ammonium  are 
soluble  in  water,  the  acid  meconates  very  slightly  soluble,  the  meco- 
nates  of  barium,  calcium,  lead,  copper,  and  silver  insoluble  in  water 
but  soluble  in  acetic  acid. 

Metaphosphoric  Acid  (HPO3)  and  other  Metaphos- 
phates.— Prepare  phosphoric  anhydride  (P2O5)  by  burning 
a small  piece  of  phosphorus  in  a porcelain  crucible  placed 
on  a plate  and  covered  by  an  inverted  test-glass,  tumbler, 
half-pint  measure-glass,  or  some  such  vessel.  After  wait-  ! 
ing  a few  minutes  for  the  phosphoric  anhydride  to  fall,  i 
pour  a little  water  on  the  plate  and  filter  the  liquid ; the 
product  is  solution  of  metaphosphoric  acid  (from  ^tra,  1 
meta^  a preposition  denoting  change). 

P,0,  -f  H,0  = 2HPO3. 

Tests, — To  solution  of  metaphosphoric  acid  add  ammo- 
nio-nitrate  of  silver,  or  to  a neutral  raetaphosphate  add 


NITRITES. 


811 


solution  of  nitrate  of  silver ; a white  precipitate  (AgPOg) 
is  obtained.  This  reaction  sufficiently  distinguishes  meta- 
phosphates  from  the  ordinary  phosphates  or  orthophos- 
phates (from  6p06?  orthos^  straight),  as  the  common  phos- 
phates may,  for  distinction,  be  termed  (which  give,  it  will 
be  remembered,  a yellow  precipitate  with  nitrate  of  silver). 
Another  variety  of  phosphates  shortly  to  be  considered, 
the  pyrophosphates,  also  give  a white  precipitate  with 
nitrate  of  silver.  To  the  solution  of  metaphosphoric  acid 
obtained  as  above  or  by  the  action  of  acetic  acid  on  a 
metaphosphate,  add  an  aqueous  solution  of  white  of  egg ; 
coagulation  of  the  albumen  ensues.  Neither  orthophos- 
phoric  nor  pyrophosphoric  acid  coagulates  albumen.  Boil 
the  aqueous  solution  of  metaphosphoric  acid  for  some  time  ; 
on  testing  the  solution  the  acid  will  be  found  to  have  been 
converted  into  orthophosphoric  acid  : 

HPO3  -f  H,0  = H3PO,. 

The  ordinary  medicinal  phosphoric  acid  is  made  from 
phosphorus  and  nitric  acid,  the  liquid  being  evaporated  to 
a syrupy  consistence  to  remove  the  last  traces  of  nitric 
acid.  It  may  contain  pyrophosphoric  and  metaphosphoric 
acids,  if  the  heat  employed  be  high  enough  to  remove  the 
elements  of  water: — 

JE^O,  — H,0  = HPO3. 

On  redilution  the  metaphosphoric  acid  only  slowly  reab- 
sorbs water.  If,  therefore,  on  testing,  metaphosphoric  be 
found  to  be  present,  the  solution  should  be  boiled  until 
conversion  to  orthophosphoric  acid  has  occurred. 

Nitrous  Acid  (HNOJ  and  other  Nitrites — Strongly 
heat  a fragment  of  nitrate  of  potassium  or  of  sodium  on  a 
piece  of  platinum  foil ; oxygen  is  evolved  and  nitrite  of 
potassium  remains. 

Test, — Dissolve  the  residue  in  water,  add  a few  drops  of 
dilute  sulphuric  acid,  then  a little  weak  solution  of  iodide 
of  potassium,  and,  lastly,  some  mucilage  of  starch  ; the 
deep-blue  compound  of  iodine  and  starch  is  at  once  pro- 
duced. Repeat  this  experiment,  using  nitrate  of  potassium 
instead  of  nitrite ; no  blue  color  is  produced. 

2HI  + 2HNO3  = 2H,0  + 2NO  + I,. 

Test  for  Nitrites  in  Water. — This  liberation  of  iodine  by  nitrites 
and  not  by  nitrates  is  a reaction  of  considerable  value  in  searching 
for  nitrites  in  ordinary  drinking-waters,  the  occurrence  of  such  salts 


312  SALTS  OF  RARER  ACIDULOUS  RADICALS. 


being  held  to  indicate  the  presence  of  nitrogenous  organic  matter  in 
a state  of  oxidation  or  decay.  The  sulphuric  acid  used  in  the  ope- 
ration  must  be  pure,  and  the  iodide  of  potassium  free  from  iodate. 

Commercial  Nitrous  Acid. — The  liquid  commonly  termed  in 
pharmacy  nitrous  acid  is  simply  nitric  acid  impure  from  the  presence 
of  nitrous  acid. 

The  only  nitrite  used  in  medicine  is  a nitrite  of  an  organic  basy- 
lous  radical,  ethyl;  nitrite  of  ethyl  (C2H5NO2),  or  nitrous  ether,  is 
the  chief  constituent  of  “ sioeet  spirit  of  nitre''  [S'piritus  JStheris 
Nitrosi,  B.  P.  and  U.  S.  P. : vide  Index). 

Phosphorous  Acid  (H3PO3,  or  H2PIIO3). — It  is  necessary  to 
notice  this  compound  in  order  that  the  reader  may  have  brought 
before  him  the  three  acids  of  phosphorus,  namely,  phosphoric  acid 
(H3PO4),  phosphorous  acid  (H2PIIO3),  and  hypophosphorous  acid 
(IIPH2O2) : it  will  be  noticed  that  in  composition  they  differ  from 
each  other  simply  in  the  proportion  of  oxygen,  the  molecules  con- 
taining four,  three,  and  two  atoms  respectively.  In  constitution 
they  differ  by  the  hypothetical  phosphoric  radical  or  grouping  being  1 
trivalent,  the  phosphorous  bivalent,  and  the  hypophosphorous  univa- 
lent. These  three  acids  and  corresponding  salts  must  not  be  con-  j 
founded  with  pyrophosphoric  and  metaphosphoric  acids  and  salts ; the . I 
former  are  acids  of  phosphorus ; the  latter,  varieties  of  phosphoric  I 
acid:  the  former,  in  composition,  differ  from  each  other  in  the  propor- 
tion of  oxygen  they  contain  ; the  latter,  by  the  elements  of  water  : — 

Acids  of  Phosphorus.  Varieties  of  Phosphoric  Acid. 

H3PO4  phosphoric  acid.  H3PO4  (ortho) phosphoric  acid. 

H2PHO3  phosphorous  acid.  H^P207  pyrophosphoric  acid. 

IIPII2O2  hypophosphorous  acid.  IIPO3  metaphosphoric  acid. 

When  hypophosphorous  acid  is  exposed  to  the  air,  oxygen  is  absorbed 
and  phosphorous  acid  results ; by  prolonged  exposure  more  oxygen 
is  absorbed  and  phosphoric  acid  is  obtained.  When  phosphoric  acid, 
or  rather,  for  distinction,  orthophosphoric  acid  is  heated,  every  two 
molecules  yield  the  elements  of  a molecule  of  water,  and  pyrophos- 
phoric acid  results ; by  prolonged  exposure  to  heat  more  water  is 
evolved,  and  metaphosphoric  acid  is  obtained.  These  differences 
will  be  further  evident  if  the  formulae  be  written  empirically,  nearly 
all  being  doubled,  thus  : — 


hypophosphorous  acid. 
IIgP206  phosphorous  acid. 

TT  P O I phosphoric  acid,  or 
® 2 8 1 orthophosphoric  acid. 
H4P2O7  pyrophosphoric  acid. 

rotJtaphosphoric  acid. 


Or  thus : — 


phosphoric  acid 


H«P,0«. 


6^  2^8* 


pyrophosphoric  acid 

u.PA- 


metaphosphoric  acid 


HgPA. 


gL 


H.P.Og. 


PYROPHOSPHORIC  ACID. 


313 


From  the  central  compound,  phosphoric  acid,  the  acids  of  phosphorus 
differ  by  regularly  diminishing  proportions  of  the  element  oxygen 
(see  previous  page),  the  varieties  of  phosphoric  acid  by  regularly 
diminishing  proportions  of  the  elements  of  water. 

Pi'epare  phosphorous  acid  by  exposing  a moist  stick  of 
phosphorus  to  the  air ; a thin  stream  of  heavy  white  vapor 
falls,  which  is  the  acid  in  question.  The  best  method  of 
collection  is  to  place  the  stick  in  an  old  test-tube  having  a 
hole  in  the  bottom,  to  support  this  tube  by  a funnel  or 
otherwise,  the  neck  of  the  funnel  being  supported  in  a 
bottle,  test-glass,  or  tube,  at  the  bottom  of  wdiich  is  a little 
water.  Having  collected  some  phosphorous  acid  in  this 
wa\q  apply  the  various  tests  already  alluded  to  under  Hypo- 
phosphorous  Acid^  first  carefully  neutralizing  the  phospho- 
rous acid  b}^  an  alkali.  The  means  by  which  the  A^arieties 
of  phosphoric  acid  are  distinguished  have  been  given  under 
Metaphosphoric  Acid. 

Other  soluble  phosphites  are  prepared  by  neutralizing 
phosphorous  acid  with  alkalies, and  the  insoluble  phosphites 
by  double  decomposition. 

Pyrogallig  Acid. — See  Tannic  Acid. 

Pyrophosphoric  Acid  (H^P20.)  and  other  Pyrophos- 
phates.— Heat  ordinary  phosphate  of  sodium  (Na^HPO^, 
I2H2O)  in  a crucible ; water  of  crystallization  is  first 
evolved,  and  diy  phosphate  (Na2HPOJ  remains.  Continue 
the  heat  to  redness ; two  molecules  of  the  salt  yield  one 
molecule  of  water,  and  a salt  having  new  properties  is 
obtained : — 

2Na2HPO,  — H2O  = Na,P20,. 

It  is  termed  pyrophosphate  of  sodium,  in  allusion  to  its  origin 
(nit’p,  pur,  fire).  Other  pyrophosphates  are  produced  in  a similar 
way,  or  by  double  decomposition  and  precipitation,  or  by  neutraliz- 
ing pyrophosphoric  acid  by  an  oxide,  hydrate,  or  carbonate.  Possi- 
bly the  pyrophosphates  are  only  compounds  or  orthophosphates  with 
metaphosphates  : — 

Na^P207  = Na3PO^,  NaPOg. 

Tests. — To  solution  of  a pyrophosphate  add  solution  of 
nitrate  of  silver  ; white  pyrophosphate  of  silver  (Ag^P207) 
falls  as  a dense  white  powder,  differing  much  in  appearance 
from  the  white  gelatinous  metaphosphate  of  silver  or  the 
yellow  orthophosphate.  To  pyrophosphoric  acid,  or  to  a 
pyrophosphate  mixed  with  acetic  acid,  add  an  aqueous 
solution  of  albumen  (white  of  egg)  ; no  precipitate  occurs. 
Metaphosphoric  acid,  it  will  be  remembered,  gives  a white 
precipitate  with  albumen. 

27 


314  SALTS  OF  RARER  ACIDULOUS  RADICALS. 


QUESTIONS  AND  EXERCISES. 

600.  What  are  the  sources  of  lactic  acid  ? 

601.  How  is  lactic  acid  usually  prepared  ? 

602.  Name  some  of  the  plants  in  which  malic  acid  is  found. 

603.  AVhence  is  meconic  acid  derived  ? 

604.  By  what  process  may  meconic  acid  be  isolated  ? 

605.  Which  is  the  best  test  for  the  meconic  radical  ? 

606.  Distinguish  meconates  from  sulphocyanates. 

607.  Give  the  mode  of  manufacture  of  hypophosphites. 

608.  How  is  phosphoretted  hydrogen  prepared  ? 

609.  By  what  ready  method  may  metaphosphoric  acid  be  obtained 
for  experimental  purposes  ? 

610.  Name  the  tests  for  metaphosphates. 

611.  How  may  meta- or  pyro-phosphoric  acid  be  converted  into 
orthophosphoric  acid  ? 

612.  Describe  the  preparation  of  phosphorous  acid. 

613.  State  the  relations  which  the  acids  of  phosphorus  bear  to 
each  other. 

614.  How  are  pyrophosphates  prepared  ? 

615.  Offer  two  views  of  the  constitution  of  pyrophosphates. 

616.  Define,  by  formulae,  metaphosphates,  pyrophosphates,  ortho- 
phosphates, phosphites,  and  hypophosphites. 

617.  Mention  the  tests  by  wdiich  meta-,  pyro-,  and  orthophosphates 
are  analytically  distinguished. 

618.  Name  the  reactions  by  which  hyposulphites  and  phosphites 
are  detected. 

Silicic  Acid  (H^SiOJ  and  other  Silicates. — Silicates  of  various 
kinds  are  among  the  commonest  of  minerals.  The  various  days  are 
aluminium  silicates ; meerschaum  is  an  acid  silicate  of  magnesium ; 
the  ordinary  sandstones  are  chiefly  silica;  sand,  flint,  quartz,  agate, 
chalcedony,  and  opal  are  silicic  anhydride  or  silica  (SiO.J.  Asbestos 
or  amianth  is  a fibrous  silicate  of  calcium  and  magnesium.  Artifi- 
cial silicates  are  familiar  under  the  forms  of  glass  and  earthenware. 
Common  English  wdndow-glass  is  usually  silicate  of  calcium,  sodium, 
and  aluminium ; French  glass,  silicate  of  calcium  and  sodium ; 
Bohemian,  chiefly  silicate  of  potassium  and  calcium ; English  flint- 
or  crystal-glass  for  ornamental,  table,  and  optical  purposes,  is  mainly 
silicate  of  potassium  and  lead.  Earthenware  is  mostly  silicate  of 
aluminium,  (clay),  with  more  or  less  of  silicate  of  calcium,  sodium, 
and  potassium,  and,  in  the  commoner  forms,  iron.  The  various  kinds 
of  porcelain  (China,  Sevres,  Meissen,  Berlin,  English),  Wedgwood- 
ware,  and  stoneware  are  varieties  of  earthenware.  Crucibles,  bricks, 
and  tiles  are  clay-silicates.  Mortar  is  essentially  silicate  of  calcium. 
Portland,  Roman,  and  other  hydraulic  cements  are  silicates  of  cal- 
cium with  more  or  less  silicate  of  aluminium. 

Alix  together  a few  grains  of  powdered  flint  or  sand  with  ^ 
about  live  or  six  times  its  rveight  of  carbonate  of  sodium  i 


SUCCINIC  ACID. 


315 


and  an  equal  quantity  of  carbonate  of  potassium,  and  fuse 
a little  of  the  mixture  on  platinum-foil  in  the  blowpipe- 
flame;  the-product  is  a kind  of  soluble  glass.  Boil  the  foil 
in  water  for  a few  minutes,  filter ; to  a portion  add  excess 
of  hjTlrochloric  acid,  evaporate  the  solution  to  dryness, 
and  again  boil  the  residue  in  water  and  acid;  oxide  of 
silicon,  or  silica,^  (Si02)  remains  as  a light,  flaky,  insoluble 
powder. 

The  soluble  glass  or  glass  liquor  of  trade  commonly  contains  10 
or  12  per  cent,  of  soda  (NallO)  to  20  or  25  per  cent,  of  silica  (SiOg). 

The  foregoing  operation  constitutes  the  test  for  silicates.  By  fusion 
with  alkali  the  silicate  is  decomposed,  and  a soluble  alkaline  silicate 
formed.  On  addition  of  acid,  silicic  acid  (H^SiO^)  is  set  free,  but 
remains  in  solution  if  sufficient  water  is  present.  The  heat  subse- 
quently applied  eliminates  water  and  reduces  the  silicic  acid  to  silica 
(SiO.,),  which  is  insoluble  in  water  or  acid.  By  the  addition  of  hydro- 
chloric acid  to  soluble  glass,  and  removal  of  the  resulting  alkaline 
chloride  and  excess  of  hydrochloric  acid  by  dialysis  (a  process  to  be 
subsequently  described),  a pure  aqueous  solution  of  silicic  acid  may 
be  obtained  ; it  readily  changes  into  a gelatinous  mass  of  silicic  acid. 
Possibly  some  of  the  natural  crystallized  varieties  of  silica  may  have 
been  obtained  from  the  silica  contained  in  such  an  aqueous  solution, 
nearly  all  waters  yielding  a small  quantity  of  silica  when  treated  as 
above  described. 

A variety  of  silicic  acid  (H2Si03)  sometimes  termed  dibasic,  to 
distinguish  it  from  the  normal  or  tetrabasic  acid  (H^SiO^),  results 
when  the  aqueous  solution  of  the  latter  is  evaporated  in  vacuo, 

Siliciuretted  hydrogen,  or  hydride  of  silicon  (SiH^),  is  a sponta- 
neously inflammable  gas  formed  on  treating  silicide  of  magnesium 
with  hydrochloric  acid.  It  is  the  analogue  of  light  carburetted  hydro- 
gen (CH^).  A liquid  chloride  of  silicon  (SiCl^)  and  a gaseous  fluoride 
(SiF^)  also  exist. 

Succinic  Acid  (H2C4H4O4). — Amber  [Succinum)  is  a peculiar 
resin  usually  occurring  in  association  with  coal  and  lignite.  From 
the  fact  that  fragments  of  coniferous  fruit  are  frequently  found  in 
amber,  and  impressions  of  bark  on  its  surface,  it  is  considered  to  have 
been  an  exudation  from  a species  of  Pinus  now  probably  extinct. 
Heated  in  a retort,  amber  yields,  first,  a sour  aqueous  liquid  contain- 
ing acetic  acid  and  another  characteristic  body  appropriately  termed 
succinic  acid;  second,  a volatile  liquid  known  as  oil  of  amber 
(Oleum  Succini  Rectificatum,  U.  S.  P.)  resembling  the  oil  yielded 
by  most  resinous  substances  under  similar  circumstances  ; and,  third, 
a pitchy  residue  allied  ^o  asphalt.  The  succinic  acid  is  a normal 
constituent  of  the  amber,  the  acetic  acid  is  produced  during  distilla- 
tion. Succinic  acid  has  also  been  found  in  wormwood,  in  several 
pine-resins,  and  in  certain  animal  fluids,  such  as  those  of  hydatid 
cysts  and  hydrocele.  It  may  be  obtained  artificially  from  butyric, 
stearic,  or  margaric  acid  by  oxidation.  Tartaric,  malic,  and  succinic 
acids  are  also  convertible  the  one  into  the  other. 


316  SALTS  OF  RARER  ACIDULOUS  RADICALS. 


The  succinates  are  normal  (^'2^411404)  and  acid  (E'HC^H^O  J;  a 
double  succinate  of  potassium  and  hydrogen  (KHC4H404,H2C4H404, 
H2O),  analogous  to  the  superacid  oxalate,  salt  of  sorrel^  also  exists. 

Soluble  succinates  give  a bulky  brown  precipitate  with 
neutral  ferric  chloride,  only"  less  voluminous  than  ferric 
benzoate ; a white  precipitate  with  acetate  of  lead,  soluble 
in  excess  of  either  reagent ; with  nitrate  of  silver  a white 
precipitate  after  a time  ; with  chloride  of  barium  no  preci- 
pitate at  first,  but  a white  one  of  succinate  of  barium  on 
the  addition  of  ammonia  and  alcohol.  Succinates  are  dis- 
tinguished from  benzoates  by  the  last-named  reaction, 
and  by  not  yielding  a precipitate  on  the  addition  of  acids 
{mde  p.  300). 

SULPHOCYANIC  AciD  (HCyS)  AND  OTHER  SULPHOCYAN- 
ATES. — Boil  together  sulphur  and  solution  of  pure  cyanide 
of  potassium  ; solution  of  sulphocyanate  of  potassium 
(KCyS)  is  formed. 

Tests, — Filter,  and  to  a small  portion  of  the  solution  add 
a ferric  salt  (Fe.^Clg) ; a deep-blood-red  solution  of  ferric 
sulphocy^anate  is  formed.  To  a portion  of  the  red  liquid 
add  hydrochloric  acid  ; the  color  is  not  discharged  (meco- 
nate  of  iron,  a salt  of  similar  tint,  is  decomposed  by  hydro- 
chloric acid).  In  the  acid  liquid  place  a fragment  or  two 
of  zinc,  sulphuretted  hydrogen  is  evolved,  and  the  red  color 
disappears.  To  another  portion  of  the  ferric  sulphocyanate 
add  solution  of  corrosive  sublimate;  the  color  is  at  once 
discharged.  (Ferric  meconate  is  unaffected  by  corrosive 
sublimate.)  The  ferric  is  the  best  test  of  the  presence  of 
a sulphocyanate;  indirectly^  it  is  a good  test  of  the  pre- 
sence of  hydrocyanic  acid  or  cy^anogen. 

To  solution  of  a sulphocy’anate  add  solution  of  mercuric 
nitrate;  mercuric  sulphocy^anate  is  precipitated  as  a wdiite 
l)Owder. 

PharaolVs  Serpents. — Mercuric  sulphocyanate,  thoroughly  washed 
and  made  up  into  little  cones,  forms  the  toy  called  Pharaoh’s  ser- 
pent. It  readily  burns  when  ignited,  the  chief  product  being  a light 
solid  matter  (mellon,  C^Nj,,  and  the  melam,  which  issues 

from  the  cone  in  a snake-like  coil  of  extraordinary  length.  The  other 
products  are  mercuric  sulphide  (of  which  part  remains  in  the  snake 
and  part  is  volatilized),  nitrogen,  sulphurous,  and  carbonic  acid 
gases,  and  vapor  of  metallic  mercury.  (For  details  concerning  the 
economical  manufacture  of  sulphocyanates  see  Pharmaceutical  Jour- 
nal, second  series,  vol.  vii.  p.  ,581,  and  p.  152.) 

The  sulphocyanic  radical  (CyS)  is  often  termed  sulphocyanogcn 
(Scy),  and  its  compounds  regarded  as  sulphocyanides. 

Tannic  Acid  or  Tannin  is  a common  astrin- 


TANNIC  ACID. 


3n 

gent  constituent  of  plants,  but  is  contained  in  largest  quantity  in 
galls  (excrescences  on  the  oak  formed  by  the  puncture  and  deposited 
ova  of  an  insect).  English  galls  contain  from  14  to  28  per  cent,  of 
tannic  acid  ; Aleppo  galls  {Galla,  B.  P.  and  U.  S.  P.)  from  25  to  65 
per  cent.  [Acidum  Tannicum,  B.  P.  and  U.  S.  P.) 

Process, — Expose  powdered  galls  (about  an  ounce  is 
sufficient  for  the  purpose  of  study)  to  a damp  atmosphere 
for  two  or  three  days,  and  afterwards  add  sufficient  ether 
to  form  a soft  paste.  Let  this  stand  in  a well-closed  vessel 
for  twenty-four  hours,  then,  having  quickly  enveloped  it  in 
a linen  cloth,  submit  it  to  strong  pressure  so  as  to  separate 
the  liquid  portion,  which  contains  the  bulk  of  the  tannin  in 
solution.  Reduce  the  pressed  cake  to  powder,  mix  it  with 
sufficient  ether,  to  which  one-sixteenth  of  its  bulk  of  water 
has  been  added,  to  form  again  a soft  paste,  and  press  this 
as  before.  Mix  the  expressed  liquids,  and  expose  the  mix- 
ture to  spontaneous  evaporation  until,  by  the  aid  subse- 
quently of  a little  heat,  it  has  acquired  tlie  consistence  of 
a soft  extract ; then  place  it  on  eartlien  plates  or  dishes, 
and  dry  it  in  a hot-air  chamber  at  a temperature  not  ex- 
ceeding 212°.^^ 

The  resulting  tannic  acid  occurs  in  “ pale  yellow  vesicu- 
lar masses  or  thin  glistening  scales,  withn,  strongly  astrin- 
gent taste,  and  an  acid  reaction,  readily  soluble  in  water 
and  rectified  spirit,  very  sparingly  soluble  in  pure  ether, 
though  soluble  in  common  ether  (which  contains  alcohol) 
when  the  ether  is  saturated  with  water. 

Medicinal  Uses, — Tannic  acid  is  very  soluble  in  water,  and  in  this 
form  is  usually  administered  in  medicine.  Its  official  preparations 
are  Glyceritum  Acidi  Tannici^  Suppositoria  Acidi  Tannici,  and 
Trochisci  Acidi  Tannici. 

Tests. — To  an  aqueous  solution  of  tannic  acid  add  aque- 
ous solution  of  gelatine,  a yellowish-white  flocculent  com- 
pound of  the  two  substances  is  precipitated.  This  is  a good 
test  of  the  presence  of  tannic  acid. 

Tanning. — The  above  reaction  also  serves  to  explain  the  chemi- 
cal principle  involved  in  tanning — the  operation  of  converting  skin 
into  leather.  In  that  process  the  skin  is  soaked  in  infusion  of  oak- 
bark  [Quercus  Cortex),  the  tannic  acid  of  which  uniting  with  the 
gelatinous  tissues  of  the  skin  yields  a compound  very  well  represented 
by  the  above  precipitate.  The  outer  bark  of  the  oak  contains  little 
or  no  tannic  acid,  and  is  commonly  shaved  off  from  the  pieces  of  bark 
which  are  large  enough  to  handle ; useless  coloring  matter  is  thus 
also  rejected.  Other  infusions  and  extracts  besides  that  of  oak-bark 
(chiefly  catechu,  sumach,  and  valonia)  are  largely  used  by  tanners ; 

27^ 


318  SALTS  OF  RARER  ACIDULOUS  RADICALS. 

if  used  alone  these  act  too  quickly,  and  give  a harsh,  hard,  less 
durable  leather.  The  tannic  acid  of  these  preparations  is  probably 
slightly  different  from  that  of  oak-bark. 

To  an  aqueous  solution  of  tannic  acid  add  a neutral  solu- 
tion of  a ferric  salt ; dark  bluish-black  tannate  of  iron  is 
slowly^  precipitated.  This  is  an  excellent  test  for  the  pre- 
sence of  tannic  acid  in  vegetable  infusions.  The  precipi- 
tate is  the  basis  of  nearly  all  black  writing-ink.  Ferrous 
salts  give  at  first  only  a slight  reaction  with  tannic  acid  ; 
but  the  liquid  gradually  darkens.  Characters  written  with 
this  liquid  become  quite  black  in  a few  hours,  and  are  very 
permanent. 

To  an  aqueous  solution  of  tannic  acid  add  solution  of 
tartar-emetic;  tannate  of  antimony  is  precipitated.  This 
reaction  and  that  with  gelatine  are  useful  in  the  quantita- 
tive estimation  of  the  amount  of  tannic  acid  in  various 
substances. 

Tannic  acid  is  a glucoside;  that  is,  like  several  other  substances, 
it  yields  glucose  (grape-sugar)  when  boiled  with  dilute  sulphuric  or 
hydrochloric  acid,  the  other  product  being  gallic  acid : — 

-f  4H,0  = 0^11, ,0^  + 3H3C,H30,. 

Catechu  [Catechu,  U.  S.  P.,  Catechu  'pallidum,  B.  P.),  Gamhir, 
or  Terra  Japonica,  Kino  [Kino,  B.  P.  and  U.  S.  P.),  Elm  Bark 
[Ulmi  Cortex,  B.  P.),  and  Slippery  Elm  Bark  [Ulmus  fulva,  U. 
S.  P.),  and  some  other  vegetable  products  contain  a variety  of  tannic 
acid  [mimo-tannic  acid),  which  gives  a greenish  precipitate  with 
neutral  solutions  of  ferric  salts. 

Bael  fruit  [Belce  fr actus,  B.  P.),  from  the  jEgle  Marmelos,  is 
said  to  owe  its  astringency  to  a variety  of  tannic  acid.  In  India  a 
jelly  and  preserve  have  long  been  made  from  the  Marmelos — whence 
the  word  marmalade  for  similar  preserves.  The  astringency  of  Pome- 
granate-root Bark  [Granati  Radicis  Cortex,  B.  P.  and  U.  S.  P.) 
and  Fruit  [Granati  Fomctus  Cortex,  U.  S.  P.)  is  due  to  tannic  acid 
(its  anthelmintic  properties  probably  to  a resinoid  matter)  ; and  the 
same  may  be  said  of  logwood  [Hoematoxyli  Lignum,  B.  P.  and  U. 
S.  P.,  the  color  which  is  due  to  oxidized  hcematoxylin).  Rhatany- 
root  [Kramerice  Radix,  B.  P.  and  U.  S.  P.)  contains  about  40  per 
cent,  of  tannic  acid,  its  active  astringent  principle ; rhubarb-root 
about  9 per  cent,  ^earfterry-leaves  (.  IJvce  Ursi  Folia,  B.  P.  and  U. 
S.  P.)  owe  most  of  their  therapeutic  power  to  about  35  per  cent,  of 
tannic  acid.  (The  cause  of  their  influence  on  the  kidneys  is  not  yet 
traced.)  They  also  contain  arhutin,  a crystalline  glucoside. 

Gallic  MczcZ(H3C,n30^,U20)  {Acidum  Gallicum^  B.  P.  and 
U.  S.  P.)  occurs  in  small  quantity  in  oak-galls  and  other 
vegetable  substances,  but  is  always  prepared  from  tannic 
acid.  Powdered  galls  are  moistened  with  water  and  set 


GALLIC  ACID. 


319 


aside  in  a warm  place  for  five  or  six  weeks,  occasionally 
being  remoistened  ; fermentation  occurs,  and  impure  gallic 
acid  is  formed.  The  product  is  treated  with  about  three 
times  its  weight  of  water,  boiled  to  dissolve  the  gallic  acid, 
filtered,  the  solution  set  aside  to.  cool,  deposited  gallic  acid 
collected,  drained,  pressed  between  folds  of  paper  to  remove 
all  mother-liquor,  and,  if  necessary,  purified  by  recrystal- 
lization from  water,  or  by  solution  in  hot  water  with  animal 
charcoal,  which  absorbs  coloring  matter.  On  filtering  and 
cooling,  most  of  the  acid  separates  in  the  form  of  fawn- 
colored  slender  acicular  crystals.  Gallic  acid  is  soluble  in 
about  100  times  its  weight  of  cold  or  3 of  boiling  water, 
freely  in  spirit,  sparingly  in  ether,  also  in  glycerine  {Gly- 
ceritum  Acidi  Gallici^  U.  S.  P.). 

The  nature  of  the  action  by  which  gallic  acid  is  thus  produced  is 
probably  similar  to  that  of  the  action  of  dilute  acids  on  tannic  acid. 
During  the  process  oxygen  is  absorbed  and  carbonic  acid  gas  evolved, 
the  sugar  being  thus  broken  up  or  perhaps  prevented  from  being 
formed. 

Test. — To  an  aqueous  solution  of  gallic  acid  add  a neu- 
tral solution  of  ferric  salt;  a bluish-black  precipitate  of 
gallate  of  iron  falls,  similar  in  appearance  to  tannate  of 
iron.  Ferrous  salts  are  also  blackened  by  gallic  acid.  To 
more  of  the  solution  add  an  aqueous  solution  of  gelatine; 
no  precipitate  occurs.  By  the  latter  test  gallic  is  distin- 
guished from  tannic  acid. 

Pyrogallic  Acid  (CgH^jOg). — This  substance  sublimes  in  light 
feathery  crystals  when  gallic  acid  is  heated.  To  an  aqueous  solu- 
tion add  a neutral  solution  of  a ferric  salt,  a red  color  is  produced. 
To  another  portion  add  a ferrous  salt;  a deep-blue  color  results. 

Test  for  the  three  acids. — To  three  separate  small  quantities  of 
milk  of  lime  in  test-tubes  add,  respectively,  tannic,  gallic,  and  pyro- 
gallic acids ; the  first  slowly  turns  brown,  the  second  more  rapidly, 
while  the  pyrogallic  mixture  at  once  assumes  a beautiful  purplish- 
red  color  changing  to  brown.  These  reactions  are  highly  character- 
istic. They  are  accompanied  by  absorption  of  oxygen  from  the  air. 

Use  of  Pyrogallic  Acid  in  Gas-analysis. — A mixture  of  pyro- 
gallic acid  and  solution  of  potash  absorbs  oxygen  with  such  rapidity 
and  completeness  that  a strong  solution  of  each,  passed  up  succes- 
sively by  a pipette  into  a graduated  tube  containing  air  or  other  gas, 
forms  an  excellent  means  of  estimating  free  oxygen.  The  value  of 
this  method  may  be  roughly  proved  by  pouring  a small  quantity  of 
each  solution  into  a phial,  immediately  and  firmly  closing  its  mouth 
with  a cork,  thoroughly  shaking  the  mixture  and  then  removing  the 
cork  under  water ; the  water  rushes  in  and  occupies  about  one-fifth 
ol*  the  previous  volume  of  air,  indicating  that  the  atmosphere  con- 
tains one-fifth  of  its  bulk  of  oxygen.  The  small  amount  of  carbonic 


320  SALTS  OP  RARER  ACIDULOUS  RADICALS. 


acid  gas  present  in  the  air  is  also  absorbed  by  the  alkaline  licpird'y^ 
in  delicate  experiments  this  thould  be  removed  by  the  alkali  before 
the  addition  of  pyrogallic  acid. 


Uric  Acid  (H.^C5H.^N^03)  and  other  Urates. — Acidulate 
a few  ounces  of  human  urine  with  h3^drochloric  acid,  and 
set  aside  for  twenty-four  hours  ; a few  minute  crystals  of 
uric  acid  will  be  found  adhering  to  the  sides  and  bottom  of 
the  vessel  and  floating  on  the  surface  of  the  liquid. 

Microscopical  Test. — Remove  some  of  the  floating  parti- 
cles by  a slip  of  glass,  and  examine  by  a powerful  lens  or 
microscope  ; the  chief  portion  will  be  found  to  be  in  yel- 
lowish semitransparent  crystals,  more  or  less  square,  two 
of  the  sides  of  which  are  even,  and  two  very  jagged  ; but 
other  forms  are  common  {oide  Frontispiece). 

Chemical  Test, — Collect  more  of  the  deposit,  place  in  a 
watch-glass  or  small  white  evaporating-dish,  remove  adhe- 
rent moisture  by  a piece  of  blotting  or  filter-paper,  add  a 
drop  or  two  of  strong  nitric  acid,  and  evaporate  to  dryness ; 
the  residue  will  be  red.  When  the  dish  is  cold,  add  a drop 
of  solution  of  ammonia ; a purplish-crimson  color  results. 
The  color  is  deepened  on  the  addition  of  a drop  of  solution 
of  potash. 


Notes, — Uric  acid  (or  lithic  acid)  and  urates  (or  litliates)  of  so- 
dium, potassium,  calcium,  and  ammonium  are  common  constituents 
of  animal  excretions.  Human  urine  contains  about  one  part  of  urate 
(usually  urate  of  sodium)  in  1000.  When  more  than  this  is  present 
the  urate  is  often  deposited  as  a sediment  in  the  excreted  urine, 
either  at  once,  or  after  standing  a short  time.  Uric  acid  or  other 
urate  is  also  occasionally  deposited  before  leaving  the  bladder, 
and,  slowly  accumulating  there,  forms  a common  variety  of  urinary 

calculus. Some  urates  are  not  definitely  crystalline ; but,  when 

treated  with  dilute  nitric  acid  or  a drop  of  solution  of  potash  and 
then  a drop  or  two  of  acetic  acid,  jagged  microscopic  crystals  of  uric 
acid  are  usually  formed. — All  urates  yield  the  crimson  color  when 
treated  as  above  described. — This  color  is  due  to  a definite  substance, 
murexid  (CgHgNgOg)  (from  the  murex,  a shell-fish  of  similar  tint) ; 
and  the  test  is  known  as  the  murexid  test.  The  formation  of  mu- 
rexid is  due  to  the  action  of  ammonia  on  alloxan  (C4H.^N.^0^,4H20) 
and  other  white  crj'Stalline  products  of  the  oxidation  of  uric  acid  by 
nitric  acid.  Murexid  is  a good  dye  ; it  may  be  prepared  from  guano 
(the  excrement  of  sea-fowl),  which  contains  a large  quantity  of  urate 
of  ammonium.  The  excrement  of  the  serpent  is  almost  pure  ammo- 
nium urate. 

Uric  acid  and  the  urates  will  be  again  alluded  to  in  connection 
with  the  subject  of  morbid  urine. 


I 


Valerianic  Acid  or  Valeric  Acid  (HCJIyOg)  and 
OTHER  Valerianates. — In  a test-tube  place  a few  drops  of 


VALERIANATES. 


321 


amylic  alcohol  (fousel  oil)  with  a little  dilute  sulphuric 
acid  and  a grain  or  two  of  red  chromate  of  potassium, 
cork  the  tube,  set  aside  for  a few  hours,  and  then  heat  the 
mixture ; valerianic  acid,  of  characteristic  valerian-like 
odor,  is  evolved. 

Valerianic  acid  occurs  naturally  in  valerian-root  in  association 
with  the  essential  oil  from  which  it  is  derived  [vide  Index),  but  is 
usually  prepared  artificially,  by  the  foregoing  process,  from  amylic 
alcohol,  to  which  it  bears  the  same  relation  as  acetic  acid  does  to 
common  alcohol : — 

O.H.HO  + O2  = HC.^H302  + H.,0 
C,H,,HO  + 0,  ==  HC,H,0,  + H;0. 

Valerianate  of  Sodium  (NaC^H^O^)  (Sodas  Valerianas^ 
B.  P.)  is  prepared  from  the  valerianic  acid  and  valerianate 
of  amyl  obtained  on  distilling  the  mixture  of  amylic  alcohol 
(4  fl.  ozs.),  sulphuric  acid  (6|-  fl.  ozs.  with  10  of  water),  and 
red  chromate  of  potassium  (9  ozs.  in  10  of  water).  The 
mixture  should  stand  for  several  hours  before  heat  is  ap- 
plied. 

2(K,Cr0,,Cr03)  + 8H,SO,=  2(K,S0„Cr,3S0,+8H,0  -f  30, 

Red  chromate  of  Sulphuric  Sulphate  of  potassium  Water.  Oxygen, 

potassium.  acid.  and  chromium. 

(Chrome  alum.) 

C,H,HO  + 0,  = HC,H,0,  + H.,0 

Amylic  Oxygen.  Valerianic  Water, 

alcohol.  acid. 

2C,H„HO  + 0,  = + 2H,0 

Amylic  Oxygen.  Valerianate  Water. 

alcohol.  of  amyl. 

The  distillate  (70  or  80  ozs.)  is  saturated  with  soda,  which  not  only 
yields  valerianate  of  sodium  with  the  free  valerianic  acid,  but  de- 
composes the  valerianate  of  amyl  produced  at  the  same  time,  more 
valerianate  of  sodium  being  formed  and  some  amylic  alcohol  set  free, 
according  to  the  following  equations  : — 

HC5H9O2  4-  NallO  = NaC^H.O^  -f  H^O 

Valerianic  Soda.  Valerianate  Water, 

acid.  of  sodium. 

+ NaHO  = NaCsH.O^  + HO 

Valerianate  Soda.  Valerianate  Amylic 

of  amyl.  of  sodium.  alcohol. 

Prom  the  solution  of  valerianate  of  sodium  (which 
should  be  made  neutral  to  test-paper  by  careful  addition 
of  soda  solution)  the  solid  white  salt  is  obtained  by  evap- 
oration to  dryness  and  cautious  fusion  of  the  residue. 
The  mass  obtained  on  cooling  should  be  broken  up  and 
kept  in  a well-closed  bottle.  It  is  entirely  soluble  in  spirit. 

Other  Valerianates^  as  valerianate  of  zinc  (Zinci  Vale- 
rianus^  B.  P.  and  U.  S.  P.),  and  ferric  valerianate,  may 
be  made  by  double  decomposition  of  valerianate  of  sodium 


322  SALTS  OF  RARER  ACIDULOUS  RADICALS. 

witli  the  sulphate  or  other  salt  of  the  metal  the  valerianate 
of  which  is  desired,  the  new  valerianate  precipitating  or 
crystallizing  out.  A hot  solution  of  sulphate  of  zinc  (5| 
parts)  and  valerianate  of  sodium  (5  parts)  in  water  (40 
parts)  gives  a crop  of  crystals  of  valerianate  of  zinc  on 
cooling. 

Tests, — Heated  with  diluted  sulphuric  acid,  valerianates 
of  the  metals  give  valerianic  acid,  which  has  a highly 
characteristic  smell.  Valerianate  of  sodium  thus  treated, 
and  the  resulting  oily  acid  liquid  purified  by  agitation 
with  sulphuric  acid  and  distillation,  furnishes  the  Acidum 
Valerianicum  of  the  United  States  Pharmacopoeia.  Sp.  gr. 
933.  Dry  ammonia  gas  passed  into  valerianic  acid  gives 
white  lamellar  crystals  of  valerianate  of  ammonium 
(Ammonii  Valerianas^  U.  S.  P.). 

The  amylic  alcohol  (C5HJJHO)  from  which  valerianates  are  pre- 
pared may  contain  the  next  lower  homologue,  hutylic  alcohol 
fC^HjjHO).  This,  during  oxidation,  will  be  converted  miohutyric  acid  \ 
(HC4H7O2),  the  next  lower  homologue  of  valerianic  acid  (HCjHyOj),  | 
and  hence  the  various  valerianates  be  contaminated  by  some  buty- 
rates. These  are  detected  by  distillation  with  diluted  sulphuric  i 
acid  and  addition  of  solution  of  acetate  of  copper  to  the  distillate, 
which  at  once  becomes  turbid  if  butyric  acid  be  present.  In  this 
reaction  valerianic  and  butyric  acids  are  produced  by  double  de- 
composition of  the  valerianate  and  butyrate  by  the  sulphuric  acid, 
and  distil  over  on  the  application  of  heat.  On  the  addition  of  acetate 
of  copper  (CU2O2H3O2)  butyrate  of  copper  (Cu2C4H702,H20)  is 
formed,  and,  being  almost  insoluble  in  water,  is  at  once  precipitated, 
or  remains  suspended,  giving  a bluish-white  opalescent  liquid. 
Valerianate  of  copper  (CU2C5H9O2)  is  also  formed  after  some  time, 
but  is  far  more  soluble  than  the  butyrate,  and  only  slowly  collects 
in  the  form  of  geenish  oily  drops,  which  gradually  pass  into  green- 
ish-blue hydrous  crystalline  valerianate  of  copper  (Larocque  and 
Huralt). 


. QUESTIONS  AND  EXERCISES.  | 

619.  What  is  the  constitution  of  nitrites?  [ 

620.  Mention  a test  for  nitrites  in  potable  waters.  ! 

621.  Which  nitrite  is  official? 

622.  Give  the  names  of  some  natural  and  artificial  silicates. 

623.  What  is  “ soluble  glass  ?”  ' 

624.  Distinguish  between  silica  and  silicic  acid.  ' 

625.  How  are  silicates  detected  ? 

626.  What  is  the  quantivalence  of  silicon  ? 

627.  Mention  the  sources,  formulae,  and  analytical  reactions  of  i 
succinates. 

628.  State  the  mode  of  manufacture  and  tests  of  sulphocyanates. 

629.  What  proportion  of  tannic  acid  is  contained  in  galls  ? 


DETECTION  OF  ACIDULOUS  RADICALS.  323 


630.  Describe  the  official  process  for  the  preparation  of  Tannic 
Acid. 

631.  Explain  the  chemistry  of  ‘‘  tanning.” 

632.  Enumerate  the  tests  for  tannic  acid  ? 

633.  What  is  the  assumed  constitution  of  tannic  acid  ? 

634.  Mention  other  official  substances  whose  astringency  is  due  to 
tannic  acid. 

635.  How  is  gallic  acid  prepared  ? 

636.  By  what  reaction  is  gallic  distinguished  from  tannic  acid  ? 

637.  Mention  the  characteristic  properties  of  pyrogallic  acid. 

638.  Explain  the  murexid  test  for  uric  acid. 

639.  Describe  the  artificial  preparation  of  valerianic  acid  and 
other  valerianates,  giving  diagrams  or  equations. 

640.  What  is  the  formula  of  valerianic  acid  ? 

641.  How  are  butyrates  detected  in  presence  of  valerianates  ? 


DETECTION  OF  THE  ACIDULOUS  RADICALS  OF 
SALTS  SOLUBLE  IN  WATER. 

Analytical  operations  may  now  be  resumed,  the  detection  of  acid- 
ulous radicals  being  practised  for  two  or  three  days,  and  then  full 
analyses  made,  both  for  basylous  and  acidulous  radicals.  To  this 
end  a few  compounds  of  stated  metals  (potassium,  sodium,  or  ammo- 
nium) should  be  placed  in  the  hands  of  the  practical  student  for 
examination  according  to  the  following  paragraphs  and  Tables. 
Mixtures  in  which  both  basylous  and  acidulous  radicals  may  be 
sought  should  then  be  analyzed. 

In  examining  salts  soluble  in  water,  and  concerning  which  no  gene- 
ral information  is  obtainable,  search  must  first  be  made  for  any  basy- 
lous radicals  by  the  appropriate  methods  [vide  pages  196  or  229). 
Certain  metals  having  been  thus  detected,  a little  reflection  on  the 
character  of  their  salts  will  at  once  indicate  what  acidulous  radicals 
may  be,  and  what  cannot  be,  present.  Thus,  for  instance,  if  the  sub- 
stance under  examination  is  freely  soluble  in  water,  and  lead  is  found, 
only  the  nitric  and  acetic  radicals  need  be  sought,  none  other  of  the 
lead  salts  than  nitrate  or  acetate  being  freely  soluble  in  water. 
Moreover,  the  salt  is  more  likely  to  be  acetate  than  nitrate  of  lead, 
for  two  reasons  : the  former  is  more  soluble  than  the  latter,  and  is  by 
far  the  commoner  salt  of  the  two.  Medical  and  pharmaceutical 
students  have  probably,  in  dispensing,  already  learned  much  concern- 
ing the  solubility  of  salts,  and  whether  a salt  is  rarely  employed  or 
in  common  use.  And  although  but  little  dependence  can  be  placed 
on  the  chances  of  a salt  being  present  or  absent  according  to  its 
rarity,  still  the  point  may  have  its  proper  weight.  If,  in  a mixture 
of  salts,  ammonium,  potassium,  and  magnesium  have  been  found 
associated  with  the  sulphuric,  nitric,  and  hydrochloric  radicals,  and 
we  are  asked  how  we  suppose  these  bodies  may  exist  in  the  mixture, 
it  is  far  more  in  accordance  with  common  sense  to  suggest  that  sal- 
ammoniac,  nitre,  and  Epsom  salt  were  originally  mixed  together  than 
to  suppose  any  other  possible  combination.  Such  appeals  to  expe- 
rience regarding  the  solubility  or  rarity  of  salts  cannot  be  made  by 


324  DETECTION  OP  ACIDULOUS  RADICALS. 

any  one  not  previously  acquainted,  or  insufficiently  acquainted,  with 
the  characters  of  salts  ; in  such  , cases  the  relation  of  a salt  to  water 
and  acids  can  be  ascertained  by  referring  to  the  following  Table 
(p.  325)  of  the  solubility  or  insolubility  of  about  five  hundred  of  the 
common  or  rarer  salts  met  with  in  chemical  operations. 

The  opposite  course  to  the  above  (namely,  to  acertain  what  acidu- 
lous radicals  are  present  in  a mixture,  and  then  to  appeal  to  expe- 
rience to  tell  what  basylous  radicals  n^y  be  and  what  cannot  be 
present)  is  impracticable  ; for  acidulous  radicals  cannot  be  separated 
out,  one  after  the  other,  from  one  and  the  same  quantity  of  substance 
by  a similar  treatment  to  that  already  given  for  basylous  radicals. 
Indeed  such  a sifting  of  acidulous  radicals  could  scarcely  be  accom- 
plished at  all,  or  only  by  a vast  deal  of  labor.  The  basylous  radicals 
must,  therefore,  be  first  detected. 

Even  when  the  basylous  radicals  have  been  found,  the  acidulous 
radicals  which  may  be  present  must  be  sought  for  singly,  the  only 
additional  aid  which  can  be  brought  in  being  the  action  of  sulphuric 
acid,  a barium  salt,  a calcium  salt,  nitrate  of  silver,  and  ferric  chlo- 
ride on  separate  small  portions  of  the  solution  under  examination, 
as  detailed  in  the  second  of  the  following  Tables. 

Commence  the  analysis  of  an  aqueous  solution  of  a salt 
or  salts,  the  bas3Tous  radicals  in  which  are  known,  by 
writing  out  a list  of  the  acidulous  radicals  which  may  be,  i 
or,  if  more  convenient,  of  those  which  cannot  be  present. 
To  this  end  consult  the  following  Table  (p.  325)  of  the 
solubility  of  salts  in  water.  Look  for  the  name  of  the 
metal  of  the  salt  in  the  vertical  column;  the  letters  S and 
I indicate  which  salts  are  soluble  and  which  insoluble  in 
water,  an  asterisk  attached  to  the  S meaning  that  the  salt 
is  slightly  soluble.  The  acidulous  part  of  the  name  is 
given  in  the  top  line  of  the  Table.  All  the  names  are  in 
alphabetical  order,  for  facility  of  reference. 

Some  of  the  salts  marked  as  insoluble  in  Tvater  are  soluble  in 
aqueous  solutions  of  soluble  salts,  a few  forming  soluble  double  salts. 
To  characterize  salts  as  soluble,  slightly  soluble,  or  insoluble,  only 
roughly  indicates  their  relation  to  water : on  the  one  hand,  very  few 
salts  are  absolutely  insoluble  in  water ; on  the  other,  there  is  a limit 
to  the  solubility  of  every  salt.  I 

If  only  one^  two^  or  perhaps  three  given  acidulous  radi-'\ 
cals  can  be  in  the  liquid^  test  directly  for  it  or  them  accord-  j 
ing  to  the  reactions  gicen  in  the  previous  pages.  If  seceral  \ 
may  he  present,^  pour  small  portions  of  the  solutions^  ren-  \ 
dered  neutral  if  necessary  by  ammonia^  into  five  test-tubes  A 
and  add  respectively  sulphui'ic  acid^  nitrate  or  chloride  of  .\ 
barium,^  chloride  of  calcium,,  nitrate  of  silver,,  and  ferric\ 
chloride;  then  consult  the  Table  on  page  326,  in  order  to: 
correctly  interpret  the  effects  these  reagents  may  have  pro- 
duced. 


DETECTION  OF  ACIDULOUS  RADICALS.  325 


•ejp.na'ex 

MkhXo-. 

•8?tqclitis 

<e-.  &o>-.  ^-xC/^&e-.  <>-.  S^iXlCCh-iCQe-.  1— i»-hM 

•epiqding 

•ej'Bqdxng 

mm  maim 

•9}^qdsoqti 

•0pTXO 

I-hCQi-H*— lCC»-HI— *CQhHH-(C/2hH 

t— iC/JOJhhi— tt— 11— HHHHI— CCt-HCCCQ|-HHH»-l 

maics-mmmmmmmmmc^.mmaimmmmmmmmmmm 

•0pTpOI 

o^.  m ^ m ^ m m m ai  >~A  m m >--i%i  m m ^ mmm  m ai  m m m 

•0]^.ipiCH 

|l--<l--(l--(S2l-HI-HhH<>..  HHI-hCCo-.  CQi-Hi-hCQcw. 

'OpUCBiCQ 

e>-.  ai  0-.  m o—  o-  ai  hh  i— i hh  i-h  »-•  t-H  m o—  h-i  o-.  ai  i— i ai  «>—  »-.  ai  >— i 

*0)^uio.iii3 

^ m h-^  m ^ e^.  m m <>..  0-.  i->  m mm  ^ ^ e^.  m ^ m ^ ^ ^ m 

•0;'bj;tO 

"m  m o^.mmmm  ai  m m m m a^.m  m ^ ^ m »..  m ^ m <>..  o^.  ^m 

•0pi.ioiqo 

'0}'Baoq.ii?3 

I— iCOtV.  t— !►— (t— 1(— ll-Ht— II— •©-.  HHO-I— (HHI— II— IK-IHHe-.  CQl— (CCo-.  0-.  t-HI— I 

*0)iu0Sjy 

•— 'CZ2l— II— («>-.  Ow.  HHO-h- <1— IH- I-HI— («V.  1— II— II— IO-.  CCl— iCChHI— II— (0-. 

•aj'Bta0sJv 

•0i‘B}0Dy 

ai  m m m m m m m m m m m o^.  m m m mm  m mm  m m m m m 

28 


326  DETECTION  OF  ACIDULOUS  RADICALS. 


REMARKS  ON  THE  PRECEDING  TABLE. 

The  first  point  of  value  to  be  noticed  in  connection  with  this  Table 
is  one  of  a negative  character;  namely,  if  either  of  the  reagents 
gives  no  reaction  it  is  self-evident  that  the  salts  which  it  decomposes 
with  production  of  a precipitate  must  be  absent.  Then,  again,  if 
the  action  of  one  of  the  reagents  indicates  the  absence  of  certain 
acidulous  radicals,  those  radicals  cannot  be  precipitated  by  the  other 
reagents ; thus,  if  the  action  of  sulphuric  acid  points  to  the  absence 
of  sulphides,  sulphites,  carbonates,,  cyanides,  and  acetates,  these  salts 
may  be  struck  out  of  the  other  lists,  and  the  examination  of  subse- 
quent precipitates  be  so  far  simplified.  Or,  if  the  barium  precipitate 
is  soluble  in  hydrochloric  acid  and  the  calcium  precipitate  in  acetic 
acid,  neither  sulphates  nor  oxalates  can  be  present.  Observing 
these  and  other  points  of  difference,  which  will  be  seen  on  careful 
and  thoughtful  reflection,  and  remembering  the  facts  suggested  by  a 
knowledge  of  what  basylous  radicals  are  present,  one  acidulous  radi- 
cal after  the  other  may  be  struck  off  as  absent  or  present,  leaving 
only  one  or  two  as  the  objects  of  special  experiment.  Among  the 
chief  difficulties  to  be  encountered  will  be  the  separation  from  each 
other  of  chlorides,  bromides,  iodides,  and  cyanides,  or  of  tartrates 
from  citrates,  and  confirmatory  tests  of  the  presence  of  certain  com- 
pounds. These  may  all  be  surmounted  on  referring  back  to  the 
reactions  of  the  various  radicals,  as  described  under  their  hydrogen 
salts,  the  acids. 

The  rarer  acidulous  radicals  will  very  seldom  be  met  with.  Ben- 
zoates, hippurates  (which  give  benzoic  acid),  hypochlorites,  hyposul- 
phites, nitrites,  and  valerianates  show  themselves  under  the  sulphuric 
treatment.  Ferrocyanides,  ferridcyanides,  meconates,  succinates, 
sulphocyanates,  t annates,  and  gallates  appear  among  the  salts  whose 
presence  is  indicated  by  ferric  chloride  ; formiates,  hypophosphites, 
malates,  and  others  by  nitrate  of  silver.  Urates  char  when  heated, 
giving  an  odor  resembling  that  of  burnt  feathers. 

In  actual  practice  the  analyst  nearly  always  has  some  clue  to  the 
nature  of  rarer  substances  placed  in  his  hands. 

If  chromium  and  arsenicum  have  been  detected  among  the  basy- 
lous radicals,  those  elements  may  be  present  in  the  form  of  chromates, 
arseniates,  and  arsenites,  yielding  with  chloride  of  barium  yellow 
chromate  of  barium  and  white  arseniate  and  arsenite  of  barium,  and 
with  nitrate  of  silver  red  chromate,  brown  arseniate,  and  yellow 
arsenite  of  silver. 


QUESTIONS  AND  EXERCISES. 

642.  In  analyzing  an  aqueous  solution  of  salts,  for  which  radicals 
would  you  first  search,  the  basylous  or  the  acidulous  ? and  why  ? 

643.  In  an  aqueous  solution  there  have  been  found  magnesium 
(Mg)  and  potassium  (K),  with  the  sulphuric  radical  (SO4),  and 
iodine  (I) ; state  the  nature  of  the  salts  which  were  originally  dis- 


328 


GENERAL  QUALITATIVE  ANALYSIS. 


solved  in  the  water,  and  mention  the  principles  which  guide  you  in 
the  conclusions. 

644.  Give  a sketch  of  the  method  by  which  to  analyze  a neutral  ■ 
or  only  faintly  acid  aqueous  liquid  for  the  acidulous  radical  of  salts. 

In  what  stage  of  the  process  would  the  following  sstlts  be  detected  ? 

a.  Carbonates  and  Sulphates. 

h.  Oxalates. 

c.  Tartrates  and  Nitrates. 

d.  Acetates  and  Sulphites. 

e.  Bromides  and  Cyanides. 

/.  Borates. 

g.  Iodides  and  Phosphates. 

li.  Chlorates,  Oxalates,  and  Acetates. 

i.  Chlorides  and  Iodides. 

j.  Sulphites.  i 

k.  Sulphides,  Carbonates,  and  Nitrates.  | 

l.  Citrates  and  Sulphates.  ' 

645.  Nitrate  of  silver  gives  no  precipitate  in  an  aqueous  solution  ; | 

what  salts  may  be  present  ? | 

646.  Chloride  of  barium  gives  no  precipitates  in  a neutral  solu-  i 

tion,  but  nitrate  of  silver  a white  ; what  acidulous  radicals  are  indi-  [ 
cated  ? j 

647.  Ferric  chloride  produces  a deep  red  color  in  a solution,  chlo-  i 

ride  of  calcium  yielding  no  precipitate ; what  salts  may  be  present,  ; 
and  how  might  they  be  distinguished  from  each  other  ? ] 

648.  Ferric  chloride  gives  a black  precipitate  in  a solution  in  i 
which  sulphuric  acid  develops  no  odor ; to  what  is  the  effect  due  ? 


AI^ALYSIS  OF  SALTS, 

SINGLE  OR  MIXED,  SOLUBLE  OR  INSOLUBLE.  I 

Thus  far  all  material ’^substances,  especially  those  of  pharmaceu-  | 
tical  interest,  have  been  regarded  as  being  definite  compounds,  and  j 
as  having  certain  well-defined  parts,  termed,  for  convenience,  basy- 
lous  and  acidulous  respectively : moreover  attention  has  been  de-  : 
signedly  restricted  to  those  definite  compounds  which  are  soluble  in 
water.  ^^But  there  are  many  substances  having  no  definite  or  known 
composition  ; and  of  those  having  definite  composition  there  are 
many  having  no  definite  or  ascertained  parts.  Again,  of  those 
having  definite  composition,  and  whose  constitution  admits  of  the  ^ 
entertainment  of  theory,  there  are  many  insoluble  in  water. 

Chemical  substances  of  whose  composition  or  constitution  little  or  f 
nothing  is  at  present  known,  are  chiefly  of  animal  and  vegetable 
origin,  and  figure  in  tables  of  analysis  under  the  convenient  collec- 
tive title  of  “ extractive  matter;”  they  are  not  of  immediate  impor- 
tance, and  may  be  omitted. 


PRELIMINARY  EXAMINATIONS. 


329 


Of  substances  which  are  definite  in  composition,  but  whose  parts 
or  radicals,  if  they  have  any,  are  unknown  or  imperfectly  known, 
there  are  only  a few  (such  as  the  alkaloids,  amylaceous  and  saccha- 
rine matters,  the  glucosides,  alcoholic  bodies,  albuminoid,  fatty, 
resinoid,  and  colorific  substances)  which  have  any  considerable  amount 
of  pharmaceutical  interest ; these  will  be  noticed  subsequently. 

Definite  compounds  most  frequently  present  themselves ; and  of 
these  by  far  the  larger  proportion  (namely,  the  salts  soluble  in  water) 
have  already  been  fully  studied.  There  remain,  however,  many  salts 
which  are  insoluble  in  water,  but  which  must  be  brought  into  a state 
of  solution  before  they  can  be  effectively  studied  from  an  analytical, 
pharmaceutical,  or  a physiological  point  of  view.  The  next  subject 
of  laboratory  work  is  therefore  the  analysis  of  substances  which  may 
or  may  not  be  soluble  in  water.  This  will  involve  no  other  analyti- 
cal schemes  than  those  which  have  been  given,  will  in  only  one  or 
two  cases  increase  the  difficulty  of  the  analysis  of  the  precipitate  pro- 
duced by  a group-reagent,  but  will  give  roundness,  completeness,  and^ 
a practical  bearing  to  the  reader’s  analytical  knowledge.  Such  a 
procedure  will  at  the  same  time  bring  into  notice  the  methods  by 
which  substances  insoluble  in  water  are  manipulated  for  pharmaceu- 
tical purposes,  or  made  available  for  use  as  food  by  plants,  or  as  food 
and  medicine  by  man  and  animals  generally. 

Preliminary  Examination  of  Solid  [chiefly  mineral)  Salts. 

Before  attempting  to  dissolve  a salt  for  analysis,  its  appearance 
and  other  physical  properties  should  be  noted,  and  the  influence  of 
heat  and  strong  sulphuric  acid  be  ascertained.  If  the  operator  knows 
how  to  interpret  what  is  thus  observed,  and  to  what  extent  to  place 
confidence  in  the  observations,  he  may  more  certainly  obtain  a high 
degree  of  precision  in  analysis,  and  will  always  gain  some  valuable 
negative  information.  But  if  he  has  only  slight  experience  of  the 
appearance  and  general  properties  of  bodies,  or  has  the  habit  of  turn- 
ing what  should  be  inferences  from  tentative  processes  into  foregone 
conclusions,  he  should  omit  the  preliminary  examination  altogether, 
or  only  follow  it  out  under  the  guidance  of  a judicious  tutor  ; for  it 
is  impracticable  here  to  do  more  than  hint  at  the  results  which  may 
be  obtained  by  such  an  examination,  or  to  so  adapt  description  as 
to  prevent  a student  from  allowing  unnecessary  weight  to  precon- 
ceived ideas. 

Whatever  be  the  course  pursued,  short  memoranda  describing  re- 
sults should  invariably  be  entered  in  the  note  book. 

1.  Examine  thephy^sical  characters  of  the  salt  in  various 
ways,  but  never,  or  only  rarely,  by  the  palate,  on  account 
of  the  clanger  to  be  apprehended. 

If  the  salt  is  white,  colored  substances  cannot  be  present ; if  co- 
lored, the  tint  may  indicate  the  nature  of  the  substance  or  of  one  of 
its  constituents,  supposing  that  the  learner  is  already  acquainted 
with  the  colors  of  salts.  Closer  observation,  aided  perhaps  by  a 
lens,  may  reveal  the  occurrence,  in  a pulverulent  mixture,  of  small 

28* 


330 


GENERAL  QUALITATIVE  ANALYSIS. 


crystals  or  pieces  of  a single  substance  ; these  should  be  picked  out 
by  a needle  and  examined  separately.  In  a powder  or  roughly  di- 
vided mixture  of  substances,  the  process  of  sifting  (through  such 
sieves  as  muslin  of  different  degrees  of  fineness)  often  mechanically 
separates  substances,  and  thus  greatly  facilitates  analysis.  The 
body  may  present  an  undoubted  metallic  appearance,  in  which  case 
only  the  metals  existing  under  ordinary  atmospheric  conditions  need 
be  sought.  Peculiarity  in  smell  reveals  the  presence  of  ammonia, 
hydrocyanic  acid,  hydrosulphuric  acid,  etc.  Between  the  fingers  a 
substance  is,  perhaps,  hard,  soft,  or  gritty  ; consequent  inferences 
follow.  Or  the  matter  may  be  heavy,  like  the  salts  of  barium  or 
lead ; or  light,  like  the  carbonates  and  hydrates  of  magnesium. 

2.  Place  a grain  or  two  of  the  salt  in  a small  dry  test- 
tube  or  in  a piece  of  ordinary  tubing,  closed  at  one  end, 
and  heat  it,  at  first  gently,  then  more  strongly,  and  finally, 
if  necessary,  by  the  blowpipe. 

Gases  or  vapors  of  characteristic  appearance  or  odor  may  be 
evolved ; such  as  iodine,  nitrous  fumes,  sulphurous,  hydrocyanic,  or 
ammoniacal  gases.  Much  steam  given  by  a dry  substance  indicates 
either  hydrates  or  salts  containing  w^ater  of  crystallization.  (A 
small  quantity  of  interstitial  moisture  often  causes  heated  crystalline 
substance  to  decrepitate — from  decrepo,  to  crackle — that  is,  break 
up  with  slight  explosive  violence,  owing  to  the  expansive  force  of 
the  steam  suddenly  generated.)  A sublimate  may  be  obtained,  due 
to  salts  of  mercury  or  arsenicum,  to  oxalic  or  benzoic  acid,  or  to  sul- 
phur free  or  as  a sulphide — a salt  wholly  volatile  containing  such 
substances  only.  The  compound  may  blacken,  pointing  to  the  pre- 
sence of  organic  matter-^which,  in  common  definite  salts,  wdll  pro- 
bably be  in  the  form  of  acetates,  tartrates,  and  citrates,  or  as  common 
salts  of  the  alkaloids  morphia,  quinia,  strychnia,  or  as  starch,  sugar, 
salicin,  or  in  other  definite  or  indefinite  forms  common  in  pharmacy 
and  for  which  tests  wull  be  given  in  subsequent  pages.  If  no  char- 
ring occurs,  the  important  fact  that  no  organic  matter  is  present  is 
established.  The  residue  may  change  color  from  presence  or  devel- 
opment of  oxide  of  zinc,  oxide  of  iron,  etc.,  or  melt  from  the  presence 
of  a fusible  salt  and  absence  of  any  large  proportion  of  infusible  salt, 
or  be  unaltered,  showing  the  absence  of  any  large  amount  of  such 
substances. 

3.  Place  a grain  or  two  of  the  salt  in  a test-tube,  add  a 
drop  or  two  of  strong  sulphuric  acid,  cautiously  smelling 
any  gas  that  may  be  evolved  ; afterward  slowly  heat  the 
mixture,  noticing  the  effect,  and  stopping  the  experiment 
when  any  sulphuric  fumes  begin  to  escape. 

Iodine,  bromine,  and  nitrous  or  chlorinoid  fumes  will  reveal  them- 
selves by  their  color,  indicating  the  presence  of  iodides,  bromides, 
iodates,  bromates,  nitrates,  and  chlorates.  The  evolution  of  a color- 
le.ss  gas  fuming  on  coming  into  contact  with  air,  and  liaving  an  irri- 
tating odor,  points  to  chlorides,  fluorides,  or  nitrates.  Gaseous 


METHODS  OF  EFFECTING  SOLUTION.  331 


products  having  a greenish  color  and  odor  of  chlorine  indicate  chlo- 
rates, hypochlorites,  or  chlorides  mixed  with  other  substances. 
Slight  sharp  explosions  betoken  chlorates.  Evolution  of  colorless 
gas  may  proceed  from  cyanides,  acetates,  sulphides,  sulphites,  carbo- 
nates, or  oxalates.  Charring  will  be  due  to  citrates,  tartrates,  or 
other  organic  matter.  If  none  of  these  effects  are  produced,  most  of 
the  bodies  are  absent  or  only  present  in  minute  quantity.  The  sub- 
stances apparently  unaffected  by  the  treatment  are  metallic  oxides, 
borates,  sulphates,  and  phosphates. 

4.  Exposure  of  the  substance  to  the  blowpipe-flarae,  on 
platinum  vrire  with  or  without  a bead  of  borax  or  of  micro- 
cosmic  salt  (phosphate  of  sodium,  ammonium,  and  hydro- 
gen, NaAinHPOJ — on  platinum  foil,  in  a porcelain  crucible, 
or  on  a crucible  lid  with  or  without  carbonate  of  sodium — 
on  charcoal,  alone  or  in  conjunction  with  carbonate  of 
sodium,  cyanide  of  potassium,  or  nitrate  of  cobalt,  will 
sometimes  yield  important  information,  especially  to  one 
who  has  devoted  much  attention  to  reactions  producible  by 
the  blowpipe-flame.  The  interior  portions  of  the  flame  con- 
sist of  hydrocarbon  gases  heated  to  a temperature  at  which 
they  combine  with  oxygen  with  great  avidity,  abstracting 
that  element  from  metallic  oxides  or  other  oxidized  sub- 
stance which  maybe  brought  within  their  influence;  the 
exterior  portions,  on  the  other  hand,  contain'  excess  of 
heated  oxygen ; the  former  is  the  reducing^  the  latter  the 
oxidizing  part  of  the  flame.  The  medical  or  pharmaceutical 
student,  however,  will  seldom  have  time  to  work  out  this 
subject  to  an  extent  sufficient  to  make  it  a trustworthy 
guide  in  analysis.  (See  Plattner  and  Muspratt  On  the 
Use  of  the  Blowq^ipe,’^  and  a chapter  in  Galloway’s  ‘‘Manual 
of  Qualitative  Analysis.”) 

Methods  of  dissolving  and  analyzing  single  or  mixed  solid 
substances. 

Having  submitted  the  substance  to  'preliminary  examination, 
proceed  to  dissolve  and  analyze  by  the  following  methods.  These 
operations  consist  in  treating  a substance  well  powdered,  consecu- 
tively with  cold  or  hot  water,  hydrochloric  acid,  nitric  acid,  nitro- 
hydrochloric  acid,  or  fusion  with  alkaline  carbonates  and  solu- 
tion of  the  product  in  water  and  acid.  Resulting  liquids  are 
analyzed  in  the  manner  already  described,  or  by  slightly  modified 
processes  as  detailed  in  the  following  paragraphs. 

Solution  in  Water. — Boil  about  a grain  of  the  salt  pre- 
sented for  analysis  in  about  a third  of  a test-tubeful  of 
w ater.  If  it  dissolves  prepare  a solution  of  about  20  or  30 


332  GENERAL  QUALITATIVE  ANALYSIS. 


grains  in  half  an  ounce  or  more  of  water,  and  proceed  with 
the  analysis  in  the  usual  way^  testing  first  for  the  basy- 
lous  radical  or  radicals  by  the  proper  group  reagents 
(HCl,  H^S,  AmllS,  Ani.^CO,,  Am.^HPOJ,  pp.  199  or  230, 
and  then  for  the  acidulous  radical  or  radicals,  directly  or 
by  aid  of  the  prescribed  reagents  (H^SO^,  BaCl^,  CaCl^, 
AgNO.„  Fe,Cl„),  p.  326. 

If  the  salt  is  not  wholly  dissolved  by  the  water,  ascer- 
tain whether  or  not  any  has  entered  into  solution,  by 
filtering,  if  necessary,  and  evaporating  a drop  or  two  of 
the  clear  liquid  to  dryness  on  platinum  foil ; the  presence 
or  absence  of  a residue  gives  the  information  sought.  If 
anything  is  dissolved,  prepare  a sufficient  quantity  of  solu- 
tion for  analysis  ancl  proceed  as  usual,  reserving  the  in- 
soluble portion  of  the  mixture,  after  thoroughly  exhausting 
with  water  for  subsequent  treatment  by  acids. 

Solution  in  Hydrochloric  Acid. — If  the  salt  is  insoluble 
in  water,  digest  about  a grain  of  it  (or  of  the  insoluble 
portion  of  a mixed  salt)  in  a few  drops  of  hydrochloric 
acid,  adding  water,  and  boiling  if  necessary.  If  the  salt 
w'holly  dissolves,  prepare  a sufficient  quantity  of  the  liquid, 
noticing  whether  or  not  any  effervescence  (due  to  the 
presence  of  sulphides,  sulphites,  carbonates,  or  cyanides) 
occurs,  and  proceed  with  the  analysis  as  before,  except 
that  the  first  step,  the  addition  of  hydrochloric  acid,  may 
be  omitted. 

llie  analysis  of  this  solution  will  in  most  repects  he  simpler  than 
that  of  an  aqueous  solution,  inasmuch  as  the  majority  of  salts  (all 
those  soluble  in  water)  will  be  absent.  This  acid  solution  will,  in  short, 
only  contain  : chlorides  produced  by  the  action  of  the  hydrochloric 
acid  on  sulphides,  sulphites,  carbonates,  cyanides,  oxides,  and  hy- 
drates ; and  certain  borates,  oxalates,  phosphates,  tartrates,  and 
citrates  (possibly  silicates  and  fluorides)  which  are  insoluble  in 
water  but  soluble  in  acids  without  apparent  decomposition.  The 
first  four — sulphides,  sulphites,  carbonates,  and  cyanides — will  have 
revealed  themselves  by  the  occurrence  of  effervescence  during  solu- 
tion ; and  the  presence  of  oxides  and  hydrates  may  often  be  inferred 
by  the  absence  of  compatible  acidulous  radicals.  The  borates,  oxa- 
lates, phosphates,  tartrates,  and  citrates  alluded  to  will  be  reprecipi- 
tated in  the  general  analj^sis  as  soon  as  the  acid  of  the  solution  is 
neutralized ; that  is,  will  come  down  in  their  original  state  when 
ammonia  and  sulphydrate  of  ammonium  are  added  in  the  usual 
course.  Of  these  precipitates,  only  the  oxalate  of  calcium  and  the 
phosphates  of  calcium  and  magnesium  need  occupy  attention  now ; 
for  oxalate  and  phosphate  of  barium  seldom  or  never  occur,  and  the 
borates,  tartrates,  and  citrates  met  with  in  medicine  or  in  general 
analysis  are  all  soluble  in  water.  These  phosphates  and  oxalates, 


METHODS  OF  EFFECTING  SOLUTION. 


333 


then,  will  be  precipitated  in  the  course  of  analysis  along  with  iron, 
their  presence  not  interfering  with  the  detection  of  any  other  metal. 
If,  from  the  unusual  light  color  of  the  ferric  precipitate,  phosphates 
and  oxalates  are  suspected,  the  precipitate  is  treated  according  to 
the  following  Table  (reference  to  which  should  be  inserted  in  the 
Table  for  metals,  under  Fe,  pp.  199  and  230). 

PRECIPITATE  OP  PHOSPHATES,  OXALATES,  AND  FERRIC 
HYDRATE. 


Dissolve  in  HCl,  add  citric  acid,  then  NH^HO,  and  filter. 


Filtrate 

Fe 

Add  HCl  and 
K,Pcy 

Precipitate. 

Ca32PO„  CaC,04,  Mg,2PO,. 

Boil  in  acetic  acid  and  filter. 

Blue  ppt. 

Insoluble 

Filtrate 

CaCA- 

Ca32P04, 

Mg32P04. 

White. 

Add  Am2C204,  stir,  filter. 

Precipitate 
white,  indicating 
Ca32PO,. 

Filtrate, 

Add  AmHO. 
White  ppt. 
MgNH.PO,. 

In  analyzing  phosphates  and  oxalates  advantage  is  also  frequently 
taken  of  the  facts  that  the  phosphoric  radical  is  wholly  removed 
from  solution  of  phosphates  in  acid  by  the  addition  of  an  alkaline 
acetate,  ferric  chloride,  and  subsequent  ebullition,  as  described  under 
“ Phosphoric  Acid”  (p.  293),  and  that  dry  oxalates  are  converted 
into  carbonates  by  heat,  as  mentioned  under  “ Oxalic  Acid”  (p.  282). 

Certain  arseniates  and  arsenites,  insoluble  in  water  but  soluble  in 
hydrochloric  acid,  may  accompany  the  above  phosphates  and  oxalates 
if  from-any  cause  hydrosulphuric  acid  gas  has  not  been  previously 
passed  through  the  solution,  or  passed  for  an  insufficient  length  of 
time. 

If  the  substance  insoluble  in  water  does  not  wholly  dis- 
solve in  hydrochloric  acid,  ascertain  if  any  has  entered  into 
solution,  by"  filtering,  if  necessary,  and  evaporating  a drop 
of  the  clear  liquid  to  dryness  on  platinum  foil ; the  pre- 
sence or  absence  of  a residue  gives  the  information  sought. 
If  anything  is  dissolved,  prepare  a sufficient  quantity  of 
solution  for  analysis,  and  proceed  as  usual,  reserving  the 
insoluble  portion  of  the  mixture,  after  thoroughly  exhaust- 
ing with  hydrochloric  acid  and  well  washing  with  water, 
for  the  following  treatment  by  nitric  acid. 


334  GENERAL  QUALITATIVE  ANALYSIS. 


Solution  in  Nitric  Acid. — If  the  salt  is  insoluble  in 
M^ater  and  hydrochloric  acid,  boil  it  (or  that  part  of  it 
which  is  insoluble  in  those  menstrua)  in  a few  drops  of 
nitric  acid.  If  it  wholly  dissolves,  remove  excess  of  acid 
by  evaporation,  dilute  with  water,  and  proceed  with  the 
analysis. 

This  nitric  solution  can  contain  only  very  few  substances ; for  nearly 
all  salts  soluble  in  nitric  acid  are  also  soluble  in  hydrochloric  acid, 
and  therefore  will  have  been  previously  removed.  Some  of  the  metals, 
however  (Ag,  Cu,  Hg,  Pb,  Bi),  as  well  as  amalgams  and  alloys,  un- 
affected or  scarcely  affected  by  hydrochloric  acid,  are  readily  attacked 
and  dissolved  by  nitric  acid.  Many  of  the  sulphides,  also  insoluble 
in  hydrochloric  acid,  are  dissolved  by  nitric  acid,  usually  with  sepa- 
ration of  sulphur.  Calomel  is  converted,  by  long  boiling  with  nitric 
acid,  into  mercuric  chloride  and  nitrate.  The  nitrates  here  produced 
are  soluble  in  water. 

'Jliis  nitric  solution,  as  well  as  the  hydrochloric  and  aqueous  solu- 
tions, should  be  examined  separately.  Apparently  time  would  be 
saved  by  mixing  the  three  solutions  together  and  making  one  analysis. 
But  the  object  of  the  analyst  is  to  separate  every  radical  from  every 
other ; and  when  this  has  been  partially  accomplished  by  solvents,  it 
would  be  unwise  to  again  mix  and  separate  a second  time.  More- 
over, solvents  often  do  what  the  chemical  reagents  cannot — namely, 
separate  salts  from  each  other.  This  is  important,  inasmuch  as  the 
end  to  be  obtained  in  analysis  is  not  only  an  enumeration  of  the 
radicals  present,  but  a statement  of  the  actual  condition  in  which 
they  are  present ; the  analyst  must,  if  possible,  state  of  what  salts  a 
given  mixture  was  originally  formed — how  the  basylous  and  acidulous 
radicals  were  originally  distributed.  In  attempting  this,  much  must 
be  left  to  theoretical  considerations  ; but  a process  by  which  the  salts 
themselves  are  separated  is  of  trustworthy  practical  assistance ; 
hence  the  chief  advantage  of  analyzing  separately  the  solutions  re- 
sulting from  the  action  of  water  and  acids  on  a solid  substance. 

Solution  in  Nitro- Hydrochloric  Acid. — If  the  salt  or  any 
part  of  a mixture  of  salts  is  insoluble  in  water,  hydro- 
chloric acid,  and  nitric  acid,  digest  it  in  nitro-hydrochloric 
acid,  boiling,  if  necessary ; evaporate  to  remove  excess  of 
acid,  dilute,  and  proceed  as  before.  1 

! 

Sulphide  of  mercury  and  substances  only  slowly  attacked  by  hydro-  j 
chloric  or  nitric  acid,  as,  for  example,  calomel  and  ignited  ferric  v 
oxide,  are  sufficiently  altered  by  the  free  chlorine  of  aqua  regia  to  ji 
become  soluble. 

If  the  substance  is  insoluble  in  water  and  acids^  it  is  one  I 
or  more  of  the  following  substances:  Sand  and  certain  |l 
silicates,  such  as  pipeclay  and  other  cla3's  ; fluor  s^iar ; ;; 
cryolite  (3NaF,AlF3);  sulphates  of  barium,  strontium,  and  •! 
possibl}"  calcium;  tinstone;  glass;  felspar  (double  silicate  : 


ANALYSIS  OF  SUBSTANCES. 


335 


of  aluminium  and  other  metals) ; chloride  of  silver ; sul- 
phate of  lead.  It  may  also  be  or  contain  carbon  or  car- 
bonaceous matter,  in  which  case  it  is  black  and  combustible, 
burning  entirely  or  partially  away  when  heated  in  the  air— 
or  be  or  contain  sulphur,  in  which  case  sulphurous  gas 
is  evolved,  detected  by  its  odor,  when  the  substance  is 
exposed  to  heat.  For  the  other  substances  proceed  accord- 
ing to  the  following  (Bloxam’s)  method  : — 

Four  or  five  grains  of  the  substance  are  intimately  mixed 
with  twice  the  quantity  of  dried  carbonate  of  sodium,  and 
this  mixture  well  rubbed  in  a mortar  with  five  times  its 
weight  of  dejiagratmg  Jiux  (1  of  finely  powdered  charcoal 
to  6 of  nitre).  The  resulting  powder  is  placed  in  a thin 
porcelain  dish,  or  crucible,  or  clean  iron  tray,  and  a lighted 
match  applied  to  the  centre  of  the  heap.  Deflagration 
ensues,  and  decomposition  of  the  various  substances 
occurs,  the  acidulous  radicals  going  to  the  alkali-metals 
to  form  salts  soluble  in  water,  the  basylous  radicals  being 
simultaneously  converted  into  carbonates  or  oxides.  The 
mass  is  boiled  in  water  for  a few  minutes,  the  mixture  fil- 
tered, and  the  residue  well  washed.  The  filtrate  may  then 
be  examined  for  acidulous  radicals  and  aluminium,  and  the 
residue  dissolved  in  dilute  hydrochloric  acid  and  analyzed 
by  the  ordinary  method. 

The  only  substance  which  resists  this  treatment  is  chrome-iron-ore. 

To  detect  alkali  in  felspar,  glass,  or  cryolite,  Bloxam  recommends 
deflagration  of  the  powdered  mineral  with  one  part  of  sulphur  and 
six  of  nitrate  of  barium.  The  mass  is  boiled  in  water,  the  mixture 
filtered,  hydrate  and  carbonate  of  ammonium  added  to  remove 
barium,  the  mixture  again  filtered,  and  the  filtrate  evaporated  and 
examined  for  alkalies  by  the  usual  process. 


QUALITATIVE  ANALYSIS  OF  SUBSTANCES 
HAVING  UNKNOWN  PEOPERTIES. 


Substances  are  presented  to  the  analyst  in  one  of  the  three  forms 
in  which  all  matter  exists — namely,  solid,  liquid,  or  gaseous. 

The  method  of  analysis  in  the  case  of  solid  bodies  has  just  been 
described  (pp.  329-35). 

In  the  case  of  liquids^  the  solvents  as  well  as  the  dis- 
solved matters  claim  attention.  A few  drops  are  evapo- 
rated to  dryness  on  platinum  foil  to  ascertain  if  solid  mat- 


33f>  GENERAL  QUALITATIVE  ANALYSTS. 

ter  of  any  kind  is  present ; the  liquid  is  tested  by  red  and 
blue  litmus  paper  to  ascertain  if  free  alkalies,  free  acids,  or 
neither  are  present ; a few  drops  are  heated  in  a test-tube 
and  the  odor  of  any  vapor  noticed,  a piece  of  glass  tubing 
bent  to  a right  angle  being,  if  necessary,  adapted  to  the 
test-tube  by  a cork,  and  some  of  the  distilled  liquid  collected 
and  examined ; finally,  the  usual  group-reagents  for  the 
several  basylous  and  acidulous  radicals  are  consecutively 
applied. 

Proceeding  in  this  way,  the  student,  who  has  already  had  some 
experience  in  pharmacy,  will  not  be  likely  to  overlook  such  solvents 
as  water,  acids,  alcohol,  ether,  fixed  oils,  and  essential  oils,  or  to  miss 
the  substances  which  these  menstrua  may  hold  in  solution.  He  must 
not,  however,  suppose  that  he  will  always  be  able  to  qualitatively 
analyze,  say,  a bottle  of  medicine ; for  the  various  infusions,  decoc- 
tions, tinctures,  wines,  syrups,  liniments,  confections,  extracts,  pill- 
masses,  and  powders  contain  vegetable  matters,  most  of  which  at 
present  are  quite  beyond  the  reach  of  the  analyst.  Neither  the 
highest  skill  in  analysis  nor  the  largest  amount  of  experience  con- 
cerning the  odor,  appearance,  taste,  and  uses  of  drugs  is  sufficient 
for  the  detection  of  all  these  vegetable  matters.  Skill  and  expe- 
rience combined,  however,  will  do  much,  and  in  most  cases  even  so 
difficult  a task  as  the  one  just  mentioned  be  accomplished  with 
reasonable  success.  Qualitative  analysis  alone  will  not  enable  the 
experimenter  to  produce  a mixture  of  substances  similar  to  that 
analyzed  ; to  this  end  recourse  must  be  had  to  quantitative  analysis, 
a subject  reserved  for  subsequent  consideration. 

Gas-analysis,  or  Eudiometry  (from  svhia,  eudia,  calm  air,  and 
fietpov,  metron,  a measure,  in  allusion  to  the  eudiometer,  an  instru- 
ment used  in  measuring  the  proportion  and,  as  the  early  chemists 
thought,  the  salubrity  of  the  gases  of  the  air),  is  a branch  of  experi-tj 
mental  investigation,  chiefly  of  a quantitative  character,  concerning 
which  information  must  be  sought  in  other  treatises.  The  analysis 
of  atmospheric  air  from  various  localities,  coal-gas,  and  gases  obtained 
in  chemical  researches,  involves  operations  which  are  scarcely  within 
the  sphere  of  Chemistry  applied  to  Medicine.  Beyond  the  recogni- 1 
tion,  therefore,  of  oxygen,  hydrogen,  nitrogen,  carbonic,  sulphurous,! 
and  hydrosulphuric  acid  gases,  the  experimental  consideration  of  the 
chemistry  of  gaseous  bodies  may  be  omitted.  Their  study,  however, 
should  not  be  neglected,  as  existing  conceptions  of  the  constitution 
of  chemical  substances  are  largely  dependent  on  the  observed  rela- 1 
tions  of  the  volumes  of  gaseous  compounds  to  their  elements.  Tlie  l 
best  work  on  this  subject  is  a small  book  by  Hofmann,  ‘ Introduction  I 
to  Modern  Chemistry.’  ■ 

Spectral  Analysis. — It  may  be  as  well  to  state  here  that  the  pre- ' 
liminary  and  final  examinations  of  minute  quantities  of  solid  matter 
may,  in  certain  cases,  profitably  include  their  exposure  to  a tempera-  : 
ture  at  which  they  emit  light,  the  flame  being  physically  analyzed  ; 
by  a spectroscope.  A spectroscope  consists^ssentially  of  a prism  to  i 
decompose  a ray  of  light  into  its  constituent  colors,  with  tubes  and  ? 


SPECTRAL  ANALYSIS. 


337 


lenses  to  collect  and  transmit  the  ray  or  rays  to  the  eye  of  an  observer. 
The  material  to  be  examined  is  placed  on  the  end  of  a platinum  wire, 
which  is  then  brought  within  the  edge  of  a spirit-lamp  or  other 
smokeless  flame ; volatilization,  attended  usually  in  the  case  of  a 
compound  by  decomposition,  at  once  occurs,  and  the  whole  flame  is 
tinged  with  a characteristic  hue.  A flat  ribbon  of  rays  is  next  cut 
off  by  bringing  near  to  the  flame  a brass  tube,  the  cap  of  which  is 
pierced  by  a narrow  slit.  At  the  other  end  of  the  tube,  at  focal  dis- 
tance for  parallel  rays,  is  a lens,  through  which  the  ribbon  of  light 
passes  to  a prism ; the  prism  decomposes  the  ribbon,  spreading  out 
its  constituent  colors  like  a partially  opened  fan,  and  the  colored 
beam  or  spectrum  thus  produced  is  then  examined  by  help  of  a tele- 
scope attached  by  a movable  joint  to  the  stand  which  carries  the 
prism  and  object-tube.  Sodium  compounds,  under  these  circum- 
stances, give  yellow  light  only,  indicated  by  a double  band  of  light 
in  a position  corresponding  to  the  yellow  part  of  an  ordinary  solar 
spectrum.  The  potassium  spectrum  is  mainly  composed  of  a red  and 
violet  band  ; lithium  a crimson,  and  at  very  high  temperatures  a 
blue  band.  Most  of  the  other  elements  give  equally  characteristic 
spectra. 


QUESTIONS  AND  EXERCISES. 

649.  Describe  the  preliminary  treatment  to  which  a salt  may  be 
subjected  prior  to  systematic  analysis. 

650.  Mention  substances  which  might  be  recognized  by  smell. 

651.  Which  classes  of  salts  are  heavy,  and  which  light  ? 

652.  Name  some  bodies  detectable  by  their  color. 

653.  What  inference  may  be  drawn  from  the  appearance  of  steam 
when  dry  substances  are  heated  ? 

654.  Why  do  certain  crystals  decrepitate  ? 

655.  If  a powder  sublimes  on  being  heated,  to  what  classes  of 
compounds  may  it  belong  ? 

656.  When  heat  causes  charring,  what  conclusion  is  drawn  ? 

657.  No  change  occurring  by  heat,  which  substances  cannot  be 
present  ? 

658.  Give  examples  of  salts  which  are  identified  by  their  reaction 
with  strong  sulphuric  acid ; by  their  comportment  in  the  blowpipe- 
flame,  with  or  without  borax  or  microcosmic  salt. 

659.  What  are  the  solvents  usually  employed  in  endeavoring  to 
obtain  a substance  in  a state  of  solution,  and  what  is  the  order  of 
their  application  ? 

660.  Name  a few  salts  which  may  be  present  in  an  aqueous  solu- 
tion. 

661.  Mention  some  common  compounds  insoluble  in  water,  but 
soluble  in  hydrochloric  acid. 

662.  What  substances  are  attacked  only  by  nitric  acid  or  nitro- 
hydrochloric  acid  ? 

i 663.  Sketch  out  a method  for  the  complete  analysis  of  a liquid  sus- 

I pected  to  be  an  aqueous  solution  of  neutral  salts. 

! 29 


338 


THE  ALKALOIDS. 


664.  How  can  earthy  phosphates  and  oxalates  with  ferric  oxide  be 
separated  from  each  other  ? 

665.  By  what  process  may  substances  insoluble  in  water  or  acids 
be  analyzed  ? 

666.  How  are  different  solvents  recognized? 

667.  By  what  methods  would  you  attempt  the  analysis  of  a bottle 
of  medicine  ? 

668.  Give  a short  sketch  of  spectral  analysis. 


CHEMISTRY  OF  CERTAIN  SUBSTANCES 
OF  VEGETABLE  AND  ANIMAL 
ORIGIN. 

Except  alcohol  and  a few  acids,  the  compounds  which  have  hitherto 
engaged  notice  have  been  of  mineral  origin.  But  the  two  other  , 
kingdoms  of  nature,  the  animal  and  vegetable,  furnish  a large  num- 
ber of  medicinal  substances.  These,  indeed,  when  discovered,  were 
producible  only  by  highly  organized  living  structures,  and  were  hence 
termed  organic  compounds.* 

A few  of  these  compounds,  of  common  occurrence  in  pharmacy  and 
possessing  prominent  characteristics,  may  now  occupy  attention ; 
reactions  of  the  alkaloids  and  some  other  principles  may  be  per- 
formed, and  the  methods  of  examining  morbid  urine  be  experimentally 
studied.  There  will  then  remain  to  be  studied  certain  galenical,  as 
distinguished  from  chemical,  substances,  solid  and  liquid,  which  can 
only  be  fairly  regarded  from  a pharmacist’s  point  of  view,  and  a still 
larger  number,  doubtless,  not  yet  brought  within  the  grasp  of  the 
chemist,  and  of  which,  therefore,  we  must  at  present  be  content  to 
remain  in  ignorance.  An  opportunity,  however,  will  be  afforded  of  i 
noticing  the  effect  of  a mixture  of  definite  and  indefinite  organic  mat- 
ter, such  as  a vomit  or  the  contents  of  a stomach,  in  masking  or  pre- 
venting the  reaction  by  which  mineral  and  vegetable  poisons  are  i 
detected. 


ALKALOIDS.  j' 

Constitution  of  Alkaloids  or  Organic  Bases.  | 

The  alkaloids,  or  alkali-like  (ftSoj,  eidos,  likeness)  bodies  have  ii 
many  analogies  with  ammonia.  Their  constitution  is  not  yet  knoMii ; ji 

* Organic^  from  opyavov^  organon^  an  organ.  A large  numV»er  of  or-|j 
gallic  compounds  can  now  be  obtained  artificially — without  the  aid  i i 
of  a living  organism:  hence  the  distinction  fuimerly  drawn  between  ;• 
organic  and  inorganic  compounds,  organic  and  inorganic  chemistry,  'i 
is  fast  breaking  down. 


NOMENCLATURE. 


339 


but  they  are  probably  derivative  of  a single  molecule  of  ammonia 
(NH3),  or  of  double,  triple,  or  quadruple  molecules  (N2H(.,  N3H9, 
N4H12).  A large  number  of  artificial  alkaloids  or  organic  bases 
having  such  a constitution  have  already  been  formed.  Those  are 
termed  amines,  and  are  primary,  secondary,  and  tertiary  according 
as  one,  two,  or  three  atoms  of  hydrogen  in  ammonia  (the  tri-hydro- 
gen  amine)  have  been  displaced  by  radicals;  as  seen  in  the  following 
general  formulae  (R  = any  univalent  radical.  Vide  Index,  “ Alcohol 
radicals’’) — 


R) 

R 

H In 

R 

h] 

H 

R) 

R \ N; 
R ) 


or  the  following  examples — 


H 
H 

Etliylamine 
or  ethylia. 


N 


N 


C,H 

H 

Diethylamine 
or  diethylia. 


N 


0,H, 

0,11, 
Triethylaiaine 
or  tryethylia. 


The  three  classes  have  also  been  termed  amidogen-,  imidogen-,  and 
nitrile-bases.  Propylamine  or  trytylia  (C3H7HHN)  is  a volatile  oil, 
one  of  the  products  resulting  from  the  destructive  distillation  of  bones 
and  other  animal  matters. 

The  displacing  radicals  may  be  similar  or  different ; and,  while  the 
radical  displacing  one  atom  of  hydrogen  is  keeping  its  place,  any  of 
the  many  known  radicals  may  occupy  the  position  of  one  or  both  of 
the  other  atoms  of  hydrogen.  Thus,  for  example,  we  have  methyl- 
etliyl-amyl-amine  (CH3C2H5C5H11N,  or  MeEtAyN),  a colorless,  oily 
body,  of  agreeable  aromatic  odor. 

The  organic  bases  derived  from  one  molecule  of  ammonia  are 
termed  monamines ; from  two  molecules,  diamines ; from  three,  tria- 
mines ; and  from  four,  tetramines  : — 


R] 

R2) 

R,) 

R In 

R^N, 

R3IN3 

rJ 

Rj 

Ra) 

Raf 

In  these  amines  any  bivalent,  trivalent,  or  quadrivalent  radical  may 
occupy  the  place  of  two,  three,  or  four  univalent  radicals. 

Attempts  to  form  artificially  the  natural  organic  bases  have  hitherto 
failed ; but  the  primary,  secondary,  or  tertiary  character  of  some  of 
them  has  been  indicated  by  the  introduction  or  elimination  of  methyl, 
ethyl,  and  other  radicals  for  hydrogen. 

Note  on  Nomenclature. — The  first  syllables  of  the  names  of  the 
natural  alkaloids  recall  the  name  of  the  plant  whence  they  were  ob- 
tained, or  some  characteristic  property.  It  is  to  be  regretted  that 
the  last  syllable  is  not  either  ine  or  ia,  instead  of  sometimes  one  and 
sometimes  the  other:  general  usage  seems  to  be  in  favor  of  the  lat- 
ter, a plan  that  distinguishes  the  alkaloids  from  some  other  sub- 
stances the  names  of  which  end  in  ine,  as  chlorine,  bromine,  iodine, 
fluorine,  glycerine,  gelatine,  etc.  The  names  of  the  salts  of  the  alka- 
loids are  given  on  the  assumption  that  the  acid  unites  with  the  alka- 


340 


THE  ALKALOIDS. 


loid  without  decomposition.  Thus  hydrochlorate  of  morphia  is  re- 
garded as  morphia  with  hydrochloric  acid  just  as  we  might  assume 
sal-ammoniac  to  be  ammonia  (NHg)  with  hydrochloric  acid  (HCl), 
and  name  it  hydrochlorate  of  ammonia  (NH3HCI)  instead  of  chloride 
of  ammonium  (NH^Cl). 

Antidotes. — In  cases  of  poisoning  by  alkaloids,  emetics  and  the 
stomach-pump  must  be  relied  on  rather  than  chemical  agents. 
Astringent  liquids  may  be  administered,  as  tannic  acid  precipitates 
many  of  the  alkaloids  from  their  aqueous  solution,  absorption  of  the 
poison  being  thus  possibly  retarded. 


MORPHIA,  OR  MORPHINE. 

Formula  Ci^HjgNOg,  H2O.  Molecular  weight  303. 

Occurrence. — Morphia  occurs  in  opium  (the  inspissated  juice  of 
the  fruit,  Papaveris  capsulce,  of  the  White  Poppy,  Papaver  somni- 
ferum)  as  meconate  of  morphia. 

Morphia,  U.  S.  P.,  is  made  by  adding  to  infusion  of  opium  an  equal 
bulk  of  alcohol,  then  slight  excess  of  ammonia,  and  setting  aside  for 
crystalline  morphia  to  separate.  It  is  purified  by  recrystallization. 

Process  for  Hydro  chlorate. — The  hydrochlorate  Cj7Hj9N03,HCl, 
SH^O  {Morphias  Hydrochloras,  B.  P.),  occurs  in  slender  white 
acicular  crystals ; it  is  prepared  by  simply  decomposing  an  aqueous 
infusion  of  opium  with  chloride  of  calcium,  meconate  of  calcium  and 
hydrochlorate  of  morphia  being  produced.  (If  the  infusion,  which 
is  always  acid,  be  first  nearly  neutralized  by  the  cautious  addition  of 
small  quantities  of  very  dilute  solution  of  ammonia,  the  chloride 
of  calcium  then  at  once  causes  a precipitate  of  meconate  of  calcium, 
which'^an  be  filtered  off,  leaving  a colored  solution  of  hydrochlorate 
of  morphia.  On  the  large  scale — vide  B.  P. — the  details  are  some- 
what different.)  The  salt  is  partially  purified  by  crystallization 
from  the  evaporated  liquid,  then  by  treatment  of  the  solution  of 
the  impure  hydrochlorate  by  animal  charcoal,  and  lastly  by  pre- 
cipitation of  the  morphia  from  the  still  colored  liquid  by  ammonia 
and  resolution  of  the  morphia  in  hot  dilute  hydrochloric  acid;  hydro- 
chlorate of  morphia  separates  out  on  cooling.  The  process  of  U.  S.  P. 
consists  in  neutralizing  morphia  by  hydrochloric  acid.  (Morphice 
Murias,  U.  S.  P.) 

Morphias  Sulphas,  U.  S.  P.,  by  neutralizing  morphia  with  sulphu- 
ric acid. 

Process  for  Acetate. — Acetate  of  morphia  (Cj^HjgN 030.211^02) 
[Morphias  Acetas,  B.  P.  and  U.  S.  P.)  is  a white  pulverulent  salt 
prepared  by  dissolving  pure  morphia  in  acetic  acid,  the  morphia  being 
prepared  (B.  P.)  from  a solution  of  the  hydrochlorate  by  precipita- 
tion with  ammonia.  Eight  parts  of  hydrochlorate  yield  about  seven 
of  acetate. 

Both  the  hydrochlorate  and  acetate  of  morphia  are  soluble  in  water, 
but  the  solution  is  not  stable  unless  acidulated  and  containing  alco- 
hol; hence  the  official  solutions,  4 grains  in  one  ounce — 1 in  110 


MORPHIA. 


341 


[Liquor  Morphice  Hydrochloratis,  B.  P.,  and  Liquor  Morphice 
Acetatis,  B.  P.),  consist  of  three  parts  water  and  i part  rectified 
spirit,  a few  minims  per  ounce  of  hydrochloric  or  acetic  acid  being 
added.  Liquor  Morphice  Sulphatis,  U.  S.  P.,  is  a solution  in  water. 
1 in  456.  The  other  official  preparations  are  Suppositoria  Morphice, 
Trochisci  Morphice,  and  Trochisci  Morphice  et  Ipecacuanhce. 

When  a simple  but  strong  solution  of  acetate  of  morphia  in  water 
is  required  (for  hypodermic  injection)  one  part  of  the  salt,  if  recently 
made,  may  be  dissolved  in  six  parts  of  water.  If  the  acetate  of 
morphia  is  old,  it  either  will  not  dissolve,  or,  if  dissolved  by  aid  of 
warmth  and  a little  acetic  acid,  will  soon  be  re-deposited.  The 
aqueous  solution,  however  well  made,  cannot  be  kept  in  its  normal 
condition  for  any  great  length  of  time. 

Other  alkaloids  exist  in  opium.  In  the  above  process  a consider- 
able quantity  of  narcotine  (C22lI.^sN07)  remains  in  the  exhausted 
opium,  and  may  be  extracted  by  digesting  in  acetic  acid,  filtering, 
precipitating  by  ammonia,  and  crystallizing  from  alcohol.  Codeia 
(^18^21^^3)^20)  is  soluble  in  the  slight  excess  of  ammonia  em- 
ployed in  precipitating  the  morphia.  From  the  mother-liquors 
there  have  also  been  obtained  thehaia  (C19H21NO3),  papaverine 
(C2oIl2,N04),  opianine  narceia  (C23H29N09),  cryp- 

topia  (C21H23NO5),  meconine  laudanine  (C2oH2f^N04), 

codamine  ^),  pseudomorphia  (‘1),  protopine  (O20H19NO5), 

laudanosine  (C21II27NO4),  hydrocotarnine  (O12IIJ5NO3). 

Analytical  Reactions. 

First  Analytical  Reaction, — To  a minute  fragment  of  a 
salt  of  morphia  add  one  drop  of  water,  and  warm  the  mix- 
ture until  the  salt  dissolves,  then  stir  the  liquid  with  a 
glass  rod  moistened  by  a strong  neutral  solution  of  per- 
chloride  of  iron ; a dirty  blue  color  is  produced.  This 
effect  is  not  observed  in  dilute  solhtions. 

Second  Analytical  Reaction, — To  a drop  or  two  of  a strong 
solution  of  a morphia  salt  in  a test-tube  add  a minute  frag- 
ment of  iodic  acid  (HIO3,  page  263) ; iodine  is  set  free. 
Into  the  upper  part  of  the  tube  insert  a glass  rod  covered 
with  mucilage  of  starch,  and  warm  the  solution  ; dark-blue 
stareh|iodide  is  produced.  If  the  mixture  of  morphia  and 
iodic  acid  be  shaken  up  with  chloroform  or  bisulphide  of 
carbon,  a violet  solution  is  obtained. 

This  reaction  is  only  confirmatory  of  others,  as  albuminous  matters 
also  reduce  iodic  acid. 

Third  Analytical  Reaction, — To  a few  drops  of  an  aque- 
ous infusion  of  opium  add  a drop  of  neutral  solution  of 
perchloride  of  iron ; a red  solution  of  meconate  of  iron  is 
produced.  Add  solution  of  corrosive  sublimate  ; the  color 

29* 


342 


THE  ALKAJ.OIDS. 


is  not  destro3^ed  (as  it  is  in  the  case  of  snlphocyanide  of 
iron,  a salt  of  similar  tint). 

In  cases  of  poisoning  by  a preparation  of  opium,  this  test  is  almost 
as  conclusive  as  a direct  reaction  of  morphia  (the  poison  itself), 
meconic  acid  being  obtainable  from  opium  only. 

Other  Reactions, — Add  carbonate  of  sodium  to  a solu- 
tion of  a salt  of  morphia;  a white  precipitate  of  morphia 
falls,  slowly  and  of  a crj-stalline  character  if  the  solution 
is  dilute.  Collect  this  precipitate  and  moisten  it  with 
neutral  solution  of  perchloride  of  iron ; the  bluisli  tint 
above  referred  to  is  produced. Add  an  alkali  to  a solu- 

tion of  hydrochlorate  or  acetate  of  the  alkaloid  ; morphia 
is  precipitated,  soluble  in  excess  of  the  fixed  alkali,  far 

less  readily^  so  in  ammonia. Moisten  a particle  of  a 

morphia  salt  with  nitric  acid  ; an  orange-red  coloration  is 

produced. Heat  morphia  on  platinum  foil  ; it  burns 

entirely  away. 


Apomorphia  (C17HJ7NO2). 


Apomorphia  {artb,  apo,  from,  and  morphia)  is  an  alkaloid  recently 
obtained  from  morphia  by  Matthiessen  and  Wright.  It  possesses 
remarkable  physiological  effects  ; of  a grain  (in  aqueous  solution) 
injected  under  the  skin,  or  | of  a grain  taken  into  the  stomach,  is 
said  to  produce  vomiting  in  from  four  to  ten  minutes. 

Process. — Hydrochlorate  of  morphia  is  hermetically  sealed  in  a 
thick  tube  with  considerable  excess  of  hydrochloric  acid,  and  heated 
to  nearly  300^  F.  for  two  or  three  hours.  The  product  is  purified 
by  diluting  the  contents  of  the  tube  with  water,  precipitating  with 
bicarbonate  of  sodium,  and  treating  the  precipitate  with  ether  or  ^ 

chloroform. On  shaking  up  the  ethereal  or  chloroform  solution  (j 

with  a very  small  quantity  of  strong  hydrochloric  acid,  the  sides  of  i 
the  vessel  become  covered  with  crystals  of  the  hydrochlorate  of  the  { 
new  base.  These  may  be  drained  from  the  mother-liquor,  washedj 
with  a little  cold  water,  in  which  the  salt  is  sparingly  soluble,  recrys- , 
tallized  from  hot  water,  and  dried  on  bibulous  paper  or  over  sul4 
phuric  acid.  The  formula  (Cj^Hj^NO.^JdCl)  indicates  that  the  newl 
alkaloid  is  derived  from  morphia  by  alDstrnctipn  of  the  elements  of  1 
water. 


Codeia,  also,  according  to  the  same  chemists,  yields  apomorphia ^ 
by  similar  treatment,  a reaction  that  would  seem  to  indicate  that ' 
codeia  is  methyl-morphia : — 


C,,H^7CH3HN03  + HCl  = CH3CI  -f  -f 

Codeia.  Chi.  of  methyl.  Apomorphia.J 

Dr.  C.  R.  A.  Wright  has  recently  obtained  several  new  deiHva-^ 
fives  of  codeia,  r.v 


Q U I N I A . 


343 


QUESTIONS  AND  EXERCISES. 


669.  Write  some  general  formulae  of  artificial  alkaloids. 

670.  Name  the  substances  represented  by  the  following  formulae : — 


671.  What  is  the  assumed  constitution  of  the  salts  of  the  alkaloids  ? 

672.  Describe  the  treatment  in  cases  of  poisoning  by  alkaloids. 

673.  Give  the  process  for  the  preparation  of  Hydrochlorate  of 
Morphia.  In  what  form  does  morphia  occur  in  opium  ? 

674.  How  is  Acetate  of  Morphia  prepared  ? 

675.  What  plan  is  adopted  for  preventing  the  decomposition  of 
the  official  solutions  of  morphia  ? 

676.  Mention  the  analytical  reactions  of  morphia. 

677.  In  addition  to  the  reaction  of  morphia,  what  test  may  be 
employed  in  searching  for  opium  in  a liquid  or  semifluid  material  ? 

678.  How  is  apomorphia  prepared,  and  what  are  its  properties  ? 

679.  Describe  the  relation  of  morphia  to  codeia. 


QUINIA,  OR  QUININE. 

Formula  C2oH24N202,3H20.  Molecular  weight  378. 


Source. — Quinia  and  other  similar  alkaloids  exist  in  cinchona- 
bark  as  kinates.  In  the  yellow  bark  ( Cinchonoe  Flavce  Cortex,  B.  P. 
and  U.  S.  P.)  quinia  is  almost  exclusively  present ; in  the  pale  bark 
[Cinclionce  Pallidoe  Cortex,  B.  P.  and  U.  S.  P.)  cinchonia  is  equally 
characteristic ; while  in  the  red  bark  ( Cinclionce  Euhrce  Cortex, 
B.  P.  and  U.  S.  P.)  these  alkaloids  occur  in  more  nearly  equal  pro- 
portions. 

Process  for  Sulphate. — Sulphate  of  quinia  ( Quinice  Sulphas,  B. 
P.)  is  prepared  according  to  the  British  Pharmacopoeia  by  treating 
the  yellow  bark  wi^h  dilute  hydrochloric  acid,  precipitating  the  re- 
sulting solution  of  hydrochlorate  of  quinia  by  soda,  and  redissolving 
the  precipitated  quinia  in  the  proper  proportion  of  hot  dilute  sulphu- 
ric acid.  The  sulphate  crystallizes  out  on  cooling  in  silky  acicular 
crystals  containing  two  atoms  of  quinia  (2O20H24N2O2),  one  of  sul- 
phuric acid  (H2SO4),  and  seven  of  water  of  crystallization  (7H2O). 

In  the  process  of  the  United  States  Pharmacopoeia  lime 
is  used  instead  of  soda  and  the  precipitated  quinia  is  dis- 
solved in  boiling  alcohol,  the  latter  recovered  by  distilla- 
tion, the  residual  quinia  neutralized  by  diluted  sulphuric 
acid,  the  solution  treated  with  animal  charcoal,  filtered 


344 


THE  ALKALOIDS. 


while  hot,  set  aside  to  crystallize,  and  recrystallized  if 
necessaiy. 


Sulphate  of  quinia,  or,  more  correctly,  disulphate,  is  only  slightly 
soluble  in  water ; on  the  addition  of  dilute  sulphuric  acid  a neutral 
sulphate  is  formed  which  is  freely  soluble.  The  latter  salt  may  be 
obtained  in  large  rectangular  prisms,  having  a composition  expressed 
by  the  formula  The  ordinary  disulphate 

of  quinia  is  more  soluble  in  alcohol  or  alcoholic  liquids  than  in  water; 
hence  the  Tinctura  Quinice,  B.  P.,  which,  is  a sokition  (saturated  at 
550  or  60^  F.)  of  the  salt  in  tincture  of  orange-peel  (eight  grains  in 
the  ounce).  Quinia  wine  ( Vinum  Quinice,  B.  P.)  is  a solution  of 
neutral  sulphate  and  citrate  of  quinia  in  orange-wine,  made  by  dis- 
solving the  disulphate  (one  grain  in  the  ounce)  in  orange-wine  by  the 
help  of  citric  acid.  The  only  official  preparation  of  the  pure  disul- 
phate is  Pilula  Quinice,  containing  three  parts  salt  to  one  of  con- 
fection of  hips  (gum  arabic  and  honey,  U.  S.  P.).  The  remaining 
Pharmacopoeial  preparation  of  quinia  is  the  mixed  citrates  of  iron, 
ammonium,  and  quinia  [Ferriet  Quinice  Citras,  B.  P.  and  U.  S.  P.), 
the  well-known  scale  compound.  It  is  made  by  dissolving  ferric 
hydrate,  prepared  from  ferric  sulphate,  and  quinia,  prepared  from 
the  sulphate,  in  solution  of  citric  acid,  ammonia  also  being  added  : 
the  liquid,  evaporated  to  a syrupy  consistence  and  dried  in  thin 
layers  on  glass  plates,  yields  the  usual  greenish-yellow  scales  {vide 
p.  130). 

Qmmce  Valerianas,  U.  S.  P.,  is  made  by  dissolving  precipitated 
quinia  in  warm  aqueous  solution  of  valerianic  acid  and  setting  aside 
to  crystallize. 

Citrate  of  Quinia  has  the  formula  (C2oH24N202)2,H3C6H507, 


Reactions. 


First  Analytical  Reaction. — To  a soli(t^n  of  quinia  or 
its  salts  in  faintly  acid  water  add  fresh  chlorine-water  and 
then  solution  of  ammonia;  a green  coloration  (thalleiochin) 
is  produced.  According  to  Fliickiger,  in  very  dilute  solu-  | 
tions  of  quinine  bromine-vapor  is  more  useful  than  chlorine  [, 
for  this  reaction.  j 

Second  Analytical  Reaction. — Repeat  the  foregoing  re- 
action. but  precede  the  addition  of  ammonia  by  solution  of  I 
ferrocyanide  of  potassium  ; an  evanescent  red  coloration  is  i 
^produced  (Livonius  and  Vogel). 

Third  Analytical  Reaction. — Quinia  may  be  impure  from  the 
piesence  of  the  other  alkaloids  (chiefly  quinidia,  cinchoiiia)  of 
cinchona-bark ; the  following  tests  will  determine  the  point.  The  ' 
first  is  Stoddart’s  modification  of  Liebig’s  process. 


nto  a glass  tube  or  bottle  put  ten  grains  of  the  suspected  I 
It,  dissolve  in  10  minims  of  dilute  sulphuric  acid  and  60 


QU I NI A. 


345 


minims  of  distilled  water  ; to  this  add  150  minims  of  pure 
ether,  3 minims  of  spirits  of  wine,  and  40  minims  of  a solu- 
tion of  soda  (1  part  of  solid  hydrate  to  12  of  water). 
Agitate  well  and  set  aside  for  twelve  hours,  when,  if  the 
slightest  trace  of  quinidia  and  cinchonia  be  present,  they 
will  be  seen  at  the  line  of  separation  between  the  ether  and 
solution  of  sulphate  of  sodium. 

If  only  a small  percentage  of  quinidia  be  present,  it  will 
appear  as  an  oily  substratum,  appearing  under  a lens  as 
dust,  from  the  minuteness  of  its  particles.  Cinchonia  will 
appear  more  decidedlj"  crystalline.  With  a little  practice 
the  eye  will  easily  distinguish  which  of  the  alkaloids  is  de- 
posited. 

Fourth  Analytical  Beaction. — This  is  StoddarCs  chemico- 
microscopic  test.  Into  an  ounce  of  distilled  water  drop  10 
drops  of  dilute  sulphuric  acid  (British  Pharmacopoeia 
strength).  To  this  add  14  grains  (or  as  much  as  will  satu- 
rate the  acid)  of  the  suspected  salt.  Filter  through  paper, 
and  to  a little  of  the  filtered  solution  add  a few  drops  of 
solution  of  sulphocyanide  of  potassium  (180  grains  in  1^ 
ounce  of  water).  An  immediate  precipitate  of  the  several 
alkaloids  takes  place,  each  of  which  is  distinct  and  charac- 
teristic. If  quinia,  quinidia,  and  cinchonia  be  present,  they 
will  all  be  seen  on  the  slide,  becoming  more  and  more 
distinct  during  the  first  hour.  A good  plan  is  to  place  on 
a glass  slip  a drop  of  the  solution  to  be  tested,  and  to  put 
another  of  tlie  sulphocyanide  by  its  side — the  drops  not 
being  larger  than  good-sized  pin-heads.  Over  both  place 
a piece  of  thin  glass,  which  will  cause  the  drops  to  touch. 
Examine  the  line  of  junction  under  a half-inch  object-glass, 
when  the  crystals  are  readily  seen  and  recognized.  By  this 
method  xo^oo  ^ grain  of  quinidia  or  cinchonia  may  be 
easily  detected.  The  particles  arrange  themselves  into  the 
respective  groups — the  long  slender  needles  of  the  quinia 
salt,  the  round  crystalline  masses  of  the  quinidia,  and  the 
large  well-formed  prisms  of  the  cinchonia  salts.  This  re- 
action is  sufficiently  constant  to  enable  an  observer  who 
has  accustomed  himself  to  the  microscopic  appearance  of 
the  three  pure  sulphocyanides  to  at  once  distinguish  the 
respective  salts  from  each  other. 

The  sulphoc3’anide-of-potassium  solution  should  be  of  the 
strength  indicated.  If  not  at  hand  it  may  quickly"  be  made, 
sufficiently  pure  for  this  reaction,  by  the  following  process  : 
C^^anide  of  potassium  (fused),  sublimed  sulphur,  of  each 
120  grains;  distilled  water  an  ounce  and  a half.  Boil  in  a 


346 


THE  ALKALOIDS. 


glass  flask  for  fifteen  minutes,  filter,  and  make  up  the 
quantity  to  1^  ounce  with  sufficient  distilled  water. 

A small  quantity  of  quinia  in  much  cinchonia  or  quinidia 
cannot  be  recognized  by  the  above  reaction.  Therefore, 
before  concluding  that  no  quinia  is  present  in  a specimen 
of  those  alkaloids,  the  sample  should  be  treated  with  ether, 
filtered,  the  solution  evaporated  to  dryness,  and  the  residue, 
if  any,  examined  for  quinia. 

Other  Characters,  — Concentrated  sulphuric  acid  dis- 
solves quinia  with  production  of  only  a faint  yellow  color; 
salicin,  with  which  quinia  may  possibly  be  adulterated, 
slowly  gives,  under  the  same  circumstances,  a deep  red.  ^ 

Concentrated  nitric  acid  dissolves  quinia,  yielding  a | 
colorless  solution  ; on  heating,  the  solution  becomes  yel- 
lowish. 

Quinia  and  its  salts,  heated  on  platinum  foil,  burn  en- 
tirely away. 

Salicin  in  quinia  may  be  detected  by  several  other  tests 
{cide  “ Salicine^'  in  Index). 

Cinchonia  or  Cinchonine  (C.^qH.^^N.^O)  and  quinia  are  distin- 
guished from  morphia  by  non-solubility  of  the  alkaloid  precipitated 
by  a fixed  alkali  in  excess  of  the  alkaline  solution.  They  are  dis- 
tinguished from  each  other  by  the  solubility  of  the  precipitated 
quinia  and  insolubility  of  cinchonia  when  ether  is  added  to  the 
alkaline  mixture.  Cinchonia,  moreover,  does  not  give  the  green 
coloration  with  chlorine-water  and  ammonia.  Strychnia  is  also  pre- 
cipitated by  fixed  alkalies  and  insoluble  in  excess,  but  this  alkaloid 
has  such  strongly  marked  reaction  of  its  own  as  to  preclude  confusion. 

Sulphate  of  Cinchonia  ( Cinchonioe  Sulphas,  U.  S.  P.)  occurs  in 
the  mother-liquors  of  sulphate  of  quinia,  and  is  directly  prepared 
from  several  kinds  of  bark.  It  forms  white,  shining  crystals,  having 
the  form  of  short,  oblique  prisms,  with  dihedral  summits.  Like  sul- 
phate of  quinia,  when  heated,  it  fuses  to  a resinoid  mass  of  a rich 
red  color.  It  dissolves  in  fifty-four  parts  of  cold  water,  in  much  less 
boiling  water,  in  seven  parts  of  alcohol,  and  very  sparingly  in  ether. 
Its  aqueous  solution  gives  with  terchloride  of  gold  a yellow  precipi- 
tate, and  with  chloride  of  calcium  a white  one.  Ammonia,  added  to 
its  solution  in  chlorine  water,  causes  a white  precipitate.  If  the  salt 
be  rubbed  with  water  of  ammonia,  and  then  treated  with  ether,  the 
cinchonia,  separated  by  the  former,  will  not  be  dissolved  by  the 
latter. 

Quinidia  or  Quinidine  is  an  isomer  of  quinia,  and  Cinchonidia  i 
or  Cinchonidine  an  isomer  of  cinchonia.  Cinchovatia  or  Cincho-  ! 
vatine  occurs  in  a particular  variety  of  cinchona-bark.  Quinicia  or  * 
Qainicine  and  Cinchonicia  or  Cinchonicine  are  the  products  of 
the  action  of  heat  on  quinia  and  cinchonia. 


STRYCHNIA, 


34t 


STRYCHNIA,  OR  STRYCHNINE. 

Formula  O21H22N2O2.  Molecular  weight  334. 

Source. — This  alkaloid  exists  in  Nux  Yomica  [Strychnos  Nux 
Vomica,  B.  P.  and  U.  S.  P.)  and  in  St.  Ignatius’s  bean  {Strychnos 
Ignatia)  (Ignatia,  U.  S.  P.)  chiefly  in  combination  with  lactic  acid. 

Process. — According  to  the  British  official  process  for  its  prepara- 
tion [Strychnia,  B.  P.)  the  nuts,  disintegrated  by  subjection  to  steam 
and,  after  drying,  grinding  in  a coffee-mill,  are  exhausted  with  spirit, 
the  latter  removed  by  distillation,  the  extract  dissolved  in  water, 
coloring  and  acid  matters  precipitated  by  acetate  of  lead,  the  filtered 
liquid  evaporated  to  a small  bulk,  the  strychnia  precipitated  by  am- 
monia, the  precipitate  washed,  dried,  and  exhausted  with  spirit,  the 
spirit  recovered  by  distillation,  and  the  residual  liquid  set  aside  to 
crystallize.  Crystals  of  strychnia  having  formed,  the  mother-liquor 
(which  contains  the  brucia  of  the  seeds)  is  poured  away,  and  the 
crystals  of  strychnia  washed  with  spirit  (to  remove  any  brucia)  and 
recrystallized. 

In  the  U.  S.  P.  process  the  rasped  Nux  Yomica  is  exhausted  by 
very  dilute  hydrochloric  acid,  milk  of  lime  added  to  the  evaporated 
decoction  to  decompose  the  hydrochlorate  of  strychnia,  the  precipi- 
tated and  dried  mixture  of  strychnia  and  lime  treated  with  diluted 
alcohol  to  remove  brucia,  and  then  with  strong  hot  alcohol  to  dis- 
solve out  strychnia  : the  alcohol  having  been  recovered  by  distillation, 
the  residual  impure  strychnia  is  dissolved  in  very  dilute  sulphuric 
acid,  the  solution  decolorized  by  animal  charcoal,  evaporated,  and  set 
aside  to  crystallize,  the  crystals  of  sulphate  of  strychnia  [Strychnice 
Sulphas,  U.  S.  P.)  redissolved  in  water,  ammonia  added  to  precipi- 
tate pure  strychnia,  and  the  latter  dried. 

Properties. — Strychnia  occurs  ‘‘  in  right  square  octahedrons  or 
prisms,  colorless  and  inodorous ; sparingly  soluble  in  water,  but  com- 
municating to  it  its  intensely  bitter  taste  ; soluble  in  boiling  rectified 
spirit  and  in  chloroform,  but  not  in  absolute  alcohol  or  in  ether.” 

Reactions. 

First  Analytical  Beaction. — Place  a minute  particle  of 
strj’chnia  on  a white  plate,  and  near  to  it  a small  fragment 
of  red  chromate  of  potassium  ; to  each  add  one  drop  of 
concentrated  sulphuric  acid : after  waiting  a minute  or  so 
for  the  chromate  to  fairly  tinge  the  acid,  draw  the  latter, 
by  a glass  rod,  over  tlie  strychnia  spot ; a beautiful  purple 
color  is  produced,  quickly  fading  into  a yellowish-red. 
The  following  oxidizing  agents  may  be  used  in  the  place 
of  the  chromate : puce-colored  oxide  of  lead,  fragments  of 
black  oxide  of  manganese,  ferridcyanide  of  potassium,  or 
permanganate  of  potassium. 


348 


THE  ALKALOIDS. 


This  reaction  is  highly  characteristic ; a minute  fragment  dissolved 
in  much  dilute  alcohol,  or,  better,  chloroform,  and  one  drop  of  the 
liquid  evaporated  to  dryness  on  a porcelain  crucible-lid  or  other  white 
surface,  yields  a residue  which  immediately  gives  the  purple  color  on 
being  oxidized  in  the  manner  directed. 

Other  Reactions. — Strong  sulphuric  acid  does  not  act  on  strychnia, 
even  at  the  temperature  of  boiling  water,  a fact  of  which  advantage 
is  taken  in  separating  strychnia  from  other  organic  matter/for  pur- 
poses of  toxicological  analysis. Sulphocyanide  of  potassium  pro- 

duces, even  in  dilute  solutions  of  strychnia,  a w^hite  precipitate, 
which,  under  the  microscope,  is  seen  to  consist  of  tufts  of  acicular 

crystals. Strong  nitric  acid  does  not  color  strychnia  in  the  cold, 

and  on  heating  only  turns  it  yellow. 

The  Physiological  Test. — A small  frog  placed  in  an  ounce  of  water 
to  which  of  a grain  of  a salt  (acetate)  of  strychnia  is  added,  is, 
in  two  or  three  hours,  seized  with  tetanic  spasms  on  the  slightest 
touch,  and  dies  shortly  afterwards. 

Strychnia  has  an  intensely  bitter  taste.  Cold  water  dissolves 
only  part;  yet  this  solution,  even  when  largely  diluted,  is  dis- 
tinctly bitter.  Alcohol  is  a somewhat  better  solvent.  The  salts  of 
the  alkaloid  are  more  soluble.  The  official  solution  [Liquor  Strych- 
nice,  B.  P.)  contains  four  grains  of  strychnia  to  the  ounce,  the  sol- 
vent being  three  parts  water,  one  part  spirit,  and  a few  minims 
(6  per  ounce)  of  hydrochloric  acid  (rather  more  than  sufficient  to 
form  hydrochlorate  of  strychnia). 

Brucia,  or  Brucine  (C.^3H2gN204,4H20),  is  an  alkaloid  accompany- 
ing strychnia  in  Nux  Vomica.  It  is  readily  distinguished  by  the 
intense  red  color  produced  when  nitric  acid  is  added  to  it.  Igasuria 
is  another  alkaloid  of  Nux  Vomica.  This  alkaloid  is  said  to  occur 
in  no  less  than  nine  varieties,  each  slightly  differing  from  the  other 
in  chemical  composition.  They  resemble  strychnia  in  physical 
properties. 

Distinction  of  Brucia  from  Morphia. — The  red  coloration  pro- 
duced by  the  action  of  nitric  acid  on  brucia  is  distinguished  from 
that  yielded  by  morphia  by  the  action  of  reducing  agents  (such  as 
stannous  chloride,  hyposulphite  of  sodium,  sulphydrate  of  sodium), 
which  decolorize  the  morphia-red,  but  change  that  of  the  brucia  to 
violet  and  green  (Cotton). 

Distinction  of  Free  Alkaloids  or  their  Salts  from  each  Other. — 
This  is  accomplished  by  remembering  the  appearance  and  other  phy- 
sical characters  of  the  substances  as  met  with  in  pharmacy,  the  effect 
of  heat,  the  action  of  such  solvents  as  water,  alcohol,  and  ether,  the 
influence  of  strong  and  diluted  acids,  strong  and  weak  alkalies,  oxi- 
dizing agents,  chlorine-w^ater  and  ammonia,  and  other  reagents. 


QUESTIONS  AND  EXERCISES. 

680.  What  alkaloids  are  more  or  less  characteristic  of  the  different 
varieties  of  cinchona-bark  ? In  wdiat  form  do  they  occur  ? 

681.  By  wffiat  method  is  Disulphate  of  Quinia  obtained? 


I: 


ACONITI A. 


349 


682.  Give  the  characters  of  disulphate  of  quinia. 

683.  Describe  the  tests  for  quinia. 

684.  How  is  the  adulteration  of  disulphate  of  quinia  by  salicin 
detected? 

685.  Show  how  the  sulphates  of  quinidia  or  cinchonia  maybe  proved 
to  be  present  in  commercial  quinia. 

686.  How  are  cinchonia  and  quinia  distinguished  from  morphia  ? 

687.  Whence  is  strychnia  obtained  ? 

688.  Describe  the  official  process  for  the  isolation  of  strychnia. 

689.  Give  the  characters  of  strychnia. 

690.  Enumerate  the  tests  for  strychnia,  and  describe  their  mode 
of  application. 

6^.  By  what  reagent  is  brucia  distinguished  from  strychnia? 

692.  Distinguish  between  brucia  and  morphia. 

693.  By  what  general  methods  would  you  distinguish  common 
alkaloids  from  each  other  ? 


ALKALOIDS  OF  LESS  FREQUENT  OCCURRENCE. 

Aconitia,  Aconitina,  or  Aconitine  (G^qH^^NO^)  is  an  alkaloid 
obtained  from  aconite  [Aconitum  Napellus)  leaves  (.Aconiti  Folia^ 
B.  P.  and  U.  S.  P.)  and  root  [Aconiti  Radix,  B.  P.  and  U.  S.  P.). 
The  alkaloid  itself  is  only  slightly  sqluble  in  water ; it  occurs  in  the 
plant  in  combination  with  a vegetable  acid,  forming  a soluble  salt. 

P/  'ocess, — The  official  process  for  its  preparation  [Aconitia,  B.  P. 
and  U.  S.  P.)  consists  in  dissolving  out  the  natural  salt  of  the  alka- 
loid from  the  root  by  rectified  spirit,  recovering  the  latter  by  distilla- 
tion, mixing  the  residue  with  water,  filtering,  precipitating  the  aco- 
nitia by  ammonia,  drying  the  precipitate  and  digesting  it  in  ether 
(in  which  some  of  the  accompanying  impurities  are  insoluble),  recover- 
ing the  ether  by  distillation,  dissolving  the  dry  residue  in  the  retort 
in  water  acidulated  by  sulphuric  acid,  again  precipitating  the  alka- 
loid by  ammonia,  and  finally  washing  and  drying. 

Properties. — Aconitia  usually  occurs  as  a white  powder,  but  has 
been  obtained  and  studied  in  the  crystalline  state  by  Groves  and  by 
Duquesnel.  It  is  soluble  in  150  parts  of  cold  water,  50  of  hot,  and 
much  more  soluble  in  alcohol  and  in  ether.  It  is  one  of  the  most  vio- 
lent poisons  known.  “ When  rubbed  on  the  skin  it  causes  a tingling 
sensation,  followed  by  prolonged  numbness.” 

The  thousandth  part  of  a grain  on  the  tip  of  the  tongue  produces, 
after  a minute  or  so,  a characteristic  tingling  sensation  and  numb- 
nOvSs ; larger  quantities  rubbed  into  the  skin  cause  numbness  and  loss 
of  feeling.  To  a strong  solution  of  phosphoric  acid  (the  ordinary  acid 
concentrated  over  a water-bath  to  a syrupy  consistence)  a mere  trace 
imparts  a lasting  violet  tint  (Fluckiger).  Oil  of  vitriol  turns  it  of  a 
yellowish,  and  afterwards,  dirty  violet  color. 

Several  alkaloids  have  been  obtained  from  different  species  and 
varieties  of  aconite.  They  are  under  research  by  chemists. 

Unguentum  Aconitice,  B.  P.,  contains  eight  grains  of  the  alkaloid 
to  one  ounce  of  prepared  lard. 

30 


350 


THE  ALKALOIDS. 


Atropia,  or  Atropine  (Cj^Hg^NOg),  exists  in  the  Belladonna,  or 
Deadly  Nightshade  [Atropa  Belladonna:  Belladonnce  Folia  et 
RadiXy  B.  P.  and  U.  S.  P.),  as  soluble  acid  malate  of  atropia. 

Process. — It  is  obtained  in  the  pure  state  by  exhausting  the  root 
with  spirit,  precipitating  the  acid  and  some  coloring-matter  by  lime, 
filtering,  adding  sulphuric  acid  to  form  sulphate  of  atropia  (which  is 
somewhat  less  liable  to  decomposition  during  subsequent  operations 
than  the  alkaloid  itself),  recovering  most  of  the  spirit  by  distillation, 
adding  water  to  the  residue,  and  evaporating  till  the  remaining  spirit 
is  removed  ; solution  of  carbonate  of  potassium  is  then  poured  in  till 
the  liquid  is  nearly  but  not  quite  neutral,  by  which  resinous  matter 
is  precipitated;  the  latter  is  filtered  away,  excess  of  carbonate  of 
potassium  then  added,  and  the  liberated  atropia  dissolved  out  by 
shaking  the  liquid  with  chloroform.  The  latter  solution,  having  sub- 
sided, is  removed,  the  chloroform  recovered  by  distillation,  the  residual 
atropia  dissolved  in  warm  spirit,  coloring  matter  separated  by  digest- 
ing the  liquid  with  animal  charcoal,  the  solution  filtered,  evaporated, 
and  set  aside  to  deposit  crystals. 

Soliihility. — Atropia  is  sparingly  soluble  in  water,  the  liquid  giving 
an  alkaline  reaction — more  soluble  in  alcohol  and  ether. 

Tests. — Atropia-solutions  give  with  perch loride  of  gold  a yellow 
precipitate.  One  drop  of  a dilute  aqueous  solution  (two  grains  to 
the  ounce)  powerfully  dilates  the  pupil  of  the  eye.  It  is  applied  on 
a piece  of  thin  tissue  paper  or  spall  disk  placed  between  the  eyelid 
and  the  eye. 

Preparations. — The  alkaloid  itself  {Atropia),  its  sulphate  {Atro- 
pice  Sulphas,  a colorless  powder  soluble  in  water,  made  by  neutral- 
izing atropia  with  sulphuric  acid),  their  solutions  (Liquor  Atropice, 
four  grains  per  ounce,  and  Liquor  Atropice  Sulphatis,  four  grains 
per  ounce),,  and  an  ointment  ( Unguenturri  Atropice,  eight  grains  per 
ounce)  are  the  preparations  official  in  the  British  Pharmacopoeia. 
The  alkaloid  and  its  sulphate  are  official  in  the  United  States  Phar- 
macopoeia. 

Datxirjia  or  Daturine,  an  alkaloid  in  Datura  Stramonium  or 
Thorn-apple  (Stramonii  Folia  et  Semina,  B.  P.  and  U.  S.  P.), 
appears  to  be  identical  with  atropia. 

Beberia,  or  Beberine  (C^yH^^NOg),  is  an  alkaloid  existing  in  the 
bark  of  Bebeeru  (Nectandra  Rodicei). 

Process. — According  to  the  British  Pharmacopoeia,  it,  or  rather 
its  sulphate,  CggH^.^N.^Og,  H2SO4  (Beherice  Sulp)has,  B.  P.),  may  be 
prepared  by  exhausting  the  bark  (Nectandrce  Cortex,  B.  P.  and  U. 
S.  P.)  with  water  acidulated  by  sulphuric  acid,  concentrating,  remov- 
ing most  of  the  acid  by  lime,  filtering,  precipitating  the  alkaloid  by 
ammonia,  filtering,  drying,  dissolving  in  spirit  (in  which  some  accom- 
panying matters  are  insoluble),  recovering  most  of  the  spirit  by 
distillation,  neutralizing  by  dilute  sulphuric  acid,  evaporating  to  dry- 
ness, dissolving  the  residual  sulphate  in  water,  evaporating  to  the 
consistence  of  a syrup,  and  spreading  on  glass  plates,  drying  the  pro- 
duct at  140^.  Thus  obtained,  it  occurs  in  thin  dark-brown  translu- 
cent scales,  yellow  when  powdered,  strongly  bitter,  soluble  in  water 
and  in  alcohol. 


BERBERIA  — CONIA. 


351 


Tests. — Alkalies  give  a pale  yellow  precipitate  of  beberia  when 
added  to  an  aqueous  solution  of  a salt  of  the  alkaloid ; the  precipi- 
tate is  soluble  in  ether.  With  red  chromate  of  potassium  and  sul- 
phuric acid  beberia  gives  a black  resin,  and  with  nitric  acid  a yellow 
resin. 

Nectandria  (C20H23NO4). — Drs.  Maclagan  and  Gamgee  have  re- 
cently discovered  this  second  alkaloid  in  Bebeeru  bark.  It  differs 
from  beberia  in  fusing  when  placed  in  boiling  water,  in  being  much 
less  soluble  in  ether,  in  giving  with  strong  sulphuric  acid  and  black 
oxide  of  manganese  a beautiful  green  and  then  violet  coloration, 
and  in  having  a distinct  molecular  weight.  They  are  of  opinion 
that  two  other  alkaloids  exist  in  Bebeeru  bark. 

Berberia,  or  Berberine  (C2oHi7N04),  is  an  alkaloid  existing  in 
several  plants  of  the  natural  order  Berberidece,  in  Calumba-root 
( Calumbce  Radix,  B.  P.  and  U.  S.  P.),  Goldthread  ( Coptis  trifolia, 
U.  S.  P.)  according  to  Mayer,  and  in  many  yellow  woods.  The  color 
of  the  tissues  of  these  vegetables  is  apparently  due  to  berberia;  for 
the  alkaloid  itself  is  remarkable  for  its  beautiful  yellow  color. 

Tests. — When  a dilute  solution  of  iodine  in  iodide  of  potassium  is 
added  to  solution  of  any  salt  of  berberia  in  hot  spirit,  excess  of 
iodine  being  carefully  avoided,  brilliant  green  spangles  are  deposited. 
The  reaction  is  sufficiently  delicate  to  form,  according  to  Perrins,  an 
excellent  test  of  the  presence  of  berberia.  This  iodo-compound 
polarizes  light,  and  has  other  analogies  with  a similar  quinine-salt 
termed  herapathite. 

Berberia  is  not  an  official  alkaloid ; but  the  plants  in  which  it 
occurs  are  used  as  medicinal  agents  in  all  parts  of  the  world. 

Process. — Berberia  is  readily  extracted  by  boiling  the  raw  material 
with  water,  evaporating  the  strained  liquid  to  a soft  extract,  digest- 
ing the  residue  in  alcohol,  recovering  the  alcohol  by  distillation, 
boiling  the  residue  with  diluted  sulphuric  acid,  filtering  and  setting 
aside ; the  sulphate  of  berberia  separates  out,  and  may  be  purified 
by  recrystallization  from  hot  water.  The  alkaloid  itself  is  obtained 
by  shaking  hydrate  of  lead  with  a hot  aqueous  solution  of  the  sul- 
phate of  berberia  (Procter). 

Podophyllum-voot  [Podopliylli  Radix,  B.  P.,  Podophyllum, 
U.  S.  P.),  contains  berberia.  In  preparing  the  resin  of  podophyllum 
or  May-apple  [PodopjJiylli  Resina,  B.  P.  and  U.  S.  P.)  an  alcoholic 
extract  of  the  root  is  poured  into  water  acidulated  by  hydrochloric 
acid,  whereby  the  whole  of  the  hydrochlorate  of  berberia,  which  is 
almost  insoluble  in  dilute  mineral  acids,  is  precipitated  with  the  resin 
(Maisch).  No  acid  is  ordered  in  U.  S.  P. 

Capsicia,  or  Capsicine,  is  an  alkaloid  occurring  in  Cayenne  pep- 
per or  Capsicum-fruit  [Capsid  Fructus,  B.  P.  and  U.  S.  P.),  asso- 
ciated with  resin  and  volatile  oil.  It  is  crystalline,  and  forms  crys- 
tallizable  salts  with  acids. 

CiSSAMPELIA,  CiSSAMPELINE,  PeLOSIA,  Or  PeLOSINE  (CjgH.^jNOg), 
is  an  alkaloid  occurring  in  the  root  [Pareirce  Radix,  B.  P.  and 
U.  S.  P.)  of  Cissampdos  Pareira.  It  is  the  tonic  and  diuretic 
principle  of  the  drug. 

Conia,  Conylia,  Conine,  Conicine,  or  Cicutine.  — Formula 


352 


THE  ALKALOIDS. 


CgH^^N,  or  (CgHj4)"HN.  This  alkaloid  is  a volatile  liquid,  occur- 
ring in  hemlock  ( Conium  maculcvtum).  It  is  not  official. 

Process. — It  may  be  obtained  by  distilling  hemlock-fruit  ( Conii 
Fructtis,  B.  P.)  with  water  rendered  slightly  alkaline  by  caustic 
soda  or  potash,  or  by  similarly  treating  the  fresh  juice  of  the  leaves. 
The  alkaloid  is  a yellow  oily  liquid,  floating  on  the  water  that  distils 
over ; by  redistillation  it  is  obtained  colorless  and  transparent. 

The  salts  of  conia  have  no  odor,  but  when  moistened  wdth  solu- 
tion of  an  alkali  yield  the  alkaloid,  the  strong  smell  of  wffiich,  at  once 
recalling  hemlock,  is  characteristic.  Extract  of  hemlock  leaves 
( Conii  Folia,  B.  P.  and  U.  S.  P.),  to  which  solution  of  potash  and 
boiling  water  have  been  added,  forms  the  official  Inhalation  of  Conia 
(Vapor  Conice,  B.  P.). 

Tests. — Sulphuric  acid  turns  conia  purplish-red,  changing  to  olive- 
green,  nitric  acid  a blood-red ; perchloride  of  gold  produces  a yel- 
lowish-white preeipitate,  perchloride  of  platinum  no  precipitate,  in 
aqueous  solutions. 

Hemlock  also  contains  methyl-conia  (CgHiJ^CngN  (Kekule  and 
Yan  Planta). 

According  to  SchifF,  conia,  isomeric,  at  least,  wdth  the  natural  alka- 
loid, may  be  produced  artificially  by  action  of  ammonia  on  butyric 
aldehyd  and  destructive  distillation  of  the  resulting  compound. 

Daturia,  or  Daturine,  vide  Atropia. 

Emetia,  or  Emetine  (C3oH44N20g). — This  alkaloid  is  the  active 
emetic  principle  of  Cephcelis  ipecacuanha  (Ipecacuanha.  B.  P.  and 
U.  S.  P.).  It  occurs  in  combination  with  ipecacuanhic  acid.  The 
nitrate  is  peculiarly  slightly  soluble  in  water  (Lefort).  In  the  Pul- 
vis  Ipecacuanhce,  B.  P.  and  U.  S.  P.,  or  ‘‘Dover’s  Powder”  (Pow- 
dered Ipecacuanha,  1 part : Powdered  Opium,  1 part ; and  Sulphate 
of  Potassium,  8 parts),  minute  division  of  the  active  ingredients  is 
promoted  by  prolonged  trituration  with  sulphate  of  potassium,  which 
is  a very  hard  salt. 

Hyosciamia,  or  Hyosyamine  (CigH2g,N203;  other  authors, 
CJ5H23NO3),  a volatile  alkaloid,  is  said  to  occur  in  the  leaves  (Hyos- 
cyami  Folia,  B.  P.  and  U.  S.  P.,  Hyoscyami  Semen,  V . S.  P.),and 
other  parts  of  Henbane.  Its  effect  on  the  eye  is  similar  to  that  of 
atropia. 

Lobelia,  or  Lobeline, — A volatile  alkaloid  first  isolated  from  the 
dried  flowering  herb  Lobelia  inflata  (Lobelia,  B.  P.  and  U.  S.  P.) 
by  Bastick.  In  the  pure  state  it  smells  slightly  of  the  plant,  but 
mixed  with  ammonia  it  emits  a strong  and  characteristic  smell  of  the 
herb. 

Nectandria,  vide  Beberia. 

Nicotia,  Nicotina,  Nicotylia,  or  Nicotine. — Formula  CjoHj^Nk^, 
or  (L5H7)'”2N2.  This  is  also  a volatile  liquid  alkaloid,  forming  the 
active  principle  of  tobacco  (Nicotiana  tabacum),  malate  and  ci- 
trate of  nicotina  being  the  forms  in  which  it  occurs  in  the  leaf 
( Tabaci  Folia,  B.  P.  and  U.  S.  P.).  Its  odor  is  characteristic ; like 
conia,  it  yields  a precipitate  with  perchloride  of  gold ; but,  unlike 
that  alkaloid,  its  aqueous  solutions  are  precipitated  yellowish-white 
by  perchloride  of  platinum.  It  is  not  official. 


PHYSOSTTGMIA  — THEIA. 


353 


Physostigmia,  or  Physostigmine. — An  alkaloid  contained  in  the 
Calabar  Bean  [Physostigmatis  Faba),  the  seed  of  Pliysostigma 
venenosum  (Jobst  and  Hesse).  A trace  of  it  powerfully  contracts 
the  pupil  of  the  eye ; a small  quantity  is  highly  poisonous.  Fraser 
also  isolated  this  principle,  and  termed  it  Eseria,  from  Esere,  the 
name  of  this  ordeal-poison  at  Calabar. 

PiPERiA,  or  PiPERiNE  (Ct7Hj9N03),  is  a feeble  alkaloid  occurring 
in  white,  black  [Piper  Nigrum,  B.  P.  and  U.  S.  P.),  long,  and  cu- 
beb  pepper  (Cubeba,  B.  P.  and  U.  S.  P.),  associated  with  volatile 
oil  and  resin  ; to  these  three  substances  the  odor,  flavor,  and  acridity 
belong.  Piperia  is  obtained  on  boiling  white  pepper  with  alcohol, 
and  evaporating  the  liquid  with  solution  of  potash,  which  retains  re- 
sin. Eecrystallized  from  alcohol,  piperia  forms  colorless  prisms  fusi- 
ble at  2120.  With  acids  it  forms  salts,  and  distilled  with  strong 
alkali  yields  piperidia  or  piperidine,  an  alkaloid  of  strong  chemical 
properties. 

Sanguinarina,  or  Sanguinarine  (C37Hj,^N40g),  is  a colorless  alka- 
loid obtained  from  the  rhizome  of  Sanguinaria  Canadensis  (U.  S. 
P.)  or  Blood-root.  Its  salts  have  a red,  crimson,  or  scarlet  color. 

SoLANiA,  or  SoLANiNE  (C^gH^oNOig). — An  alkaloid  said  to  exist  in 
the  Woody  Nightshade  or  Bitter-sweet  [Solanum  dulcamara).  The 
dried  young  branches  of  the  plant  are  official  [Dulcamara,  B.  P. 
and  U.  S.  P.).  The  alkaloid  is  only  slightly  soluble  in  water,  alco- 
hol, or  ether;  nitric  acid  colors  it  yellow;  sulphuric  acid  produces 
at  first  a yellow,  then  a violet,  and  finally  a brown  coloration. 

Sparteia,  or  Si»arteine  (C|5H26N),  is  a poisonous  volatile  alka- 
loid occurring  in  Broom-tops  [Scoparii  Cacumina,  B.  P.  and  U.  S. 
P.).  Its  discoverer,  Stenhouse,  considers  that  the  diuretic  principle 
of  broom  is  Scoparin,  a n on-poisonous  body. 

Theia,  Theine,  or  Caffeine  (CgHjoN^02-hH20). — This  alkaloid 
occurs  in  tea,  coffee  [Caffea,  U.  S.  P.),  Paraguay  tea,  guarana,  and 
the  kola-nut.  Infusions  and  preparations  of  these  vegetable  pro- 
ducts ai*e  used  chiefly  as  beverages  by  three-fourths  of  the  human 
race.  It  is  remarkable  that  the  instinct  of  man,  even  in  his  savage 
state,  should  have  led  him  to  select,  as  the  bases  of  common  bever- 
ages, just  the  four  or  five  plants  which  out  of  many  thousands  are 
the  only  ones,  so  far  as  we  know,  containing  theia.  Theia  is  volatile. 
Large  quantities  may  be  collected  by  condensing  the  vapors  evolved 
during  the  roasting  of  coffee  on  the  large  scale.  The  infusion  of  tea, 
from  which  astringent  and  coloring-matters  have  been  precipitated 
by  solution  of  subacetate  of  lead,  and  which  has  been  evaporated  to 
a small  bulk,  yields  a precipitate  of  theia  on  the  addition  of  a strong 
solution  of  carbonate  of  potassium.  It  may  be  crystallized  from 
alcohol  or  by  sublimation. 

Test. — Concentrated  nitric  acid,  or  a mixture  of  chlorate  of  potas- 
sium and  hydrochloric  acid,  rapidly  oxidizes  theia,  forming  com- 
pounds which  with  ammonia  yield  a beautiful  purple-red  color,  re- 
sembling the  murexid  obtained  under  similar  circumstances  from  uric 
acid ; the  oxidation  must  not  be  carried  too  far.  Theine  boiled  with 
caustic  potash  yields  methylamine*(CH3HHN),  the  vapor  of  which 
has  a peculiar,  characteristic  odor. 

30* 


354 


THE  ALKALOIDS. 


The  chemical  action  of  theia  on  the  system  is  not  yet  made  out. 
Liebig  thinks  it  may  aid  in  the  production  of  a substance  a normal 
amount  of  which  is  so  necessary,  an  abnormal  so  unpleasant — namely, 
bile.  Most  chemists  agree  that  it  arrests  the  rapid  consumption  of 
tissue  and  consequent  feeling  of  fatigue  which  is  especially  experi- 
enced after  hard  work  with  mind  or  body. 

Yeratria,  or  Yeratrine  (C32H5.^N208). — This  alkaloid,  as  gallate 
of  veratria,  is  stated  to  occur  in  various  species  of  Veratrum  (Hel- 
lebore) (as  Veratri  Viridis  Radix,  B.  P.),  in  Cevadilla  {Sahadilla, 
B.  P.),  and  in  Colchicum  autumnale  [Colchici  Cormus  ; Colchici 
Semina,  B.  P.) ; but,  according  to  C.  Bullock,  Veratrum  viride 
contains  an  alkaloid  soluble  in  ether  and  one  insoluble  in  that  men- 
struum, neither  answering  in  chemical  reactions  to  veratria.  White 
Hellebore  is  also  said  to  contain  three  other  alkaloids,  sahadillia  or 
sahadilline,  colchicia  or  colchicine,  andyeri;m  or  jervine.  A mere 
trace  of  veratria  brought  into  contact  with  the  mucous  membrane  of 
the  nose  causes  violent  fits  of  sneezing.  Fuming  sulphuric  acid 
colors  it  yellow,  red,  and  violet  in  succession.  Colchicia  is  colored 
of  a brownish-yellow  by  sulphuric  acid,  and  of  a reddish-blue  turning 
to  greenish-yellow  by  nitric  acid. 

The  official  process  for  the  preparation  of  the  alkaloid  ( Veratria, 
B.  P.)  consists  in  exhausting  the  disintegrated  cevadilla  seeds  by 
alcohol,  recovering  most  of  the  spirit  by  distillation,  pouring  the 
residue  into  w^ater,  by  which  much  resin  is  precipitated,  filtering,  and 
precipitating  the  veratria  from  the  aqueous  solution  by  ammonia.  It 
is  purified  by  washing  with  w^ater,  solution  in  dilute  hydrochloric 
acid,  decolorization  of  the  liquid  by  animal  charcoal,  reprecipitation 
by  ammonia,  w^ashing,  and  drying.  The  U.  S.  P.  process  is  similar, 
but  includes  treatment  of  the  first  crude  veratria  by  diluted  sulphu- 
ric acid  and  precipitation  of  alkaloid  by  magnesia. 

Unguentum  Veratrice,  B.  P.,  contains  eight  grains  of  the  slightly 
impure  alkaloid  obtained  as  just  described,  rubbed  down  with  half  a 
drachm  of  olive  oil  and  diffused  through  one  ounce  of  prepared  lard. 


QUESTIONS  AND  EXERCISES. 

694.  How  is  Aconitia  prepared  ? 

695.  Give  the  strengths  of  the  official  preparations  of  Atropia. 

696.  Describe  the  properties  of  atropia. 

697.  What  is  the  active  principle  of  stramonium  ? 

698.  Mention  pharmacopoeial  substances  containing  beberia  and 
berberia  respectively. 

699.  Give  the  characters  of  beberia. 

700.  In  what  does  nectandria  differ  from  beberia  ? 

701.  Mention  the  characteristics  of  conia. 

702.  What  is  the  active  principle  of  Ipecacuanha  ? 

703.  Name  the  alkaloid  of  Tobacco. 

704.  Give  the  p£i,me  and  properties  of  the  active  principle  of  Cala- 
bar Bean. 


STARCH. 


355 


705.  What  are  the  sources  of  piperia  ? 

706.  Whence  is  theia  obtained  ? 

707.  Describe  the  preparations  of  Yeratria. 

708.  State  the  properties  of  veratria. 


BITTEE  (TONIC)  SUBSTANCES. 

The  following  official  articles,  commonly  employed  medicinally 
in  such  forms  as  Decoction,  Extract,  Infusion,  Tincture,  contain 
active  principles  which  have  not  yet  been  thoroughly  examined. 
Some  of  these  principles  have  been  isolated,  and  a few  have  been 
obtained  in  the  crystalline  condition  ; but  their  constitution  has  not 
been  sufficiently  well  made  out  to  admit  of  the  classification  of  the 
bodies  either  among  alkaloids,  glucosides,  acids,  or  other  well-marked 
principles. 


Absinthium  (Absinthin). 

Anth  emidis  flares. 

Aurantii  cortex. 

Buchu  folia. 

Canellce  alhce  cortex. 

Cascarillce  cortex. 

Chirata. 

Chimaphila  (Arbutin). 
Cusparice  coHex,  or  Angustura. 
U.  S.  P.,  contains  Cusparin  or 
Angusturin. 


Gentiance  radix. 

Lactuca  (Lactucin). 

Lupidus. 

Maticce  folia. 

Marruhium. 

Quassice  lignum  (Quassin,  C,, 

Serpent  an  ce  radix. 

Spigelia  marilandica. 
Taraxaci  radix  (Taraxacin). 


AMYLACEOUS  AND  SACCHARINE  SUBSTANCES. 

STARCH. 

Formula  CgHj^O,. 

Processes. — Rasp  or  grate,  or,  wuth  a knife,  scrape  a por- 
tion of  a clean  raw  potato,  letting  the  pulp  fall  on  to  a piece 
of  muslin  placed  over  a small  dish  or  test-glass,  and  then 
pour  a slow  stream  of  water  over  the  pulp ; minute  par- 
ticles or  granules  of  starch  pass  through  the  muslin  and 
sink  to  the  bottom  of  the  vessel,  fibrous  matter  remaining 
on  the  seive.  This  is  potato-starch.  Even  diseased  pota- 
toes furnish  good  starch  by  this  method.  Wheat-starch 
{Amyhim^  B.  P.  and  U.  S.  P.)  may  be  obtained  by  tying  up 
some  flour  in  a piece  of  calico  and  kneading  the  bag  in  a 
slow  stream  of  water  flowing  from  a tap,  the  washings  run- 
ning into  a deep  vessel,  at  the  bottom  of  which  the  white 
starch  collects : the  sticky  matter  remaining  in  the  bag  is 


356  AMYLACEOUS  AND  SACCHARINE  SUBSTANCES. 

gluten.  Tli^  blue  starch  of  the  shops  is  artificially  colored 
with  smalt  or  indigo,  to  neutralize  the  yellow  tint  of  recently 
washed  linen  ; it  should  not  be  used  for  medicinal  purposes. 
Starch  dried  in  mass  splits  up  into  curious  columnar 
masses,  resembling  the  basaltic  pillars  of  Fingal’s  Cave  in 
Staffa,  or  those  of  the  Giant ^s  Causeway  in  the  North  of 
Ireland.  The  cause  of  the  phenomenon,  which  may  also 
be  seen  in  grain-tin,  is  not  conclusively  known. 

Gluten  is  the  body  which  gives  tenacity  to  dough  and  bread.  It 
seems  to  be  a mixture  of  vegetable  fibrin,  vegetable  casein,  and  an 
albuminous  matter  termed  glutin.  These  substances  and  gluten  itself 
are  closely  allied;  each  contains  about  16  per  cent,  of  nitrogen. 
Wheaten  Flour  [Farina  Tritici,  B.  P.)  contains  about  72  per  cent, 
of  starch  and  11  of  gluten,  as  well  as  sugar,  gum,  fine  bran,  water, 
and  ash.  The  compactness  of  barley,  well  seen  in  Husked  or  Pearl 
Barley  [Hordeum  Decorticatum,  B.  P.  and  U.  S.  P ),  is  said  to  be 
due  to  the  large  amount  of  vegetable  fibrin  present.  During  ger- 
mination the  fibrin  is  destroyed,  hence,  probably,  the  cretaceous 
character  of  malt.  Oatmeal  [Avence  Farina,  U.  S.  P.)  is  very  rich 
in  albuminoid  or  flesh-forming  constituents,  containing  nearly  16  per 
cent.  Sago,  U.  S.  P.,  is  granulated  starch  from  the  Sago  Palm. 
Tapioca,  D.  S.  P.,  is  granulated  starch  from  the  Bitter  Cassava. 

Mucilage  of  Starch. — Mix  two  or  three  grains  of  starch 
with  first  a little  and  then  more  water,  and  heat  to  the 
boiling-point;  mucilage  of  starch  {Mucilago  Amyli.^  B.  P.) 
results. 

This  mucilage  or  paste  is  not  a true  solution ; by  long  boiling, 
however,  a portion  of  the  starch  becomes  dissolved.  In  the  latter 
case  the  starch  probably  becomes  somewhat  altered. 

Chemical  Test. — To  some  of  the  mucilage  add  a little 
free  iodine ; a deep-blue  color  is  produced. 

This  reaction  is  a very  delicate  test  of  the  presence  of  either 
iodine  or  starch.  The  starch  must  be  in  the  state  of  mucilage  ; 
hence  in  testing  for  starch  the  substance  supposed  to  contain  it  must 
be  first  boiled  in  water.  The  solutions  used  in  the  reactions  should 
also  be  cold,  or  nearly  so,  as  the  blue  color  disappears  on  heating, 
though  it  is  partially  restored  on  cooling.  The  iodine  reagent  may 
be  iodine-water  or  tincture  of  iodine.  In  testing  for  iodine  its  occur- 
rence in  the  free  state  must  be  insured  by  the  addition  of  a drop,  or 
even  less,  of  chlorine-water.  Excess  of  chlorine  must  be  avoided,  or 
chloride  of  iodine  will  be  formed,  which  does  not  color  starch. 

3'he  so-called  iodide  of  starch  scarcely  merits  the  name  of  a 
chemical  compound,  the  state  of  union  of  its  constituents  being 
feeble.  Substances  that  attack  free  iodine  remove  that  element  from 
iodide  of  starch.  The  alkalies,  hydrosulphuric  acid,  sulphurous  acid, 
and  other  reducing  agents  destroy  the  blue  color. 

Microscopical  Test, — All  kinds  of  starch  yield  the  blue  color 


DEXTRIN. 


35t 


with  iodine,  showing  their  chemical  similarity.  But  physically  the 
granules  of  starch  from  different  sources  differ  much  in  size  and 
appearance  when  examined  by  the  microscope  with  or  without  the 
aid  of  polarized  light.  The  granules  of  potato-starch  are  large,  of 
rice-starch  very  small,  arrowroot  [Maranta,  U.  S.  P.),  and  wheat- 
starch  being  intermediate.  By  polarized  light  the  granules  of  potato- 
starch  appear  as  if  traversed  by  a black  cross,  the  wheat-starch 
granules,  as  seen  in  common  flour,  similarly  influence  polarized  light, 
but  oat-starch  yields  no  such  effect.  (See  the  frontispiece  plates  of 
the  original  edition  of  Pereira’s  “ Materia  Medica.”)  The  granules 
of  Tons  les  Mots  [Canna^  U.  S.  P.)  are  very  large. 

Dextrin. — Mix  a grain  or  two  of  starch  with  about  half 
a test-tubeful  of  cold  water  and  a drop  or  two  of  sulphuric 
acid,  and  boil  the  mixture  for  a few  minutes  ; no  mucilage 
is  formed,  and  the  liquid,  if  sufficiently  boiled,  yields  no 
blue  color  with  iodine  ; the  starch  has  become  converted 
into  dextrin.  The  same  effect  is  produced  if  the  starch  is 
maintained  at  a temperature  of  about  320°  F.  for  a short 
time.  Dextrin  is  now  largely  manufactured  in  this  way, 
and  a paste  of  it  used  by  calico-printers  as  a vehicle  for 
colors  ; it  is  termed  British  gum.  The  change  ma}^  also 
be  effected  by  diastase.,  a peculiar  ferment  existing  in  malt. 
Mix  two  equal  quantities  of  starch  with  equal  amounts  of 
water,  adding  to  one  a little  ground  malt,  then  heat  both 
slowly  to  the  boiling-point ; the  mixture  without  malt 
thickens  to  a paste  or  pudding,  that  with  malt  remains 
thin,  its  starch  having  become  converted  into  dextrin. 

Diastase  is  probably  the  vegetable  fibrin  of  gluten  in  a state  of 
decomposition  ; it  is  so  named  from  [diastasis),  separation, 

in  allusion  to  the  separation,  or  rather  alteration,  it  effects  among 
the  constituent  atoms  of  starch. 

Malt  (the  word  malt  is  said  to  be  derived  from  the  Welsh  mall,  soft 
or  “rotten”)  is  simply  barley  which  has  been  softened  by  steeping  in 
water,  allowed  to  germinate  slightly,  and  further  change  then  arrested 
by  the  application  of  heat  in  a kiln.  During  germination  the  gluten 
breaks  up  and  yields  a glutinous  substance  termed  vegetable  gela- 
tine, diastase,  and  other  matters.  To  the  vegetable  gelatine  is  due 
much  of  the  “ body”  of  well-malted  and  slightly-hopped  beer ; it  is 
precipitated  by  tannic  acid,  hence  the  thinness  of  ale  (pale  or  bitter) 
brewed  with  a large  proportion  of  hop  or  other  materials  containing 
tannic  acid.  A portion  of  the  diastase  reacting  on  the  starch  of  the 
barley  converts  it  into  dextrin,  and,  indeed,  carries  conversion  to  the 
further  si  age  of  grape-sugar,  as  will  be  explained  immediately.  The 
temperature  to  which  the  malt  is  heated  is  made  to  vary,  so  that  the 
sugar  of  the  malt  may  or  may  not  be  partially  altered  to  a dark- 
brown  coloring  material ; if  great,  the  malt  is  said  to  be  high-dried, 
and  is  used  in  porter-brewing;  if  low,  the  product  is  of  lighter  color, 
and  is  used  for  ale.  The  diastase  remaining  in  malt  is  still  capable 


358  AMYLACEOUS  AND  SACCHARINE  SUBSTANCES. 


of  converting  a large  quantity  of  starch  into  dextrin  and  sugar ; hence 
the  makers  op  distillers  of  the  various  spirits  operate  on  a mixture  of 
malted  and  unmalted  grain  in  preparing  liquors  for  fermentation. 

Gum  is  a frequent  constituent  of  vegetable  juices,  existing  in  large 
quantity  in  several  species  of  acacia.  According  to  Fremy  gum  is 
a calcium  salt,  sometimes  partially  a potassium  salt  of  the  gummic 
or  arahic  radical.  The  formula  of  gummic  acid  is  said  to  be  H2C,2 
G um  differs  from  dextrin  in  yielding  oxalic  acid  but 
no  mucic  acid  when  oxidized  by  nitric  acid.  Cerasm  or  cherry-tree 
gum  is  an  insoluble  modification  of  acacia  gum.  (C,2H2oOjo) 

is  a form  of  gum  which  is  insoluble  in  water,  but  absorbs  a large 
quantity  of  that  liquid  and  forms  a gelatinoid  mass.  It  occurs 
largely  in  Tragacanth,  combined,  like  arabin,  with  calcium.  Pectin 
or  vegetable  jelly  (032H^o028,  4H2O)  is  the  body  which  gives  to  ex- 
pressed vegetable  juices  the  property  of  gelatinizing.  It  forms  the 
chief  portion  of  Irish  or  Carrageen  moss  ( Chondrus  crispus,  U.  S.  P.). 

Isomerism.  Allotropy.  Polymorphism. 

The  composition  of  dextrin  is  represented  by  the  same  formula  as 
that  of  starch,  namely  CgH^pO^;  for  it  has  the  same  percentage  com- 
position as  starch.  Cellulose  (see  next  page)  has  also  a similar  for- 
mula. There  are  many  other  bodies  similar  in  centesimal  composition, 
but  dissimilar  in  properties;  such  substances  are  termed  isomeric 
isos,  equal,  and^utpo^,  meros,  part) ; and  their  condition  is  spoken 
of  as  one  of  isomerism.  There  is  sometimes  good  reason  for  doubling 
or  otherwise  multiplying  the  formula  of  one  of  two  isomeric  bodies. 
Thus  olefiant  gas  (ethylene),  the  chief  illuminating  constituent  of  coal- 
gas,  is  represented  by  the  formula  C2H4,  while  amylene,  an  anaesthetic 
liquid  hydrocarbon,  obtained  from  amylic  alcohol,  though  having  the 
same  percentage  composition  as  olefiant  gas,  is  represented  by  the  for- 
mula for  the  latter,  when  gaseous,  is  about  twice  and  a half 

as  heavy  as  the  former,  and  must  contain,  therefore,  in  equal  volumes, 
twice  and  a half  as  many  atoms  ; its  formula  is,  consequently,  for  this 
and  other  reasons,  constructed  to  represent  those  proportions.  This 
variety  of  isomerism  is  termed  (from  Tto'kvi^.  polus,  many 

or  much,  and  ^uspo^,  part).  Metastannic  acid  [vide  p.  21.5)  is  a poly- 
meric variety  of  stannic  acid.  An  illustration  of  a second  variety  of 
isomerism  is  seen  in  the  case  of  cyanate  of  ammonium  and  urea,  bodies 
already  alluded  to  in  connection  with  cyanic  acid.  These  and  several 
other  pairs  of  chemical  substances  have  dissimilar  properties,  yet 
are  similar  not  only  in  elementary  composition  and  in  the  centesimal  j 
proportion  of  the  elements,  but  also  in  the  fact  that  each  molecule  1 
possesses  the  same  number  of  atoms.  But  the  reactions  of  these 
bodies  indicate  the  probable  nature  of  their  construction ; and  this  is 
shown  in  their  formula  by  the  disposition  of  the  symbols.  Thus 
cyanate  of  ammonium  is  represented  by  the  formula  NII^CNO,  urea  • 
by  C11^N20.  Such  bodies  are  termed  metameric  (from^ttfra,  meta,  a ; 
preposition  denoting  change,  and  /U£poj),  and  their  condition  spoken  I 
of  as  one  of  metamerism.  'J'he  isomerism  of  starch  and  dextrin  1 
may  be  of  a polymeric  or  of  a metameric  character ; but  we  do  not  i 


CELLULTN. 


359 


yet  know  which,  and  must  therefore  at  present  give  them  identical 
formulae.  Substances  similar  in  composition  and  constitution,  yet 
differing  in  properties,  are  termed  allotropic  {aXKo^,  alios,  another, 
'T'porto^,  tr  op  os,  condition).  Thus  ordinary  phosphorus,  kept  at  a tem- 
perature of  about  450^  Fahr.,  in  an  atmosphere  from  which  air  is 
excluded,  becomes  red,  opaque,  insoluble  in  liquids  in  which  ordi- 
nary phosphorus  is  soluble,  oxidizes  extremely  slowly,  and  only 
ignites  when  heated  to  near  500^  Fahr.  (red  or  amorphous  phospho- 
rus). Other  allotropic  varieties  of  phosphorus  are  known.  Another 
illustration  of  allotropy  is  seen  in  the  varieties  of  tartaric  acid,  which 
have  different  optical  properties,  but  otherwise  are  identical ; they 
are  in  neither  of  the  above-mentioned  states  of  isomerism,  but  are 
allotropic  modifications  of  the  same  substance.  Occasionally  one  and 
the  same  substance  crystallizes  in  two  distinct  forms,  its  state  is  then 
described  as  one  oi polymorphism  [Tto’kv^.polus,  many,  morplie, 
form).  Sulphur  is  polymorphous.  It  crystallizes  by  slow  cooling  in 
(1)  prismatic  crystals  of  sp.  gr.  1.98,  while  in  nature  it  occurs  in  (2) 
octahedra  of  sp.  gr.  2.07.  Melted  and  poured  into  water,  sulphur 
takes  up  the  form  of  (3)  caoutchouc  of  sp.  gr.  1.96.  These  differences 
warrant  the  statement  that  sulphur  occurs  in  three  distinct  allotropic 
conditions. 

Cellulin  or  cellulose,  the  woody  fibre  of  plants,  familiar  in  the 
nearly  pure  state,  under  the  forms  of  “ cotton-wool”  ( Gossypium, 
B.  P.  and  U.  S.  P.,  “ hairs  of  the  seed  of  various  species  of  Gossy- 
pium”), paper,  linen,  and  pith,  is  another  substance  isomeric,  probably 
polymeric,  with  starch.  Lignin  is  a closely  allied  body,  lining  the 
interior  of  woody  cells  and  vessels.  By  the  action  of  nitric  acid  of 
various  strengths  on  cellulin,  peroxide  of  nitrogen  {NO2)  is  substi- 
tuted for  one,  two,  or  three  atoms  of  hydrogen — mono-,  di-,  or  tri- 
nitrocellulin  being  formed : — 


+ 

HNO3  = 

+ ‘*•0 

Cellulin. 

Nitric  acid. 

Mononitrocellulin.  Water. 

CeH.oOs 

+ 

2HNO3  = 

«-{2n6,[o.  + “.o 

Cellulin. 

Nitric  acid. 

Dinitrocellulin.  Water. 

CeH.oO, 

+ 

3HNO3  = 

c.l3Sb,}o>+ 

Cellulin. 

Nitric  acid. 

Trinitrocellulin.  Water. 

Trinitrocellulin  is  highly  explosive  gun-cotton  ; dinitrocellulin  is  not 
sufficiently  explosive  for  use  instead  of  gunpowder ; mononitroceb 
lulin  is  scarcely  at  all  explosive.  1'he  three  movable  atoms  of  hy- 
drogen in  cellulin  may  be  displaced  by  bodies  other  than  peroxide 
of  nitrogen. 

Dinitrocellulin  (Pyroxylin^  B.  P.)  may  be  prepared  by 
the  following  process:  Mix  5 fliiidounces  of  sulphuric  acid 
and  5 of  nitric  in  an  earthenware  mortar,  immerse  1 ounce 
of  cotton  wool  in  the  mixture,  and  stir  it  for  three  minutes 
with  a glass  rod  so  that  it  is  thoroughly  and  uniformly 


360  AMYLACEOUS  AND  SACCHARINE  SUBSTANCES. 

wetted  by  the  acids.  Transfer  the  cotton  to  a vessel  con- 
taining a considerable  voliinie  of  water,  stir  it  rapidly  and 
well  with  a glass  rod,  decant  the  liquid,  pour  more  water 
upon  the  mass,  agitate  again,  and  repeat  the  affusion,  agita- 
tion, and  decantation  until  the  washing  ceases  to  give  a 
precipitate  with  chloride  of  barium.  Drain  the  product  on 
filtering  paper,  and  dry  in  a water-bath. 

The  Pyroxylin,  U.  S.  P.,  is  made  by  macerating  half  a troy  ounce 
of  cotton  for  fifteen  hours  in  a mixture  of  four  troy  ounces  of  sulphu- 
ric acid  and  three  and  a half  troy  ounces  of  nitric,  and  washing  as 

above.  . 

Pyroxylin  may  also  be  made  by  soaking  7 parts  of  white  faltering 
paper,  which  has  been  washed  in  hydrochloric  acid  and  dried,  in  a 
mixture  of  140  parts  of  sulphuric  acid  (sp.  gr.  1.82)  and  70  of  nitric 
acid  (1.37)  for  three  hours,  and  well  washing  the  product  (Guichard). 

MononitTOcellidin  and  trinitrocellulin  are  insoluble  in  a mixture 
of  alcohol  and  ether ; dinitrocelluUn  or  pyroxylin  is  soluble,  the 
solution  forming  ordinary  collodion  [Collodium,  B.  P.  and  U.  S.  P.). 
The  official  proportions  are  1 ounce  of  pyroxylin  dissolved  in  a mix- 
ture of  36  fiuidounces  of  ether  and  12  of  rectified  spirit.  After 
digesting  for  a few  days,  the  liquid  is  decanted  from  any  insoluble 
matter  and  preserved  in  a well-corked  bottle.  It  is  “ a colorless, 
highly  inflammable  liquid  with  ethereal  odor,  which  dries  rapidly 
upon  exposure  to  the  air,  and  leaves  a thin  transparent  film,  insoluble 
in  water  or  rectified  spirit.”  Flexible  collodion  ( Collodium  Flexile, 
B.  P.,  and  U.  S.  P.)  is  a mixture  of  collodion  (6  fiuidounces),  Canada 
Balsam  (120  grains),  and  castor  oil  (1  fluidrachm). 


QUESTIONS  AND  EXERCISES.  ji 

i 

709.  How  is  wheat-starch  or  potato-starch  isolated  ? j 

710.  Define  gluten  and  glutin,  ! 

711.  Enumerate  the  proximate  principles  of  wheaten  flour.  | 

712.  Is  starch  soluble  in  water  ? ! 

713.  Which  is  the  best  chemical  test  for  starch?  j 

714.  Distinguish  ph3^sically  between  the  varieties  of  starch.  j 

715.  Into  what  compound  is  starch  converted  by  heat  ? j 

716.  AVhat  occurs  when  a mixture  of  starch  and  water  is  allowed  | 

to  flow  into  hot  diluted  sulphuric  acid  ? j 

717.  If  equal  amounts  of  starch  and  water  be  heated,  one  contain- 
ing a small  quantity  of  ground  malt,  what  effects  ensue  ? ; 

718.  Write  a short  article  on  the  chemistry  of  “ malting.”  ! 

719.  What  is  the  nature  of  gum  arabic  and  how  is  it  distinguished; 
from  “ British  Gum”  ? 

720.  Explain  isomerism,  as  illustrated  by  starch  and  dextrin. 

721.  Give  examples  of  polymeric  bodies. 

722.  State  the  formula  of  a body  metameric  with  urea. 

723.  Define  allotropy  and  polymorphism,  giving  illustrations.  | 


SUGARS. 


361 


724.  What  form  of  cellulin  is  official  ? 

725.  Mention  the  properties  of  the  products  of  the  action  of  nitric 
acid  of  various  strengths  on  cellulin. 

726.  How  is  pyroxylin  prepared. 


SUGARS. 

Cane-sugar,  Ci,H220ii.  Inverted-sugar, 

Grape-sugar,  CgHi206,H20.  Milk-sugar,  Cj2H220ii,H20. 

Artificial  formation  of  Grape-sugar  from  Cane-sugar. — 
Tests  for  Sugar. — Dissolve  a grain  or  two  of  common 
cane-sugar  in  water.  To  a portion  of  this  solution  placed 
in  a test-tube  add  more  water,  two  or  three  drops  of  solu- 
tion of  sulphate  of  copper,  a considerable  quantity  of  solu- 
tion of  potash  or  soda  (enough  to  turn  the  color  of  the 
liquid  from  a light  to  a dark-blue),  and  heat  the  mixture  to 
the  boiling-point;  no  obvious  change  occurs.  To  another 
portion  of  the  syrup  add  a drop  of  sulphuric  acid,  and  boil 
for  ten  or  twenty  minutes,  then  add  the  copper  solution 
and  alkali,  and  heat  as  before  ; a yellowish-red  precipitate 
of  cuprous  oxide  (CU2O)  falls.  This  test  is  exceedingly 
delicate. 

The  above  reaction  is  due  to  the  conversion  of  the  cane-sugar 
(C12H22O1J)  into  inverted-sugar,  or  Icevulose,  CgHi20g  (so-called  be- 
cause its  solution  causes  left-handed  rotation  of  a ray  of  polarized 
light,  cane-sugar  having  an  opposite  effect),  and  grape-sugar  0gHi20g, 
H2O,  by  the  influence  of  the  sulphuric  acid,  and  to  the  reducing 
action  of  the  inverted-sugar  and  the  grape-sugar  on  the  cupric  solu- 
tion. The  formation  of  a precipitate  immediately,  without  the 
action  of  acid,  shows  the  presence  of  the  latter  sugars — its  formation 
only  after  ebullition  with  acid  indicating,  in  the  absence  of  starch 
or  dextrin,  cane-sugar.  In  this  reduction  process  the  sugar  is  oxi- 
dized and  broken  up  into  several  substances  ; the  exact  nature  of  the 
reaction  has  not  been  ascertained. 

Cane-sugar  or  sucrose  [Saccharum  Furificatum,  B.  P.  and  U.  S. 
P.)  is  a frequent  constituent  of  vegetable  juices.  Thus  it  forms  the 
chief  portion  of  cassia-pulp  [Cassice  Pulpa,  B.  P.),  is  contained  in 
the  carrot  and  turnip,  but  is  most  plentiful  in  the  sugar-cane ; much, 
however,  is  now  obtained  from  the  sugar-maple  and  beetroot.  On 
the  evaporation  of  the  juice,  common  brown  or  moist  sugar  crystal- 
lizes out ; this,  by  resolution,  filtration  through  animal  charcoal, 
evaporation  to  a strong  syrup,  and  crystallization  in  moulds,  yields  the 
compact  crystalline  conical  loaves  known  in  trade  as  lump-sugar. 
From  a slightly  less  strong  syrup,  slowly  cooled,  the  crystals  termed 
sugar-candy  are  deposited,  white  or  colored  according  to  the  color 
of  the  syrup. 

31 


362  AMYLACEOUS  AND  SACCHARINE  SUBSTANCES. 


Inverted  Suyar  or  Lcevidose  is  uncrystallizable.  It  is  found  in 
the  grape,  fig  [Ficus,  B.  P.  and  U.  S.  P.),  cherry,  and  gooseberry; 
both  grape-sugar  and  inverted  sugar  in  the  strawberry,  peach, 
plum,  etc. 

Grape-sugar  or  glucose  (from  ykvxv<;,  glucus,  sweet)  is  often  seen 
in  the  crystallized  state,  in  dried  grapes  or  raisins  and  other  fruits ; 
it  is  also  the  variety  of  sugar  met  with  in  diabetic  urine.  Its  crys- 
talline character  is  quite  distinct  from  that  of  cane-sugar,  the  latter 
forming  large  four  or  six-sided  rhomboidal  prisms,  while  grape-sugar 
occurs  in  masses  of  small  cubes  or  square  plates.  Grape-sugar  is 
also  less  soluble  in  water  but  more  soluble  in  alcohol  than  cane-sugar. 

Laevulose  is  laBvogyrate,  while  Sucrose  and  Glucose  possess  right- 
handed  rotation  ; the  latter  twist  a ray  of  polarized  light  from  left 
to  right,  to  an  extent  dependent  on  the  amount  of  sugar  present — a 
fact  easy  of  application  in  estimating  the  amount  of  sugar  in  syrups 
or  in  diabetic  urine. 

Both  cane-sugar  and  grape-sugar  yield  alcohol  and  carbonic  acid 
gas  by  fermentation,  the  cane-sugar  probably  always  passing  into 
grape-sugar  before  the  production  of  alcohol  commences. 

= 2C,H,HO  + 2CO, 

^ Grape-sugar,  Alcohol.  Carbonic 

acid  gas. 

In  bread-making,  some  of  the  starch  is  converted  into  dextrin, 
and  this  into  sugar  by  the  ferment.  The  above  action  then  goes  oq, 
the  liberation  of  gas  producing  the  rising  or  swelling  of  the  mixture 
of  flour,  water,  and  yeast  (dough) — the  temperature  to  which  the 
mass  is  subjected  in  the  oven  causing  escape  of  alcohol,  and  further 
expansion  of  the  bubbles  of  carbonic  acid  gas  in  every  part  of  the 
now  spongy  loaf.  The  carbonic  acid  gas  gradually  evolved  when 
flour  is  worked  up  for  bread  with  a mixture  of  dry  bicarbonate  of 
sodium  and  tartaric  acid  (best  preserved  by  previous  admixture  with 
dried  flour  and  a little  carbonate  of  magnesium) — haking-poivder — 
exerts  similar  influence.  The  least  objectionable  method  of  intro-  f 
ducing  carbonic  acid  gas,  however,  is  that  of  Dauglish,  whose  patent 
Aerated  Bread  is  made  from  flour  by  mere  admixture  with  carbonic- 
acid  water  under  pressure.  On  removal  from  the  cylinder,  the  result- 
ing dough  expands  by  the  natural  elasticity  of  the  imprisoned  car- 
bonic acid,  and  the  bake-oven  completes  the  process.  The  crumb  of 
bread  is  official  [Mica  Fanis,  B.  P.). 

Milk-sugar  or  lactose  (Gi.,H2^0i2)  (Saccharum  Lactis,  B.  P.  and 
U.  S.  P),  the  sweet  principle  of  the  milk  of  various  animals,  is  not 
susceptible  of  alcoholic  or  vinous  fermentation;  but  it  resembles  j 
grape-sugar  in  reducing  an  alkaline  solution  of  copper  with  precipi-  | 
tation  of  suboxide.  It  is  readily  obtained  from  milk  by  adding  a • 
few  drops  of  acid,  stirring,  setting  aside  for  the  curds  to  separate,  j 
filtering,  evaporating  the  ivliey  to  a small  bulk,  filtering  again  if  , 
necessary,  and  allowing  to  cool  and  crystallize.  It  usually  occurs  in  i 
trade  “ in  cylindrical  masses,  two  inches  in  diameter,  with  a cord  or  : 
stick  in  the  axis,  or  in  fragments  of  cakes — grayish-white,  crystalline  i 
on  the  surface  and  in  its  texture,  translucent,  hard,  scentless,  faintly  | 
sweet,  gritty  when  chewed.”  It  is  soluble  in  6 parts  of  cold  and  3 • 


VARIETIES  OF  SUGAR. 


363 


of  boiling  water ; slightly  soluble  in  alcohol ; insoluble  in  ether. 
Powdered  milk-sugar  is  used  in  pharmacy  as  a vehicle  for  potent 
solid  medicines. 

Action  of  Alkali  on  Sugar. — To  a little  solution  of  grape- 
sugar  add  solution  of  potash  or  soda,  or  solution  of  car- 
bonate of  potassium,  and  warm  the  mixture;  the  liquid  is 
darkened  in  color  from  amber  to  brown,  according  to  the 
amount  of  sugar  present. 

Tests. — The  copper-reaction,  the  fermentation  process,  and  the 
effect  of  alkalies  form  three  good  tests  of  the  presence  of  grape- 
sugar,  and,  indirectly,  of  cane-sugar.  A piece  of  merino  or  other 
woollen  material,  previously  dipped  in  a solution  of  stannic  chloride 
and  dried,  becomes  of  a brown  or  black  color  when  dipped  in  a solu- 
tion of  glucose  and  heated  to  about  300^  F.  by  holding  before  a fire. 

Sugar  from  Starch. — Boil  the  starch  with  a little  water 
and  a drop  of  sulphuric  acid  as  for  dextrin,  but  continue 
the  ebullition  for  several  minutes  ; on  testing  a portion  of 
the  cooled  liquid  with  iodine  and  another  portion  with  the 
heated  alkaline  solution  of  a copper  salt  as  described  on 
page  361,  it  will  be  found  that  the  starch  has  nearly  all 
become  converted  into  grape-sugar,  or  starch-sugar  as  it  is 
sometimes  termed.  When  made  on  a large  scale,  a warm 
(131  ° F.)  mixture  of  starch  and  water  of  the  consistence  of 
cream  is  slowly  poured  into  a boiling  solution  of  one  part 
of  sulphuric  acid  in  one  hundred  of  water,  the  whole  boiled 
for  some  time,  the  acid  neutralized  by  chalk,  the  mixture 
filtered,  the  liquid  evaporated  to  a thick  S3U’up  and  set  aside  ; 
in  a few  da3^s  it  crystallizes  to  a granular  mass  resembling 
honey.  In  this  operation  a small  quantity  of  dextrin  re- 
mains with  the  glucose;  but  if  the  process  be  conducted 
under  pressure,  conversion,  according  to  Manbre,  is  com- 
plete. 

The  sugar  in  fresh  fruits  is  mainly  cane-sugar  ; but  by  the  action 
of  the  acid,  or  possibly  of  a ferment  in  the  juice,  it  is  gradually  con- 
verted into  inverted  sugar,  a variety  differing  from  cane-sugar  in 
being  uncrystallizable,  and  in  having  an  inverted  or  opposite  influ- 
ence on  polarized  light,  twisting  the  ray  from  right  to  left  (laevogy- 
rate,  having  laevo-rotation — hence  sometimes  termed  levulose).  Ripe 
Hips  [Rosce  Canince  Fructus,  B.  P.)  contain  30  per  cent,  of  such 
sugar.  Fruit-sugar,  as  gathered  in  the  form  of  syrup  by  bees,  is 
probably  a mixture  of  these  two  varieties.  It  is  gradually  altered 
to  a crystalline  or  granular  mass  of  grape-sugar,  as  seen  in  dried 
fruits,  such  as  Raisins  {Uvce,  B.  P.,  Uva  Fassa,  tl.  S.  P.),  and  the 
Prune  (Prunum,  B.  P,  and  U.  S.  P.)  and  in  solidified  honey  [Mel, 
B.  P.  and  U.  S.  P.).  This,  the  common  form  of  grape-sugar,  is  dex- 
trogyrate, and  hence  is  sometimes  termed  dextrose,  to  distinguish  it 


364  AMYLACEOUS  AND  S A C 0 H A R I N E S U B S T A N C E S . 


from  levulose.  Honey  often  contains  flocculent  matters  which  cause 
it  to  ferment  and  yield  mannite  (Stoddart),  alcohol,  and  acetic  acid; 
hence  for  use  in  medicine  it  is  directed  [Mel  Depuratum,  B.  P.  and 
U.  S.  P.)  to  be  clarified  by  melting  and  straining,  while  hot,  through 
flannel  previously  moistened  with  warm  water.  A mixture  of  clari- 
fied honey  80  per  cent.,  acetic  acid  10  per  cent.,  and  water  10  per 
cent,  is  official  under  the  name  of  Oxymel  (from  oxus,  acid,  and 
meli,  honey).  A similar  mixture  of  honey  with  acetic  acid 
containing  the  soluble  portions  of  squill-bulbs  (Scilla,  B.  P.  and 
U.  S.  P.)  is  known  as  Oxymel  of  Squill  [Oxymel  Scilicet  B.  P.). 
Honey  or  sugar-cane  are  the  bases  of  the  official  Confections. 

“ Honey  Dew^'  is  a viscid  saccharine  matter  occasionally  met  with 
on  the  leaves  of  the  lime,  maple,  black  alder,  rose,  and  other  trees. 
Sometimes  it  is  sufficiently  abundant  to  dry  and  fall  on  the  ground, 
forming  a veritable  “ shower  of  manna.”  It  is  a mixture  of  cane- 
sugar,  inverted  sugar,  and  dextrin. 

Barley  sugar  is  made  by  simply  heating  cane-sugar  till  it  fuses, 
a change  from  the  crystalline  to  the  uncrystallizable  condition  occur- 
ring. T reach  ( Theriaca,  B.  P.),  Molasses,  [Syrupus  Fuscus,  U.  S. 
P.),  or  Melasses  (from  Mel,  honey),  chiefly  results  from  the  applica- 
tion of  too  much  heat  in  evaporating  the  syrups  of  the  sugar  cane ; 
it  is  a mixture  of  cane-sugar  with  uncrystallizable  sugar  and  color- 
ing-matter. Liquorice-root  [Glycyrrhizce  Radix,  B.  P.)  contains  a 
considerable  quantity  of  uncrystallizable  sugar  [Glycyrrhizin). 

Caramel. — Carefully  heat  a grain  or  two  of  sugar  in  a 
test-tube  until  it  blackens  ; the  product  is  car'amel  or  burnt 
sugar  (the  Saccharum  Ustum  of  pharmacy X.  It  is  used  as 
a coloring  agent  for  gravies,  confectioneries,  spirits,  and 
similar  materials. 

Mannite  (CgHj^Og). — Boil  manna  with  alcohol,  filter,  and 
set  aside ; mannite  separates  in  colorless  shining  crystals 
or  acicular  masses,  to  the  extent  of  from  60  to  80  per  cent, 
of  the  manna. 


Manna,  B.  P.  and  U.  S.  P.,  is  “ a concrete  saccharine  exudation 
from  the  stem  of  Fraxinus  Ornus  and  F.  rotundifolia  ; it  is  ob- 
tained by  making  incisions  in  the  stem  of  the  trees.”  It  occurs  in 
“ stalactiform  pieces  from  one  to  six  inches  in  length,  and  one  or  two 
inches  in  width,  uneven,  porous,  and  friable,  curved  on  one  side,  of 
a yellowish-white  color,  with  a faintly  nauseous  odor,  and  a sweetish 
taste.”  It  is  also  met  with  in  celery,  onions,  asparagus,  certain 
fungi  and  sea-weeds,  occurs  in  the  exudations  of  apple  and  pear 
trees,  and  is  produced  during  the  viscous  fermentation  of  sugar. 

Mannite  is  an  alcohol,  the  radical  of  which  is  sexivalent  (CeUs)’'* 
6110  (Wanklyn).  It  is  closely  related  to  the  sugars,  glucose  becom- 
ing mannite  by  action  of  nascent  hydrogen  : — 


Glucose. 


-I-  n,  = 

Hydrogen. 


CbH„0, 


Maunite. 


Indeed,  glucose  itself  is  probably  an  alcohol  of  another  radical  | 

I 


THE  G LUCOSIDES. 


365 


(C6Hg)'''6HO.  Mannite  does  not  undergo  vinous  fermentation  in 
contact  with  yeast.  It  is  soluble  in  5 times  its  weight  of  cold 
water. 

Mticic  Acid  (H2C6HgOg)  and  Saccharic  Acid  (H2CgHgOg)  are 
two  isomeric  bodies  formed  by  the  action  of  dilute  nitric  acid  on  gum, 
sugar,  and  mannite. 


QUESTIONS  AND  EXEKOISES. 

727.  How  are  cane-sugar  and  grape-sugar  analytically  distin- 
guished ? 

728.  Describe  the  methods  of  extracting  and  purifying  cane-sugar. 

729.  Mention  the  chief  sources  of  cane-sugar. 

730.  Give  chemical  explanations  of  the  different  processes  of 
bread-making. 

731.  How  is  milk-sugar  obtained,  and  in  what  respects  does  it 
differ  from  other  sugar  ? 

732.  By  what  process  may  starch  be  entirely  converted  into 
sugar  ? 

733.  What  is  the  difference  between  fruit-sugar  and  honey  ? 

734.  What  is  Oxymel  ? 

735.  Describe  the  effect  of  heat  on  cane-sugar. 

736.  Describe  the  source  and  character  of  manna. 

737.  Give  the  latest  view  of  the  constitution  of  mannite. 

738.  Whence  are  mucic  and  saccharic  acids  obtained  ? 


THE  GLUCOSIDES. 

Source. — The  Glucosides  are  certain  proximate  vegetable  princi- 
ples which,  by  ebullition  with  dilute  acid,  or  other  method  of  decom- 
position, take  up  the  elements  of  water  and  yield  glucose,  accompa- 
nied by  a second  substance,  which  differs  in  each  case  according  to 
the  body  operated  on.  Twelve  of  the  glucosides  are  of  pharmaceu- 
tical interest,  namely : Amygdalin,  Cathartic  acid,  Colocynthin, 
Convolvulin,  Digitalin,  Elaterin,  Guaiacin,  Jalapin,  Salicin,  San- 
tonin, Scammonin.  Tannin,  or  tannic  acid,  is  also  a glucoside;  it 
has  been  described  among  the  acids. 

^ Note  on  Nomenclature. — The  first  syllable  of  the  names  of  gluco- 
sides and  neutral  principles  generally  are  commonly  given  in  allusion 
to  origin ; the  last  syllable  is  m,  which  sufficiently  distinguishes 
them  as  a class. 

Amygdalin  (CyoH^^NO,^,  3H2O). — This  is  a white  crystal- 
line substance,  existing  in  the  bitter  {Amygdala  Amara^ 
B.  P.  and  U.  S.  P.),  but  not  in  the  sweet  almond  {Amygdala 
Dulcis^  B.  P.  and  U.  S.  P.).  It  is  readil}^  extracted  by  alco- 
hol from  the  cake  left  when  the  fixed  oil  has  been  expressed 

31* 


366  AMYLACEOUS  AND  SACCHARINE  SUBSTANCES. 


from  bitter  almonds.  From  the  concentrated  alcoholic  so- 
lution ether  precipitates  the  amygdalin. 

Make  an  emulsion  of  two  or  three  sweet  almonds  by 
bruising  and  rubbing  them  with  water,  and  notice  that  it 
has  no  odor  of  essential  oil  of  bitter  almonds ; add  a grain 
or  two  of  amj^gdalin,  an  odor  of  essential  oil  of  bitter  al- 
monds is  at  once  developed.  Bruise  two  or  three  bitter 
almonds  and  rub  with  water ; the  volatile  oil  is  again  de- 
veloped {Oleum  Amy gdalse  Amur se^  U.  S.  P.). 

Bitter  Almond-water  {Aqua  Amygdalae  Amarse^  U.  S.  P.) 
is  made  by  filtering  a mixture  of  16  minims  of  the  oil  with 
60  grains  of  carbonate  of  magnesium  and  2 wine-pints  of 
distilled  water. 

The  source  of  the  hydride  of  benzoyl,  or  essential  oil  of  bitter  al- 
monds, in  these  reactions  is  the  amygdalin,  which,  under  the  influ- 
ence of  synaptase  or  emulsin,  a ferment  existing  in  both  bitter  and 
sweet  almonds,  splits  up  into  the  essential  oil,  hydrocyanic  acid,  and 
glucose : — 

-h  = C,H,OH  + HCN  + 

Amygdalin.  Water.  Hydride  of  Hydrocy-  Glucose. 

benzoyl.  auic  acid. 

As  each  molecule  of  amygdalin  yields  one  of  hydrocyanic  acid,  a 
simple  calculation  shows  that  17  grains  (mixed  with  emulsion  of 
sweet  almonds)  will  be  required  to  form  one  grain  of  real  hydro- 
cyanic acid,  a quantity  equivalent  to  50  minims  of  the  dilute  hydro- 
cyanic acid  of  the  British  Pharmacopoeia. 

Test. — The  reaction  between  synaptase  and  amygdalin  is  applica- 
ble as  a test  of  the  presence  of  one  by  the  addition  of  the  other,  even 
when  mixed  with  much  organic  matter. 

Cherry-Laurel-water  (Aqua  Laicrocerasi,  B.  P.,  by  distillation 
with  water  from  Laurocerasi  Folia,  B.  P.)  contains  hydrocyanic 
acid  derived  from  a reaction  similar  to,  if  not  identical  with,  that 
just  described.  But  the  proportion  of  amygadalin  or  analogous  body 
in  cherry-laurel-leaves  is  most  variable;  hence  the  strength  of  the 
water  is  highly  uncertain.  The  preparation  is  worse  than  useless. 

Caution. — Essential  oil  of  almonds  is  highly  poisonous.  The 
purified  oil  or  hydrate  of  benzoyl  is  almost  innocuous ; it  is  obtained 
on  distilling  the  crude  oil  with  milk  of  lime  and  ferrous  chloride. 
Artificial  oil  of  bitter  almonds  or  nitrobenzol  (CgH5(N02))  when 
taken  in  quantity  has  been  known  to  produce  death.  The  presence 
of  nitrobenzol  in  oil  of  bitter  almonds  is  detected  by  adding  a little 
of  the  oil  to  a mixture  of  zinc  and  diluted  sulphuric  acid,  shaking 
well,  setting  aside  for  an  hour  or  two,  filtering  off  the  clear  liquid 
and  adding  a little  chlorate  of  potassium;  a violet  color  (actual 
mauve)  is  produced. 

Arbutin  (OioHjgO,)  is  contained  in  the  leaves  of  Arctostayliylos  | 
uva  ursi  and  Chimaphila  umhellata.  | 

Cathartic  Acid. — “ The  glucoside  acid  that  now  is  known  to  I 
confer  on  the  Senna  of  Alexandria  (Seima  Alexandidana,  B.  P.),  I 


THE  GLUCOSIDES. 


367 


Tinnevely  [Senna  Indica,  B.  P.,  Senna,  U.  S.  P.),  and  probably 
on  American  Senna  [Cassia  Marilandica,  U.  S.  P.),  its  purgative 
property,  has  been  named  by  its  discoverers  (Dragendorf  and  Kubly) 
Cathartic  acid.  Its  formula  has  been  stated  as  Oj8oHj92N4SOg2, 
which,  if  true,  accounts  for  its  extreme  stability.  It  is  insoluble  in 
water,  strong  alcohol,  and  ether,  but  enters  readily  into  watery  solu- 
tion when  combined  with  alkaline  and  earthy  bases,  in  which  state 
it  exists  in  senna.  Its  ammonium  salts  give  brownish  flocculent  pre- 
cipitates with  salts  of  silver,  tin,  mercury,  copper,  and  lead.  Anti- 
monial  salts,  tannin,  yellow  and  red  prussiates  have  no  effect  upon 
it.  Alkalies,  aided  by  heat,  act  destructively  upon  it.  Boiled  with 
a mineral  acid  it  splits  into  a peculiar  kind  of  glucose  and  an  acid 
that  has  been  named  Cathartogenic ; its  formula  is  said  to  be 
Ci32Hh6^4S^44*  ^he  uatural  cathartate  occurring  in  senna  is  pre- 
pared by  partially  precipitating  by  strong  spirit  a water  infusion  of 
senna,  concentrated  to  a syrupy  state  by  evaporation  in  vacuo.  The 
filtrate  is  now  treated  with  a much  larger  bulk  of  absolute  alcohol, 
and  the  precipitate  thus  obtained  is  purified  by  repeated  solution  in 
water  and  precipitation  by  alcohol.  To  obtain  the  pure  acid,  ad- 
vantage is  taken  of  its  colloidal  properties ; the  crude  cathartate  is 
dissolved  in  moderately  strong  hydrochloric  acid,  and  subjected  to 
dialysis  on  a diaphragm  of  parchment  paper.  The  minimum  dose 
of  this  pure  acid  was  found  to  be  about  1^  grain,  which  caused 
several  stools  with  decided  griping. 

“ The  carthartic  combinations  that  I have  made  are,  the  cathar- 
tate of  ammonium,  prepared  from  cathartate  of  lead  by  my  original 
process,  and  the  mixed  cathartates,  prepared  according  to  Dragen- 
dorf’s  method  as  modified  by  myself.  Of  the  former  nearly  pure  salt, 
I have  found  3J  grains  to  purge  fairly  as  to  amount,  but  slowly  as  to 
time,  and  with  considerable  griping.  Of  the  latter  grains  purged 
violently  with  much  griping  and  sickness,  which  continued  through 
the  greater  part  of  the  day.  It  obviously  would  be  improper  to 
combine  senna  with  any  of  its  metallic  precipitants,  should  such  be 
desired,  which  is  not  likely.  It  is  here  satisfactory  to  observe  that 
the  cathartate  of  magnesium  is  soluble,  and  that  the  old-fashioned 
black  draught  agrees  with  new-fashioned  science.”  (Groves.) 

Buckthorn  juice  [Rhamni  Succus,  B.  P.)  owes  its  cathartic  pro- 
perties to  a substance  apparently  identical  with  cathartic  acid. 

Chtratin. — The  active  principle  of  Chiretta  ( Chirata,  B.  P.  and 
U.  S.  P.)  is  said  by  Fluckiger  and  Hohn  to  be  due  to  chiratin,  a 
pale-yellow  neutral  substance  allied  to  the  glucosides. 

CoLOCYNTiiiN  (C5gH84023?). — Tliis  substance  is  the  active  bitter 
and  purgative  principle  of  colocynth-fruit  [Colocynthidis  Ptdpa, 
B.  P.,  Colocyntkis,  U.  S.  P.) : it  is  soluble  in  water  and  alcohol,  but 
not  in  ether.  By  ebullition  with  acids  it  furnishes  glucose  and  a 
resinoid  body. 

OoNvoLvuLiN. — See  Jalapin. 

Digitalin  (C27H45OJJ. — This  is  an  active  principle  of  the 
Foxglove  [Digitalis.^  B.  P.).  Boil  a grain  of  digitalin 
{Digitalimim^  B.  P.  and  U.  S.  P.)  with  sulphuric  acid  for 


368  AMYLACEOUS  AND  SACCHARINE  SUBSTANCES. 

some  time ; flocks  of  digitaliretin  separate,  and 

glucose  may  be  detected  in  the  liquid. 

+ 2H,0  = + 2C,H„0, 

Digitalin.  Water.  Digitaliretin.  Glucose. 

Properties. — Digitalin  occurs  “ in  porous  mammillated  masses  or 
small  scales,  white,  inodorous,  and  intensely  bitter,  readily  soluble 
in  spirit,  but  almost  insoluble  in  water  and  in  pure  ether,  dissolves 
in  acids,  but  does  not  form  with  them  neutral  compounds ; its  solu- 
tion in  hydrochloric  acid  is  of  a faint  yellow  color,  but  rapidly  be- 
comes green.  It  leaves  no  residue  when  burned  with  free  access  of 
air.  It  powerfully  irritates  the  nostrils,  and  is  an  active  poison.” 

Process. — The  official  process  for  the  preparation  of  digitalin  con- 
sists in  dissolving  the  glucoside  out  of  the  digitalis  leaf  [Digitalis 
Folia,  B.  P.  and  U.  S.  P.)  by  alcohol,  removing  the  alcohol  by  distil- 
lation, dissolving  the  residue  in  water  by  the  help  of  a small  quantity 
of  acetic  acid,  removing  much  of  the  color  from  the  solution  by  ani- 
mal charcoal,  neutralizing  most  of  the  acetic  acid  by  ammonia, 
precipitating  the  digitalin  by  tannic  acid  (with  which  it  forms  an 
insoluble  compound),  washing  the  precipitate,  rubbing  and  heating 
it  with  spirit  and  oxide  of  lead  (which  removes  the  acid  in  the  form 
of  insoluble  tannate  of  lead),  again  decolorizing  by  animal  charcoal, 
evaporating  to  dryness,  washing  out  impurities  still  remaining  by 
ether,  and  drying  the  residual  digitalin.  In  this  form  digitalin  is 
uncrystallizable. 

Pure  Digitalin. — On  treating  commercial  digitalin  with  chloro- 
form only  an  inert  substance  remains  undissolved.  The  solution 
yields  pure  digitalin  on  evaporation ; it  may  be  crystallized  from 
spirit  in  radiating  needles.  (Nativelle.)  The  therapeutic  effect  of 
the  pure  substance  is  identical  with  the  preparations  of  digitalis,  but, 
as  might  be  expected,  more  constant  in  its  action  and  of  course 
intensely  powerful. 

Elatertn  (C2oH2g05). — Boil  elateriiim  (Elaterium^  B.  P. 
and  U.  S.  P.),  the  dried  sediment  from  the  juice  of  the 
squirting  cucumber  fruit  {Echalii  Fractus^  B.  P.),  in  a small 
quantity  of  spirit  of  wine,  and  filter;  fibrous  and  amyla- 
ceous matter  remain  insoluble,  while  elaterin  and  resin  are 
dissolved.  The  filtrate,  concentrated  and  poured  into  a 
warm  solution  of  potash,  yields,  on  cooling,  crystals  of 
elaterin,  resin  being  retained  by  the  alkali.  It  is  purified  l 
by  recrystallization  from  spirit.  Boil  elaterium  in  dilute  j 
sulphuric  acid  for  an  hour  or  two,  filter,  and  test  the  clear  i 
liquid  for  glucose;  a reddish  precipitate  of  cuprous  oxide  j 
falls.  This  reaction  is  readily  obtained  with  elaterium, 
but  not  always  with  elaterin;  hence  probably^  the  latter  is  | 
not  a true  glucoside.  | 

Elaterin  is  the  active  principle  of  the  so-called  elaterium.  Elate-  \ 
rium  occurs  “ in  light  friable  slightly  incurved  cakes,  about  one  line  ! 


THE  GLUCOSIDES. 


369 


( incli)  thick,  greenish-gray,  acrid  and  bitter ; fracture  finely  granu- 
lar.” Good  specimens  of  this  drug  should  yield,  according  to  the 
British  Pharmacopoeia,  not  less  than  20  per  cent,  of  elaterin  by  the 
above  process.  Elaterium  is  sometimes  adulterated  with  chalk  and 
other  substances. 

Guaiacin. — Resin  of  guaiaciim  {Guaiaci  Resina^  B.  P. 
and  U.  S.  P.),  an  exudation  from  the  wood  {Guaiaci  Lig- 
num^ B.  P.  and  IJ.  S.  P.)  of  Guaiacum  officinale^  is  probably 
a mixture  of  several  substances,  among  ^vhich  are  Guaia- 
retinic  acid  (C2nH2604)  (Hlasiwetz)  and  Guaiacin,^  a gluco- 
side.  On  boiling  guaiacum-resin  with  dilute  sulphuric 
acid  for  some  time,  glucose  is  found  in  the  liquid,  a green 
resinous  substance  {guaiaretin)  remaining  insoluble  (Kos- 
niann).  Most  oxidizing  agents,  and  even  atmospheric 
air,  especially  under  the  influence  of  certain  organic  sub- 
stances, produce  a blue,  then  green,  and  finally  a brown 
color,  when  brought  into  contact  with  an  alcoholic  solution 
of  guaiacum-resin. 

These  effects  are  said  to  be  due  to  three  stages  of  oxida- 
tion (Jonas).  They  may  be  observed  on  adding  the  solu- 
tion to  the  inner  surface  of  a paring  of  raw  potato. 

Jalapin  AND  CoNVOLVULiN  (Cg^H^gO^g). — Ac- 

cording to  Keyser  and  Meyer,  jalap-resin  contains  two 
distinct  substances  — convolvulin,  chiefly  obtained  from 
Mexican  male  jalap,  and  jalapin,  most  largel}^  contained 
in  the  true  jalap ; the  former  is  soluble  in  ether,  the  latter 
insoluble.  Boil  jalap-resin  with  dilute  sulphuric  acid  for 
some  time  and  filter ; a substance,  which  is  probably  a 
tnre  of  jalapinol  (€^3112403)  and  convolculinol  (C^gHgoOg), 
separates ; and  glucose  may  be  detected  in  the  clear  liquid. 
(It  is  to  be  regretted  that  the  authors  transpose  the  above 
names,  terming  the  old  well-known  jalapin  convolvulin.) 

C,,H„0,,  + 5H,0  ^ C,3H,,03  + 3C,H.A 

Jalapin.  Water.  Jalapinol.  Glucose. 

Jolapic  Acid, — This  is  contained  in  the  portion  of  jalap- 
resin  soluble  in  ether.  It  may  also  be  obtained  from  jalapin 
by  ebullition  with  alkalies  : — 

2C,„Hs„Oj5  + 3H,0  = 

Jalapin.  Water.  Jalapic  acid. 

Jalap-resin  {Jalapde  Resina^  B.  P.  and  IT.  S.  P.)  is  ob- 
tained by  digesting  and  percolating  jalap  tubercles  {Jalapa^ 
B.  P.  and  U.  S.  P.)  with  spirit  of  wine,  adding  a little 
water,  distilling  off  the  spirit,  pouring  awaj^  the  aqueous 
portion  which  contains  much  saccharine  matter,  and  wash- 


3t0  AMYLACEOUS  AND  SACCHARINE  SUBSTANCES. 


ing  and  drying  the  residual  resin.  The  tincture  is  some- 
times decolorized  by  animal  charcoal,  and  the  evaporated 
product  sold  as  jalapin. 

Jalap-resin  is  insoluble  in  oil  of  turpentine ; common  resin,  or 
rosin,  soluble.  If  the  presence  of  the  latter  is  suspected,  the  speci- 
men should  be  powdered,  digested  in  turpentine,  the  mixture  filtered, 
and  the  filtrate  evaporated ; no  residue,  or  not  more  than  yielded  by 
the  turpentine  itself,  should  be  obtained. 

Saltcin  (CigHjgO^). — This  substance  is  contained  in  and 
easily^  extracted  from  willow-bark. 

Tests, — 1.  To  a small  portion  of  salicin  placed  on  a white 
plate  or  dish  add  a drop  of  strong  sulphuric  acid;  a deep- 
red  color  is  produced. 

2.  Boil  salicin  with  dilute  sulphuric  acid  for  some  time  ; 
it  is  converted  into  saligenin  (C7Hg02)  and  glucose. 

+ H,0  = C,H,0,  + 

Salicin.  Water.  Saligenin.  Glucose. 

Examine  a portion  of  the  solution  for  grape-sugar  by  the 
copper  test. 

3.  To  another  portion  of  the  liquid,  carefully^  neutralized, 
add  a persalt  of  iron  ; a purplish-blue  color  is  produced,  due 
to  the  reaction  of  the  saligenin  and  the  ferric  salt. 

4.  Heat  a mixture  of  about  1 part  of  salicin,  1 of  red 
chromate  of  potassium,  of  sulphuric  acid,  and  20  of  water 
in  a test-tube ; a fragrant  characteristic  odor  is  evolved,  due 
to  the  formation  of  hydride  of  salicyl  (C^H^O^H),  an  essen- 
tial oil  identical  with  that  existing  in  meadow-sweet  {Spirse 
ulmaria)  and  in  heliotrope. 

2C,H,0,  + O,  = 2C,H,02H  -f  2H2O 

Saligenin.  Oxygen.  Hydride  of  Water. 

salicyl. 

Santonin  (0,5H,g03). — This  substance  is  a weak  acid,  insoluble  in 
ammonia,  but  forming  a soluble  calcium  salt.  From  a solution  of 
santonate  of  calcium  the  santonin  is  precipitated  by  acids.  Boiled 
for  some  time  with  dilute  sulphuric  acid  it  yields  87  per  cent,  of  an 
insoluble  resinous  substance  [santoniretin)  and'glucose  (Kosmann). 
Santonin  [Santoninum,  B.  P.  and  U.  S.  P.,  and  Trochiscz  Santo- 
ninz,  U.  S.  P.)  is  official.  It  is  soluble  in  an  aqueous  solution  of  twice 
its  weight  of  carbonate  of  sodium. 

Process. — The  process  for  its  preparation  consists  in  boiling  san- 
tomca,  B.  P.  and  U.  S.  P.  (the  unexpanded  flower-heads  of  an 
undetermined  species  of  Artemisia — A.  cizia,  U.  S.  P.),  with  milk  of 
lime  (whereby  santonate  of  calcium  is  formed),  straining,  precipita- 
ting the  santonin  or  santonic  acid  by  hydrochloric  acid  (acetic  acid, 
U.  8.  P.),  washing  with  ammonia  to  remove  resin,  dissolving  in  spirit 
and  digesting  with  animal  charcoal  to  get  rid  of  coloring-matter, 


THE  GLUCOSIDES. 


371 


setting  the  spirituous  solution  aside  to  deposit  crystals  of  santonin, 
and  purifying  by  recrystallization  from  spirit.  (Mialhe). 

Saponin  (Oi2H.,o07?)  is  a peculiar  glucoside  occurring  in  Soap- 
wort,  the  root  of  the  common  Pink,  and  many  other  plants  : its  solu- 
tion in  water,  even  though  very  dilute,  froths  like  a solution  of  soap. 
Pereira  considered  smilacin,  one  of  the  principles  of  the  supposed 
activity  of  Sarsaparilla  {Sarzce  Radix,  B.  P.,  Sarsaparilla,  U.  S. 
P.),  to  be  closely  allied  to,  if  not  identical  with,  saponin. 

Saponin  is  also  met  with  in  the  root  of  Polygala  Senega  {Senegce 
Radix,  B.  P.,  Senega,  U.  S.  P.),  though  the  active  principle  of 
senega  is  said  to  reside  in  polygalic  acid,  probably  a glucoside  de- 
rivative of  saponin. 

ScAMMONiN  — Boil  resin  of  scaminony  {Scam- 

monise  Resina^  B.  P.  and  U.  S.  P.)  with  dilute  sulphuric 
acid  for  some  time;  glucose  may  then  be  detected  in  the 
liquid,  a resinous  acid  termed  scammoniol  ?)  being 

produced  at  the  same  time. 

Natural  scammony  (Scammonium,  B.  P.  and  U.  S.  P.)  is  an  exu- 
dation from  incisions  in  the  living  root  [Scammonice  Radix,  B.  P.) 
of  Convolvulus  Scammonia,  It  contains  from  10  to  20  per  cent,  of 
gum.  The  British  official  resin  of  scammony  contains  no  gum,  and 
is  made  by  digesting  the  root  in  spirit,  adding  water,  distilling  off 
the  alcohol,  and  washing  the  residual  resin  with  hot  water  till  free 
from  gum. 

The  U.  S.  P.  process  consists  in  exhausting  scammony  in  alcohol, 
recovering  the  latter  by  distillation,  treating  the  residue  with  water, 
and  drying  the  separated  resin. 

Resin  of  scammony  is  soluble  in  all  proportions  in  ether.  Sul- 
phuric acid  slowly  reddens  it.  It  is  said  to  be  liable  to  adulteration 
with  resin  of  jalap,  guaiacum-resin,  and  common  rosin.  Resin  of  jalap 
is  insoluble  in  ether,  guaiacum-resin  is  distinguished  by  the  color 
tests  mentioned  under  Gfuaiacin,  and  rosin  by  the  action  of  sulphuric 
acid. 


QUESTIONS  AND  EXERCISES. 

739.  Define  glucosides,  ahd  mention  those  of  pharmaceutical  in- 
terest. 

740.  Draw  out  an  equation  illustrative  of  the  development  of  Oil 
of  Bitter  Almonds. 

741.  How  much  pure  amygdalin  will  yield  one  grain  of  real  hydro- 
cyanic acid  ? 

742.  'fo  what  does  Cherry-Laurel-water  owe  activity  ? Is  the  pre- 
paration trustworthy  ? 

743.  Mention  the  active  principle  of  Senna. 

744.  By  what  process  is  the  glucoside  of  the  purple  foxglove  pre- 
pared ? 


372 


ALCOHOL  AND  ALLIED  BODIES. 


745.  State  the  circumstances  under  which  Guaiacum-Eesin  and 
Jalap-Eesin  yield  glucose. 

746.  Mention  a test  for  guaiacum-resin. 

747.  How  may  the  adulteration  of  jalap-resin  by  rosin  be  detected  ? 

748.  Enumerate  the  tests  for  Salicin. 

749.  How^  is  santonin  officially  prepared  ? 

750.  Name  sources  of  saponin. 

751.  What  is  the  difference  between  Scammony  and  Eesin  of 
Scammony  ? 

752.  How  would  you  detect  resins  of  turpentine,  guaiacum,  or 
jalap,  in  resin  of  scammony  ? 


ALCOHOL  AND  ALLIED  BODIES. 

ALCOHOL. 

Formation  of  Alcohol. — Ferment  two  or  three  grains  of  sugar 
by  dissolving  in  a test-tube  full  of  water,  adding  a little  yeast  [Cere- 
visice  Fermentiim,  B.  P.,  Fermeyitum,  U.  S.  P.),  or  a piece  of  the 
so-called  German  or  dried  yeast,  and  setting  the  whole  aside  for  j 
several  hours  in  a warm  place  at  a temperature  of  70^  or  75^;  car-j 
bonic  acid  gas  is  evolved,  and,  if  the  tube  be  inverted  in  a small  dish  } 
containing  w^ater,  may  be  collected  in  the  upper  part  of  the  tube  and  ii 
subsequently  tested  : the  solution  contains  alcohol.  If  the  experi- 1 
ment  be  made  on  larger  quantities  (four  ounces  of  sugar,  one  of  yeast,  | 
and  a pint  of  water)  the  fermented  liquid  should  be  distilled,  one-half  i 
being  collected,  shaken  with  a little  lime,  soda,  or  potash,  to  neutral- 1 
ize  any  acetic  acid,  and  decompose  ethereal  salts,  and  again  distilled  I 
till  one-half  has  passed  over ; the  product  is  dilute  spirit  of  wine.  It 
may  be  still  further  concentrated  or  rectified  by  repeating  this  pro-  j 
cess  of  f ractional  distillation.  ! 

Both  cane-sugar  and  grape-sugar  yield  alcohol  by  fermentation, ! 
the  cane-sugar  probably  always  passing  into  grape-sugar  before  the  I 
production  of  alcohol  commences.  | 

= 2C,H5H0  + 2CO,  ! 

Grape-sugar.  Alcohol.  Carbonic 

acid  gas.  [ 

Traces  of  several  other  substances  are  simultaneously  produced  i 
[vide  ''  Kousel  Oil”  in  Index).  By  this  reaction  are  formed  the  spirit  j 
of  the  v^ious  kinds  of  wine,  beer,  and  liqueurs,  such  as  Orange  AVine  | 
{ Vinvim  Aiirantii,  B.  P.),  made  ‘‘  by  the  fermentation  of  a saccharine 
solution,  to  which  the  fresh  peel  of  the  bitter  orange  has  been : 
added;”  Sherry  Wine  [Vinum  Xericum,  B.  P.  and  U.  S.  P.),the! 
fermented  juice  of  the  grape;  Port  Wine  [Vinum  Portense,  U.  S. 
P.),  AVhiskey  [8'piritus  Frumenti,  U.  S.  P.),  containing  from  48  to  56  - 
per  cent,  of  pure  alcohol;  Spirit  of  My  rci  a or  Bay  Rum  [Spiritus\ 
Myrcice,  U.  S.  P.),  prepared  by  distilling  rum  with  leaves  of  Myrcia ' 
acris ; and  others. 

Varieties  of  Alcohol. — The  weak  spirit  concentrated  by  distilla-i 
tion  till  it  contains  84  per  cent,  by  weight  of  pure  alcohol  is  an 


ALCOHOL. 


673 


ordinary  article  of  commerce ; its  specific  gravity  at  60^  is  0.8382. 
This  is  common  Spirit  of  Wine,  the  Spiritus  RectificaUis  of  the 
British  Pharmacopoeia.  Alcohol,  U.  S.  P.,  has  sp.  gr.  0.835  ; Alco- 
hol Fortius,  U.  8.  P.,  sp.  gr.  0.817.  The  official  Proof  SpiriP 
[Spiritus  Tenuior,  B.  P.)  contains  49  per  cent,  by  weight  of  alcohol, 
and  is  made  by  diluting  100  volumes  of  Rectified  Spirit  with  water 
until  the  well-stirred  product  measures  156  volumes.  Sixty  volumes 
of  water  will  be  required  for  this  purpose,  the  liquids  occupying  less 
bulk  after  than  before  admixture.  In  the  language  of  the  Excise 
authorities  the  rectified  spirit  of  the  Pharmacopoeia  would  be  de- 
scribed as  “56  per  cent,  over  proof”  (56  per  cent.  0.  P.);  that  is  100 
volumes  contain  as  much  alcohol  as  is  present  in  156  volumes  of  proof 
spirit.  Obviously,  proof  spirit  may  be  made  by  diluting  with  water 
rectified  spirit  of  any  other  strength  than  that  mentioned  above. 
Thus  100  fluidounces  of  a spirit  of  “ seventy  over  proof”  may  be 
diluted  to  170,  or  the  same  quantity  of  a spirit  of  “fifty  over  proof” 
may  be  diluted  to  150,  and  so  on.  The  specific  gravity  of  proof 
spirit  at  60^  is  0.920.  [Alcohol  Dilutum,  U.  S.  P.,  has  sp.  gr. 
0.941.) 

Empirical  Formulce. — Compositiom,  of  Alcohol — Alcohol,  by 
quantitative  analysis,  is  found  to  contain  the  elements  carbon,  hydro- 
gen, and  oxygen  in  the  following  proportions: — 

Composition  of  Alcohol. 

Carbon  . . . 52.174  or -r- 12  = 4.348  or  2. 

Hydrogen  . . . 13.043  or-;-  1=  13.043  or  6. 

Oxygen  . . . 34.783  or 16  = 2.174  or  1. 


100.000 

From  centesimal  numbers  a formula  is  obtained  in  the  usual  way. 

Thus,  on  dividing  these  figures  by  the  atomic  weights  of  the  respec- 
tive elements  (C  = 12,  II  = 1,  0 = 16),  and  reducing  the  products  to 
the  simplest  whole  numbers,  alcohol  will  be  found  to  contain  two 
atoms  of  carbon  to  every  six  of  hydrogen  and  to  every  one  of  oxygen, 
and  its  possible  or  empirical  formula  to  be  C2HgO. 

Constitution  of  Alcohol. — There  is  good  reason  to  believe  that 
alcohol  is  the  hydrate  of  a basylous  radical  ethyl  (C^H^  or  Et) ; hence 
we  derive  the  rational  formula  O2H.HO  or  EtHO. 

Rational  Formuloe. — Rational  formulae  are  deduced  by  (1)  ascer- 
taining how  much  of  the  substance  will  continue  with,  displace  or 
play  the  part  of,  the  atomic  weight  of  a well-known  elemenl^r  radi- 
cal. When  this  method  cannot  be  applied,  or  in  confirmation  of  it, 
processes  of  (2)  reduction,  (3)  oxidation,  (4)  substitution,  etc.,  are 
employed. 

* Proof  spirit  is  so  termed  from  the  fact  that  in  olden  times  a proof 
of  its  strength  was  supposed  to  be  afforded  by  moistening  a small  jfck. ^ 
quantity  of  gunpowder  and  setting  light  to  the  spirit:  if  it  fired  the 
powder  it  was  said  to  be  “ over  proof  if  not,  “ under  proof.”  The 
weakest  spirit  that  would  stand  this  test  was  what  we  should  now 
describe  as  of  sp.  gr.  0.920. 

32 


374 


ALCOHOL  AND  ALLIED  BODIES. 


Salts  of  Ethyl. — Alcohol  is,  then,  a body  analogous  in  constitu- 
tion to  hydrate  of  potassium  (KHO) ; and  there  are  other  compounds 
of  ethyl  analogous  in  constitution  to  ordinary  inorganic  salts,  such 
as  those  of  potassium.  The  oxide  of  ethyl  (Et^O)  is  common  ether; 
the  nitrite  of  ethyl  (EtN02)  is  the  body  which,  dissolved  in  spirit  of 
wine,  constitutes  “ sweet  spirit  of  nitre  the  acid  sulphate  of  ethyl 
(EtHS04),  or  sulphethylic  or  sulphovinic  acid,  is  a liquid  met  wdth 
in  the  preparation  of  ether.  The  iodide  (EtI),  hydride  (EtH),  ace- 
tate (EtA)  and  other  salts  are  of  considerable  chemical  interest,  but 
not  used  in  medicine. 

Absolute  or  Real  Alcohol  (C.^H^HO)  may  be  prepared  from 
spirit  of  wine  by  removing  the  water  which  the  latter  contains. 
This  is  accomplished,  partially,  by  the  agency  of  carbonate  of  potas- 
sium, and  finally  and  entirely  by  recently  burned  quicklime.  In 
operating  on,  say,  one  pint,  1^  ounce  of  dried  carbonate  of  potas- 
sium is  placed  in  a bottle  that  can  be  w^ell  closed,  and  frequently 
shaken  during  two  days  with  the  spirit.  Meanwhile,  about  half  a 
pound  of  good  quicklime,  if  not  already  at  hand,  is  made  from  10  or 
11  ounces  of  slaked  lime  by  heating  to  redness  in  a covered  crucible 
for  half  an  hour.  The  spirit  having  been  decanted  from  the  denser 
aqueous  solution  of  carbonate  of  potassium  and  placed  in  a quart 
flask,  retort,  or  tin  can,  the  lime,  as  soon  as  cold,  is  added,  and  the 
whole  occasionally  shaken  during  a day.  The  vessel  is  now'  placed 
in  a saucepan  or  other  bath  containing  w'ater,  quickly  connected 
with  a condenser  (in  the  case  of  the  flask  or  can  by  a bent  tube  and 
cork  previously  prepared;  for  absolute  alcohol  must  not  be  exposed 
to  air,  or  w'ater  in  the  form  of  moisture  will  be  rapidly  reabsorbed) 
and  heat  applied  to  the  bath.  Eejecting  the  first  ounce  or  ounce 
and  a half,  as  likely  to  contain  traces  of  moisture  absorbed  from  the 
air  or  apparatus,  continue  distillation  until  nothing  more  passes  over, 
the  W'ater  in  the  bath  being  kept  just  below  the  boiling-point  (about 
200°  F.).  These  details  are  those  of  the  British  Pharmacopoeia. 
Specific  gravity  0.7938.  Boiling-point  173.6. 

Tests. — There  are  no  specific  tests  for  alcohol  w'hen  mixed  w'ith 
complex  matters.  It  is,  however,  easily  isolated  and  concentrated 
by  fractional  distillation,  and  is  then  recognizable  by  conjoint  physi- 
cal and  chemical  characters.  Thus  its  odor  and  taste  are  character- 
istic ; it  is  lighter  than  w'ater,  volatile,  colorless,  and,  when  tolerably 
strong,  inflammable,  burning  with  an  almost  non-luminous  flame ; it 
readily  yields  aldehyd  (see  below)  and  acetic  ether  [vide  p.  268), 
each  of  w'hich  has  a characteristic  odor ; lastly,  in  presence  of  hot 
acid,  alcohol  reduces  red  chromate  of  potassium  to  a green  salt  of 
chromium. 

According  to  Lieben  1 of  alcohol  in  2000  of  w'ater  can  be  detected 
by  adding  to  some  of  the  w'arme)i.diquid  a little  iodine,  a few  drops 
of  solution  of  soda,  again  w'arming  gently,  and  setting  aside  for  a 1 
time  ; a yellow'ish  crystalline  deposit  of  iodoform  (Clllg)  is  obtained,  i 
Under  the  microscope  the  latter  presents  the  appearance  of  hexago-  j 
nal  plates  or  six-rayed  and  other  varieties  of  stellar  crystals.  i 

+ 41^  + 6NaIIO  = CIII3  + NaCHO.^  + 5NaI  + 5U,0.  j 


A L D E H Y D . 


375 


Otlier  alcohols,  aldehyds,  gum,  turpentine,  sugar,  and  several  other 
substances  give  a similar  reaction. 

Tests  of  purity. — Oil  of  resin  is  precipitated  on  diluting  spirit  of 
wine  with  distilled  water,  giving  an  opalescent  appearance  to  the 
mixture.  The  specific  gravity  should  be  0.838.  Fusel  oil,  aldehyd, 
and  aldehydic  acid  are  detected  by  nitrate  of  silver  {vide  Index, 

Alcohol,”  test  for  purity  of).  Water  in  absolute  alcohol  maybe 
detected  by  adding  to  a small  quantity  a little  highly  dried  sulphate 
of  copper,  which  becomes  blue  (CuSO^.fiH.^O)  if  water  is  present,  but 
retains  its  yellowish- white  anhydrous  character  (CuSOJ  if  water  be 
absent. 

Aldehyd  (C2H^0). — Place  together,  in  a capacious  test- 
tube,  or  a flask,  spirit  of  wine,  black  oxide  of  manganese, 
sulphuric  acid,  and  water,  and  gently  warm  the  mixture; 
aldeh3^d  (aZcohol  cZc/iy^Zrogenatus),  a highly  volatile  liquid, 
is  immediately  formed,  and  its  vapor  evolved,  recognized 
by  its  peculiar,  somewhat  fragrant  odor.  Adapt  a cork 
and  rather  long  bent  tube  to  the, test-tube,  and  let  some  of 
the  aldehyd  slowly  distil  over  into  another  test-tube,  tlie 
condensing-tube  being  kept  as  cool  as  possible.  Set  the 
distillate  aside  for  a day  or  two  ; the  aldehyd  will  have 
nearly  all  disappeared,  and  acetic  acid  be  found  in  the 
tube.  Test  the  exposed  liquid  by  litmus  paper;  it  will  be 
found  to  have  an  acid  reaction  : make  it  slightly  alkaline 
by  a drop  or  two  of  solution  of  carbonate  of  sodium,  then 
boil  to  remove  an}’  alcohol  and  aldehyd  present,  add  sul- 
phuric acid,  and  notice  the  characteristic  odor  of  the  acetic 
acid  evolved. 

These  experiments  will  enable  the  process  of  acetification  described 
in  connection  with  acetic  acid  to  be  more  fully  understood.  Pure 
diluted  alcohol  is  not  oxidized  by  exposure  to  air ; but  in  presence 
of  fermentive  matter,  or  vegetable  matter  undergoing  decay  or 
change,  it  is  oxidized  first  to  aldehyd  and  then  to  acetic  acid. 

In  the  above  process  the  black  oxide  of  manganese  and  sulphuric 
acid  furnish  nascent  oxygen  : — 

MnO^  + H2SO4  = MnSO,  + 0 -f  B,0 

Black  oxide  Sulphuric  Sulphate  of  Oxygen  Water, 

of  manganese,  acid,  manganese.  (atom). 

The  nascent  oxygen  then  acts  on  the  alcohol,  just  as  the  oxygen  of 
the  air  acts  on  the  alcohol  in  fermented  infusion  of  malt,  beer,  or 
wine,  giving  aldehyd  : — 

C^H.O  + 0 = C^H^O  + H.O 

Alcohol.  Oxygen  Aldehyd.  Water. 

(atom). 

The  aldehyd  rapidly,  even  when  pure  (more  rapidly  when  impure), 
absorbs  oxygen  and  yields  acetic  acid : — 

2C2H,0  + O2  = 2C.JI,0.2 

Aldehyd.  Oxygen.  Acetic  acid." 


376 


ALCOHOL  AND  ALLIED  BODIES. 


Tests. — Aldeliyd  heated  with  solution  of  potash  gives  a brownish-* 
yellow  resinous  mass  of  peculiar  odor.  Its  aqueous  solution  reduces 
salts  of  silver,  giving  a mirror-like  coating  to  the  sides  of  a test-tube. 

Spirit  of  French  Wine  {Spiritus  Vini  Gallici,  B.  P.  and  U.S.  P.) 
or  Brandy  is  a colored  and  flavored  variety  of  alcohol  distilled  from 
French  wine.  Its  color  is  that  of  light  sherry,  and  is  derived  from 
the  cask  in  which  it  has  been  kept,  but  is  commonly  deepened  by  the 
addition  of  burnt  sugar.  Its  taste  is  due  to  the  volatile  flavoring 
constituent  of  the  wine,  often  increased  by  the  addition  of  artificial 
essences.  It  should  contain  from  48  to  56  per  cent,  of  alcohol. 


QUESTIONS  AND  EXERCISES. 

753.  Write  a few  sentences  on  the  formation,  purification,  and 
concentration  of  alcohol,  and  explain  the  difference  between  Recti- 
fied Spirit,  Proof  Spirit,  and  Absolute  Alcohol. 

754.  AYhat  quantity  of  water  must  be  added  to  one  gallon  of  spirit 
of  wine,  56  degrees  over  proof,  to  convert  it  into  proof  spirit. 

755.  To  what  volume  must  5 pints  of  spirit  of  wine  of  53  degrees 
be  diluted  before  it  becomes  proof  spirit  ? — Ans.  7 pints,  13  ounces. 

756.  State  the  specific  gravity  of  proof  spirit. 

757.  Show  how  the  formula  of  alcohol  is  obtained  from  its  centesi- 
mal composition  : — 

Carbon  ' 52.174 

Hydrogen 13.043 

Oxygen 34.783 


100.000 

758.  Give  the  formulae  of  some  of  the  salts  of  ethyl. 

759.  By  Avhat  processes  may  pure  hydrate  of  ethyl  be  obtained  ? 

760.  Enumerate  the  characters  of  alcohol. 

761.  Mention  a chemical  test  to  distinguish  rectified  spirit  from 
absolute  alcohol. 

762.  From  the  formula  of  aldehyd  calculate  back  its  composition 
in  100  parts. 

763.  What  is  the  relation  of  aldehyd  to  alcohol  and  to  acetic  acid? 

764.  AVhence  is  brandy  obtained,  and  to  what  are  due  its  color 
and  flavor  ? 


ETHER. 

Formula  or  (C.^H5)^0,  or  Et^O. 

Experimental  Process. — Into  a capacious  test-tube  put 
a small  quantity  of  spirit  of  wine  and  about  half  its  bulk 
of  sulphuric  acid,  mix,  and  gently  warm  ; the  vapor  of 
ether,  recognized  by  its  odor,  is  evolved.  Adapt  a cork 


ET  HYLIC  ETHER. 


377 


and  long  bent  tube  to  the  test-tube  aud  slowly  distil  over 
the  ether  into  another  test-tube.  Half  the  original  quantity 
of  alcohol  now  placed  in  the  generating-tube  will  again 
give  ether;  and  this  operation  ma}"  be  re])eated  many 
times. 

On  the  lar'ge  scale,  and  according  to  the  following  official  process 
(jEther,  B.  P.  and  U.  S.  P.),  the  addition  of  alcohol,  instead  of  being 
intermitting,  is  continuous,  a tube  conveying  alcohol  from  a reservoir 
into  the  generating-vessel.  Mix  10  fluidounces  of  sulphuric  acid 
with  12  fluidounces  of  rectified  spirit  in  a glass  flask  capable  of  con- 
taining at  least  two  pints,  and,  not  allowing  the  mixture  to  cool, 
connect  the  flask  by  means  of  a bent  glass  tube  with  a Liebig’s  con- 
denser, and  distil  with  a heat  sufficient  to  maintain  the  liquid  in 
brisk  ebullition.  If  a thermometer  be  used  the  temperature  maybe 
still  more  carefully  regulated — between  284^  and  290°  F.  As  soon 
as  the  ethereal  fluid  begins  to  pass  over,  supply  fresh  spirit  in  a 
continuous  stream,  and  in  such  quantity  as  to  about  equal  the  volume 
of  the  fluid  which  distils.  For  this  purpose  use  a tube  furnished 
with  a stopcock  to  regulate  the  supply,  connecting  one  end  of  the 
tube  with  a vessel  containing  the  spirit  supported  above  the  level  of 
the  flask,  and  passing  the  other  end  through  the  cork  of  the  flask 
into  the  liquid.  When  a total  of  50  fluidounces  of  spirit  has  been 
added,  and  42  fluidounces  of  ether  have  distilled  over,  the  process 
may  be  stopped. 

To  partially  purify  the  liquid,  dissolve  10  ounces  of  chloride  of 
calcium  in  13  ounces  of  water,  add  half  an  ounce  of  lime,  and  agitate 
the  mixture  in  a bottle  with  the  impure  ether.  Leave  the  mixture 
at  rest  for  ten  minutes,  pour  off  the  light  supernatant  fluid,  and  dis- 
til it  with  a gentle  heat  until  a glass  bead  of  specific  gravity  0.735 
placed  in  the  receiver  begins  to  float.  The  ether  and  spirit  retained 
by  the  chloride  of  calcium  and  by  the  residue  of  each  rectification 
may  be  recovered  by  distillation  and  used  in  a subsequent  operation. 

Explanation  of  Process.^ — On  the  addition  of  sulphuric  acid  to 
alcohol  in  equal  volumes,  one  molecule  of  each  react  and  give  a 
molecule  of  sulphethylic  acid  and  one  of  water  : — 

EtHO  -f  = EtHSO,  + H,0 

Alcohol.  Sulphuric  Sulphethylic  Water, 

acid.  acid. 

More  alcohol  then  gives  ether  and  sulphuric  acid  by  the  reaction  of 
one  molecule  of  the  alcohol  on  one  of  sulphethylic  acid  : — 

EtHO  -f  EtHSO,  = Et20  + ^,^0, 

Alcohol.  Sulphethylic  Ether.  Sulphuric 

acid.  acid. 

The  water  of  the  first  reaction  and  the  ether  of  the  second  distil 
over,  while  the  sulphuric  acid,  as  fast  as  liberated,  is  attacked  by 
alcohol  and  reconverted  into  sulphethylic  acid  : — 

EtHO  -f  H,SO,  = EtHSO,  = B,0 

Alcohol,  Sulphuric  Sulphethylic  Water, 

acid.  acid. 


32* 


378 


ALCOHOL  AND  ALLIED  BODIES. 


SO  that  the  sulphuric  acid  originally  employed  finally  remains  in  the 
retort  in  the  form  of  sulphethylic  acid.  The  effect,  however,  of  a 
small  quantity  of  sulphuric  acid  in  thus  converting  a large  quantity 
of  alcohol  into  ether  is  limited,  secondary  reactions  occurring  to  some 
extent  after  a time. 

Pro'perties. — Pure  ether  is  gaseous  at  temperatures  above  95^  F. ; 
hence  the  condensing-tubes  employed  in  its  distillation  must  be  kept 
as  cool  as  possible.  At  all  ordinary  temperatures  it  rapidly  evapo- 
rates, absorbing  much  heat  from  the  surface  on  which  it  is  placed. 
A few  drops  evaporated  consecutively  from  the  back  of  the  hand 
produce  great  cold  ; if  blowm  in  the  form  of  spray,  the  cooling  effect 
is  so  rapid  and  intense  as  to  produce  local  anaesthesia.  Its  vapor  is 
very  heavy,  more  than  twdce  and  one-half  that  of  air  and  nearly  forty 
times  that  of  hydrogen  ; 0^1110=  74;  or  as  one  to  37).  In 

a still  atmosphere  therefore  it  will  flow  a considerable  distance  along 
a table  or  floor  before  complete  diffusion  occurs ; the  vapor  is  also 
highly  inflammable ; hence  the  importance  of  keeping  candle  and 
other  flames  at  a distance  during  manipulations  wdth  ether. 

Purification, — To  imitate  the  process  of  partial  purifica- 
tion above  described,  add  to  the  small  quantity  of  ether 
obtained  in  the  foregoing  operation  a strong  solution  of 
chloride  of  calcium  and  a little  slaked  lime ; the  latter 
absorbs  any  sulphurous  acid  that  may  have  been  produced 
by  secondaiy  decompositions,  while  the  former  absorbs 
water ; on  shaking  the  mixture  and  then  setting  aside  for 
a minute  or  two,  the  ether  will  be  found  floating  on  the 
surface  of  the  solution  of  chloride  of  calcium. 

This  ether,  redistilled  until  the  distillate  has  a sp.  gr.  not  higher 
than  0.735  (0.750,  U.  S.  P.)  and  boiling-point  not  higher  than  105*^ 
F.,  is  the  ether  of  ihe  British  Pharmacopoeia.  It  still  contains  about 
8 per  cent,  of  alcohol.  I’he  latter  may  be  removed  by  W'ell  shaking 
the  ether  with  half  of  its  bulk  of  water,  setting  aside,  separating  the 
floating  ether  and  again  shaking  it  with  w^ater ; alcohol  is  thus 
washed  out.  This  w^ashed  ether  containing  w^ater  (for  w’ater  and 
ether  are  to  some  extent  soluble  the  one  in  the  other;  50  measures 
agitated  with  an  equal  volume  of  water  are  reduced  to  45  by  an  | 
absorption  of  10  per  cent.)  is  next  placed  in  a retort  wdth  solid  chlo-  | 
ride  of  calcium  and  a little  caustic  lime,  and  once  more  distilled;  | 
pure  dry  ether  [jEtlier  Purus,  B.  P.,  JEther  Fortior,  U.  S.  P.)  ! 
results.  Sp.  gr.  not  exceeding  0.720  (0.728,  U.  S.  P.).  | 

Spiritus  jFtheris,  B.  P.,  is  a mixture  of  common  ether  {jFther,  \ 
B.  P.)  with  twice  its  bulk  of  rectified  spirit.  | 

NITROUS  ETHER,  OR  NITRITE  OF  ETHYL. 

Formula  EtNOg.  j 

Process, — To  a third  of  a test-tubeful  of  rectified  spirit  i 
add  about  a tenth  of  its  bulk  of  sulphuric  acid,  rather  more  : 


I 


NITROUS  ETHER. 


379 


of  nitric  acid,  and  some  copper-wire  or  turnings,  and  warm 
tlie  mixture  as  soon  as  ebullition  commences,  the  vapor  of 
nitrous  ether  is  evolved,  recognized  by  its  odor.  A long 
bent  tube,  kept  cool,  may  be  adapted  by  a perforated  cork 
to  the  test-tube,  and  thus  a few  drops  of  impure  nitrous 
ether  be  condensed  and  collected. 

The  above  process  conducted  on  a larger  scale,  with  definite 
quantities  of  materials,  temperature  regulated  by  a thermometer,  and 
a well-cooled  condenser,  is  the  official  (Redwood’s)  process  for  the 
preparation  of  a concentrated  solution  of  nitrous  ether  in  spirit ; di- 
luted with  nearly  three  times  its  bulk  of  rectified  spirit  it  forms  the 
“ sw^eet  spirit  of  nitre”  [Spiritus  ^Jtheris  Nitrosi,  B.  F.  and  U.  S. 
P.)  of  pharmacy. 

“ Take  of 

Nitric  Acid 3 fluidounces, 

Sulphuric  Acid 2 fluidounces, 

Copper,  in  fine  wire  (about  No,  25)  2 ounces, 

Rectified  Spirit a sufficiency. 

“To  one  pint  of  the  spirit  add  gradually  the  sulphuric  acid,  stir- 
ring them  together ; then  add,  in  the  same  way,  two  and  a half  ounces 
of  the  nitric  acid.  Put  the  mixture  into  a retort  or  other  suitable 
apparatus,  into  which  the  copper  has  been  introduced,  and  to  which 
a thermometer  is  fitted.  Attach  now  an  efficient  condenser,  and,  ap- 
plying a gentle  heat,  let  the  spirit  distil  at  a temperature  commenc- 
ing at  170^  and  rising  to  175^,  but  not  exceeding  180^,  until  12 
fluidounces  have  passed  over  and  been  collected  in  a bottle  kept  cool, 
if  necessary,  with  ice-cold  water ; then  withdraw  the  heat,  and,  having- 
allowed  the  contents  of  the  retort  to  cool,  introduce  the  remaining 
half  ounce  of  nitric  acid,  and  resume  the  distillation  as  before,  until 
the  distilled  product  has  been  increased  to  15  fluidounces.  Mix  this 
with  tw^o  pints  of  the  rectified  spirit,  or  as  much  as  will  make  the 
product  correspond  to  the  tests  of  specific  gravity  and  percentage  of 
liquid  separated  by  chloride  of  calcium  (vide  infra).  Preserve  it  in 
well-closed  vessels. 

Disregarding  secondary  products  (including  much  aldehyd),  the 
following  equation  probably  represents  decompositions  that  occur  in 
the  operation.  The  main  point  in  the  reaction  is  the  reduction  of 
the  nitric  to  the  nitrous  radical  by  the  indirect  a^gency  of  the  copper. 

EtHO  4-  HNO3  + + Cu  = EtNO^-P  + CuSO^ 

Alcohol.  Nitric  Sulphuric  Copper.  Nitrous  Water.  Sulphate  of 
acid.  acid.  ether.  copper. 

Properties. — Spirit  of  Nitrous  Ether  “is  transparent  and  nearly 
colorless,  with  a very  slight  tinge  of  yellow,  mobile,  inflammable,  of 
a peculiar  penetrating  apple-like  odor,  and  sweetish,  cooling,  sharp 
taste.  Specific  gravity,  0.845.  It  effervesces  feebly,  or  not  at  all, 
wdien  shaken  with  a little  bicarbonate  of  soda”  (showing  absence  of 
appreciable  quantities  of  free  nitrous,  acetic,  or  other  acids).  The 
aldehyd  in  it  may  be  detected  by  the  potash  test  (see  page  376). 

Test, — The  nitrous  radical  may  be  detected  by  adding  sulphate  of 


380 


ALCOHOL  AND  ALLIED  BODIES. 


iron  and  sulphuric  acid  to  some  of  the  spirit  of  nitrous  ether,  a brown 
or  black  compound  being  produced,  already  explained  in  connection 
with  nitric  acid  (p.  256). 

Test  of  Strength. — To  some  of  the  official  Spirit  of  Nitrou« 
Ether  add  twice  its  bulk  of  a saturated  solution  of  chloride 
of  calcium  and  mix  the  liquids  ; on  setting  aside,  nitrous 
ether  will  rise  to  the  surface.  If  the  spirit  of  nitrous  ether 
be  of  official  strength,  not  less  than  2 per  cent,  of  its  vol- 
ume will  thus  separate,  indicating  the  presence  of  10  per 
cent,  of  the  ether,  8 per  cent,  being  said  to  be  still  in  solu- 
tion. A graduated  tube  is  obviously  most  convenient  for 
this  purpose. 

Spiritiis  jTJtheris  Nitrosi^  U.  S.  P.,  has  the  specific 
gravity  0.837,  and  contains  five  per  cent,  of  nitrous  ether. 

Iodide  of  Ethyl  (EtI)  may  be  prepared  by  mixing 
amorphous  phosphorus  with  absolute  alcohol  and  then  add- 
ing iodine. 

5EtHO  + PI3  = 5EtI  + H,PO,  + H^O 

Alcohol.  Iodide  of  Iodide  of  Phosphoric  Water, 
phosphorus,  ethyl.  acid. 

The  reaction  at  first  proceeds  rapidly,  and  is  complete 
after  the  mixture  has  been  set  aside  for  a few  hours.  The 
iodide  of  ethyl  may  then  be  isolated  by  careful  distillation, 
freed  from  any  excess  of  iodine  by  washing  with  a very 
small  quantity  of  solution  of  potash  or  soda,  washed  with 
water,  dried  over  chloride  of  calcium,  and  again  distilled. 
It  should  be  kept  in  a dark  place,  as  light  favors  decompo- 
sition and  liberation  of  iodine. 

Ethyl. — This  gaseous  radical,  (0.^115)2  or  Et^,  is  obtained  ! 
on  digesting  together  at  about  250°  F.,  in  a strong  sealed 
tube,  dry  freshly  granulated  zinc  with  iodide  of  eth}’! 
(Frankland). 

Zn  + 2EtI  = Znl,  + Et, 

Zinc.  Iodide  of  Iodide  of  Ethyl, 

ethyl.  zinc. 

On  cautiousl}'  opening  the  tube  the  ethyl  escapes,  and  may 
be  ignited  or  collected  over  water.  There  remains  with 
the  iodide  of  zinc  a body  termed  by  Frankland  zinc-ethyl  | 
(ZnEtJ  ; it  is  a spontaneously  inflammable  liquid,  but  may  j 
easily  be  distilled  and  otherwise  manipulated  if  a few  sini-  i 
|)le  precautions  be  observed.  If  water  be  allowed  to  flow  > 
down  the  tube,  the  solid  compound  of  iodide  of  zinc  and  i 
zinc-ethyl  will  be  decomposed,  a gas,  hydride  of  ethyl  1 


OTHER  ALCOHOL  RADICALS. 


381 


(Etll),  resulting,  which  also  may  be  inflamed  or  collected 
over  water ; — 

ZnEt^  + = Zn2HO  + 2EtH. 


QUESTIONS  AND  EXERCISES. 

765.  Describe  the  official  process  for  the  preparation  of  Ether, 
giving  equations. 

766.  Offer  a physical  explanation  of  the  mode  of  producing  local 
anaesthesia. 

767.  How  is  commercial  ether  purified  ? 

768.  Explain  Redwood’s  process  for  the  preparation  of  “sweet 
spirit  of  nitre.” 

769.  Give  the  properties  of  spirit  of  nitrous  ether. 

770.  By  what  method  is  the  strength  of  “sweet  spirit  of  nitre” 
estimated  ? 

771.  How  is  iodide  of  ethyl  made  ? 

772.  Adduce  evidence  of  the  existence  of  ethyl. 


OTHER  ALCOHOL  RADICALS  AND  THEIR  SALTS. 

What  has  been  stated  concerning  the  chemistry  of  ethyl  and  its 
compounds  may  be  applied  to  other  radicals  known  to  exist,  some  of 
the  compounds  of  each  of  which  are  of  common  occurrence.  These 
basylous  radicals  are  closely  related  to  each  other,  to  hydrogen,  and 
to  the  metals.  Starting  from  hydrogen,  their  formulae  may  be  built 
up  by  successive  additions  of  OH2,  thus  : — 


Hydrogen 

. . . H 

Methyl 

. . . CH„ 

or  Me 

Ethyl  

. . . 

or  Et 

Propyl  (or  Trityl)  . . . 

. . . O3H,, 

or  Pr 

Butyl  (or  Tetryl)  . . . 

. . . C,H„ 

or  Bu 

Amyl  

. . . C,H„, 

or  Ay 

Caproyl  (or  Hexyl)  . . . 

or  Cp 

The  above  list  is  an  illustration  of  an  homologous  series  (from 
o/x6j,  homos,  the  same,  and  T^oyo^,  logos,  description)  of  compounds. 
It  will  be  observed  that  the  relation  of  the  number  of  hydrogen  atoms 
to  carbon  is  twice  as  many  with  one  added ; hence  the  series  is  often 
termed  the  C,,H2„+i  series  {n  = any  number).  The  oxides  of  these 
radicals  are  known  as  ethers,  their  hydrates  alcohols,  their  compounds 
with  the  acetic  and  similar  acidulous  radicals  ethereal  salts.  Every 
alcohol  furnishes  a body  corresponding  to  the  aldehyd  of  spirit  of 
wine,  the  class  being  termed  aldehyds  ; each  also  yields  an  acid  cor- 


382 


ALCOHOL  AND  ALLIED  BODIES. 


responding  with  acetic  acid.  Any  one  of  these  classes  constitutes 
an  homologous  series.  Or,  taking  the  hydride,  oxide,  hydrate,  acid, 
of  any  single  radical,  we  get  a heterologous  (EVfpo^,  heteros,  another) ' 
series  of  compounds.  Hydride  of  methyl  (MeH  or  CHgH)  is  ordi- 
nary marsh-gas,  fire-damp,  or  light  carhuretted  hydrogen  ; it  is  a 
diluent  or  non-luminiferous  constituent  of  ordinary  coal-gas  to  the 
extent  of  30  to  40  per  cent.  ;*  formic  acid,  the  acid  of  the  methyl 
series ; butyric  acid,  the  acid  of  the  butyl  series ; sulphocyanate  of 
butyl,  the  essential  oil  of  horseradish ; valerianic  acid,  the  acid  of 
the  amyl  series. 

Homologous  and  Heterologous  Series  of  the  Radicals, 


Radicals. 

Hydrides. 

Oxides 
(or  ethers). 

Hydrates 
(or  alco- 
hols). 

Aldehyds. 

Acids. 

(C  H3 ), 
(CA  ), 

(C3H, ), 

(C.H, ), 

etc. 

C H,  H 
O3H5  H 
C3H,  H 

cah 

OaHnH 

etc. 

(C  H3  ),0 
(CA 

(C3H,  )30 

(O.H,  )30 

(C5H„)30 

etc. 

C H3HO 
C2H5  HO 
CgH,  HO 
C.IIg  HO 
C5H,,H0 
etc. 

0 H,  0? 

C3H;  0 

0,H3  0 

c;h3  0 

O5H30O 

etc. 

0 H.3  0.3 

C3H,  0.3 
C3H3  0.3 
C3H3  0.3 
C5H.0O3 

etc. 

QUESTIONS  AND  EXERCISES. 

773.  Mention  several  radicals  homologous  with  ethyl,  and  give 
their  formulae. 

774.  Define  ethers,  hydrides,  alcohols,  ethereal  salts,  aldehyds. 

775.  What  is  the  difiPerence  between  homologous  and  heterologous 
series  ? 

776.  Give  the  systematic  name  of  fire-damp. 

777.  Enumerate  the  chief  constituents  of  coal-gas. 

778.  State  the  formulae  of  formic,  butyric,  and  valerianic  acids. 

779.  Write  the  formulae  of  butyl,  its  hydride,  ether,  alcohol,  alde- 
hyd,  and  acid. 

* Coal-gas. — The  other  diluents,  or  vehicles  for  the  illuminating 
constituents,  of  coal-gas  are  hydrogen  (40  to  50  per  cent.)  and  carbonic 
oxide  (6  to  7 per  cent).  The  illuminating  constituents  are  olefiant 
gas  (p.  394)  and  its  liornologues,  existing  to  the  extent  of  from  5 to  7 
per  cent.  The  impurities  are  nitrogen,  air,  carbonic  acid,  bisulphide 
of  carbon  CSg  (a  volatile  liquid  easily  made  from  its  elements),  and 
other  badly  smelling  sulphur  compounds.  Upwards  of  fifty  distinct  1 
cliemical  substances  have  been  obtained  from  the  solid,  liquid,  and  | 
gaseous  products  of  the  destructive  distillation  of  coal.  ! 


MET  HYLIC  ALCOHOL. 


383 


MYTHYLIC  ALCOHOL. 

Methylic  Alcohol  (CH^HO,  or  MeHO),  Wood-Spirit,  or  Py- 
ROXYLic  Spirit,  or  Wood-Naphtha,  is  a product  of  the  destructive 
distillation  of  wood.  Spirit  of  wine  containing  10  per  cent,  of  wood- 
spirit  constitutes  ordinary  methylated  spirit,  a spirit  issued  duty  free, 
for  the  use  of  manufacturers,  the  methylic  alcohol  not  interfering 
with  technical  applications.  From  its  nauseous  taste  and  odor,  how- 
ever, it  cannot  take  the  place  of  gin,  brandy,  or  other  spirit ; hence, 
while  industry  is  benefited,  intemperance  is  discouraged  and  the 
revenue  not  injured. 

Detection  of  Methylic  Alcohol  in  presence  of  Ethylic 
Alcohol. — Three  or  four  methods  have  been  proposed  for 
the  detection  of  methylated  spirit  in  various  liquids ; that 
open  to  least  objection  is  by  J.  T.  Miller.  For  the  applica- 
tion of  the  test  to  tinctures  and  similar  spirituous  mix- 
tures, some  of  the  spirit  is  first  separated  by  distilling  off 
a drachm  or  so  from  about  half  an  ounce  of  the  liquid 
placed  in  a small  flask  or  test-tube  having  a long  bent  tube 
attached.  Into  a similar  apparatus  put  30  grains  of  pow- 
dered red  chromate  of  potassium,  half  an  ounce  of  water, 
25  minims  of  strong  sulphuric  acid,  and  30  or  40  minims 
of  the  spirit  to  be  tested.  Set  the  mixture  aside  for  a 
quarter  of  an  hour,  and  then  distil  nearly  half  a fiuidounce. 
Place  the  distillate  in  a small  dish,  add  a very  slight  excess 
of  carbonate  of  sodium,  boil  down  to  about  a quarter  of 
an  ounce,  add  enough  acetic  acid  to  impart  a distinct  but 
feeble  acid  reaction,  pour  the  liquid  into  a test-tube,  add  a 
grain  of  nitrate  of  silver  dissolved  in  about  30  drops  of 
water,  and  heat  gently  for  a couple  of  minutes.  If  the 
liquid  then  merely  darkens  a little,  but  continues  quite 
translucent,  the  spirit  is  free  from  methylic  alcohol ; but  if 
a copious  precipitate  of  dark-brown  or  black  metallic  silver 
separates,  and  the  tube,  after  being  rinsed  out  and  filled 
with  clean  water,  has  a distinct  film  of  silver,  which  appears 
brown  by  transmitted  light  (best  seen  by  holding  it  against 
white  paper),  the  spirit  is  methylated. 

Explanation.— test  depends  for  its  action  on  the  reducing- 
powers  of  formic  acid.  In  the  above  operation  the  ethylic  alcohol 
becomes  oxidized  to  acetic  acid  (the  natural  acid  of  the  ethyl  series), 
which  does  not  reduce  silver  salts,  a minute  quantity  only  of  formic 
acid  being  produced,  while  the  methylic  alcohol  yields  formic  acid 
(the  natural  acid  of  the  methyl  series)  in  a comparatively  large 
quantity.  Aldehyd,  which  is  also  a reducing  agent,  is  simultaneously 
produced,  but  removed  in  the  subsequent  ebullition  with  carbonate 
of  sodium. 


884 


ALCOHOL  AND  ALLIED  BODIES. 


Methylated  Sweet  Spirit  of  Nitre. — The  preparation  of 
spirit  of  nitrous  ether  from  methylated  spirit  is  illegal  in 
Great  Britain,  but,  nevertheless,  occasionally  practised. 
For  the  detection  of  methylic  alcohol  in  this  liquid,  Mr. 
Miller  suggests  the  following  modification  of  the  above 
process. 

Shake  about  an  ounce  of  the  sample  with  20  or  30  grains 
of  anhydrous  carbonate  of  potassium,  and,  if  needful,  add 
fresh  portions  of  the  salt  until  it  ceases  to  be  dissolved, 
then  pour  off  the  supernatant  spirit.  This  serves  to  neutra- 
lize acid  and  to  remove  water,  in  which  some  samples  are 
remarkably  rich.  Introduce  half  a fluidounce  of  the  spirit 
into  a small  flask;  add  150  grains  of  anh3xlrous  chloride  of 
calcium  in  powder,  and  stir  well  together;  then,  having 
connected  the  flask  with  a condenser,  place  it  in  a bath  of 
boiling  water,  and  distil  a fluidrachm  and  a half,  or  con- 
tinue the  distillation  until  scarcely"  an^^thing  more  comes  " 
over.  The  operation  is  rather  slow,  but  needs  little  atten-  \ 
tion,  and  should  be  done  thoroughl>^  The  distillate  con-  | 
tains  nearly  the  whole  of  the  nitrous  ether  and  other  i 
interfering  substances.  Now  add  to  the  contents  of  the  I 
flask  a fluidrachm  of  water,  and  draw  over  the  half  drachm  | 
of  spirit  required  for  testing.  Add  to  it  the  usual  oxidiz-  j: 
ing  solution  composed  of  30  grains  of  red  chromate  of  ji 
potassium,  25  minims  of  strong  sulphuric  acid,  and  half  1 
an  ounce  of  water;  let  the  mixture  stand  a quarter  of  an  i 
hour,  then  distil  half  a fluidounce.  Treat  the  distillate  with  j 
a slight  excess  of  carbonate  of  sodium,  boil  rapidl}^  down 
to  two  fluidrachms,  and  drop  in,  cautiousl>^,  enough  acetic 
acid  to  impart  a faint  acid  reaction;  pour  the  liquid  into  a 
test-tube  about  three-quarters  of  an  inch  in  diameter;  add 
two  droi)S  of  diluted  acetic  acid,  and  one  grain  of  nitrate 
of  silver  in  half  a drachm  of  pure  water;  applj^  heat,  and 
boil  gentl^y  for  two  minutes.  If  the  spirit  is  free  from 
methylic  alcohol  the  solution  darkens  and  often  assumes  ; 
transiently  a purplish  tinge,  but  continues  quite  translu-  i 
cent,  and  the  test-tube,  after  being  rinsed  out  and  filled  I 
with  water,  appears  clean  or  nearly  so.  But  if  the  spirit  j 
contains  only  1 per  cent,  of  methvlic  alcohol  the  liquid  ! 
turns  first  brown,  then  almost  black  and  o[)aque,  and  a film  i 
of  silver,  which  is  brown  bj"  transmitted  light,  is  deposited 
on  the  tube.  When  the  sample  is  methylated  to  the  extent 
of  3 or  4 per  cent.,  the  film  is  sufficient!}^  thick  to  form  a 
brilliant  mirror.  To  insure  accuracy,  the  experiments  | 
should  be  performed  b}^  davlight. 


I 


CHLOROFORM. 


385 


CHLOROFORM. 

Formula  CHCI3. 

Process. — Should  the  necessary  appliances  be  at  hand, 
a small  quantit3^  of  this  liquid  may  easily  be  prepared  by 
the  official  process.  One  fluidounce  and  a half  of  spirit 
and  24  of  water  are  placed  in  a retort  or  flask  of  at  least 
a quart  capacity  ; 8 oz.  of  chlorinated  lime  and  4 of  slaked 
lime  are  added,  the  vessel  connected  with  a condenser, 
and  the  mixture  heated  until  distillation  commences,  the 
source  of  heat  then  being  withdrawn.  The  condensed  liquid 
should  fall  into  a small  flask  containing  water,  at  the  bot- 
tom of  which  about  a drachm  of  chloroform  will  slowly 
collect. 

Explanation  of  Process. — The  hypochlorite  of  calcium  (Ca2C10) 
believed  to  be  present  in  the  chlorinated  lime  (see  remarks  in  con- 
nection with  hypochlorous  acid)  readily  yields  up  oxygen  and  chlo- 
rine to  organic  substances,  the  calcium  being  liberated  as  hydrate, 
4(Ca2C10)  + 4H,0  = 4(Ca2H0)  + 20,4-4Ck.  The  alcohol  used 
in  making  chloroform  is  thus  reduced  first  to  aldehyd  : — 

2G,E,0  + 02  = 2C2H,0  + 2H2O 

Alcohol.  Oxygen.  Aldehyd.  Water. 

The  action  of  chlorine  on  aldehyd  then  probably  gives  chloral 
(chlor-aldehjd) : — 

C^H.O  + 3CI2  = C2HCI3O  + 3HC1 

Aldehyd.  Chlorine.  Chloral.  Hydrochl.  acid. 

The  hydrochloric  acid  being  at  once  neutralized  by  some  of  the 
liberated  hydrate  of  calcium  to  form  chloride  of  calcium  and  water, 
more  freed  hydrate  of  calcium  and  chloral  give  formate  of  calcium 
and  chloroform. 

2C._,HCl30  + Ca2H0  ==  Ca2CH02  + 2CHCI3 

Chloral.  Hydrate  of  Foimate  of  Chloroform, 

calcium.  calcium. 

Or,  neglecting  the  probable  steps  in  the  process,  and  regarding 

only  the  materials  and  the  products,  4 molecules  of  alcohol  and  8 of 

hypochlorite  of  calcium  give  2 of  chloroform,  3 of  formate  of  cal- 
cium, 5 of  chloride  of  calcium,  and  8 of  water,  thus  : — 

4C.2H,0  + 8CaCl20.2  = 2CHCl3+  3(Ca2CH02)  + 5CaCl2+  SH^O 

Alcohol.  Hypochlorite  Chloroform.  Formate  of  Chloiide  of  Water, 
of  calcium.  calcium.  calcium. 

The  hydrate  of  calcium  placed  in  the  generating-vessels  is  not  es- 
sential, but  is  useful  in  preventing  secondary  decompositions,  the 
hydrate  of  calcium  obtainable  from  the  reaction  being  insufficient  for 
this  purpose. 

Constitution. — Chloroform  is  sometimes  considered  to  be  the  chlo- 

33 


38G 


ALCOHOL  AND  ALLIED  B 


0 Jl 


ES. 


ride  of  a trivalent  radical  methenyl  (CH),  the  first  member  of  a 
series  Glycerine  is  the  hydrate  of  another  member— 

ceryl  or  propenyl,  O3H5  (p.  394). 

Chloroform  may  also  be  regarded  as  the  chloride  of  dichlor-methyl ; 
it  may  be  formed  from  methylic  compounds,  thus : — 

2CH,0  + 2(CaCl2,Ca01,02  = 2CHCI3  + CaCl,3CaO  + 3H3O 

Methylic  Chlorinated  Chloroform.  pxychloride  of  Water. 

alcohol.  lime.  calcium. 

Chlorine  converts  it  into  tetrachloride  of  carbon,  completing  a 
series  of  substitution  products  of  chloride  of  methyl. 


C 


H 

H 

H 


Cl 


Chloride  of 
methyl. 


c 


H 

H 

Cl 


Cl 


Chloride  of 
mono-chlor- 
methyl. 


c 


H 

Cl 

Cl 


Cl 


Chloride  of 
di-chlor- 
methyl. 


.1 


cn 

01  y 01  or  001, 
01 


Chloride  of  Tetrachloride 
tri-chlor-  or  of 
methyl  carbon. 


The  chloride  of  mono-chlor-methyl,  under  the  name  of  dichloride 
of  methylene,  has  been  used  as  an  anaesthetic.  It  may  be  obtained 
by  the  action  of  nascent  hydrogen  on  chloroform. 

Chloroform  is  purified  by  shaking  it  with  pure  sulphuric  acid 
containing  no  trace  of  nitric  acid,  which  chars  and  removes  hydro- 
carbons, but  does  not  affect  chloroform.  It  is  freed  from  any  trace 
of  acid  by  agitation  with  carbonate  of  sodium  and  from  moisture  by 
distillation  with  lime. 

Properties. — The  sp.  gr.  of  purified  chloroform  is  1.497  (1.480  U. 
S.  P.).  It  readily  and  entirely  volatilizes  with  characteristic  odor 
at  common  temperatures.  It  has  a sweetish  taste,  is  limpid,  color- 
less, soluble  in  alcohol  and  ether,  and  slightly  in  water,  but  burns 
with  a sluggish  green  smoky  flame. 

Iodoform  [lodoformum,  U.  S.  P.)  analogous  in  constitution  to 
chloroform,  the  iodine  taking  the  place  of  the  .chlorine  (CHI3),  is 
prepared  by  mixing  in  a retort  2 parts  of  carbonate  of  potassium,  2 
parts  of  iodine,  1 part  of  alcohol,  and  5 of  water,  heating  till  color- 
less, and  then  pouring  into  a beaker  and  allowing  to  settle.  The 
Iodoform  is  deposited  in  yellow  scales,  which  are  collected  on  a filter, 
washed  thoroughly  with  water  and  dried  between  filtering  paper. 

Iodoform  appears  in  the  shape  of  yellow,  shining  six-sided  scales 
with  a saffron-like  odor ; is  volatile  at  ordinary  temperatures,  and  at 
a temperature  above  250^  is  decomposed,  giving  off  violet  vapors. 
Almost  insoluble  in  water,  but  more  so  in  alcohol,  ether,  and  the 
fixed  and  volatile  oils. 


CHLORAL  AND  CHLORAL  HYDRATE. 

Process. — Pass  a rapid  stream  of  dry  chlorine  "into  pure  absolute 
alcohol  so  long  as  absorption  occurs.  During  the  first  hour  or  two 
the  alcohol  must  be  kept  cool,  afterwards  gradually  warmed  till  ulti- 
mately the  boiling-point  is  reached.  The  preparation  of  a consider- 
able f|uantity  occupies  several  days.  The  crude  product  is  mixed  1 
Avith  three  times  its  volume  of  oil  of  vitriol  and  distilled,  again  mixed  . 


CHLORAL. 


38T 


/ 


with  a similar  quantity  of  oil  of  vitriol  and  again  distilled,  and  finally 
rectified  from  quicklime. 

The  formation  of  chloral  would  at  first  sight  seem  to  be  due  to  the 
production  from  the  alcohol  (C.2HgO)  of  aldehyd  (OgH^O),  through 
the  removal  of  hydrogen  by  the  chlorine,  and  the  substitution  of 
chlorine  for  hydrogen  in  the  aldehyd  (02H^O)  with  formation  of 
chlor-aldehyd  or  chloral  (O^HCl^O).  But  the  reactions  are  far  more 
complicated,  being  somewhat  as  follows.  Aldehyd  and  hydrochloric 
acid  are  first  formed ; these  with  some  of  the  alcohol  give  monochlo- 

rinated  ether,  j- 0,  which  with  more  chlorine  yields  tetra- 


0 H 1 

chlorinated  ether,  GMCl  ( Og,  and  this  in  presence  of  water  fur- 
nishes chloral,  some  alcohol,  and  some  hydrochloric  acid  (Wurtz  and 
Vogt). 


Properties, — The  formula  of  chloral  is  C^HClgO.  It  is  a 
colorless  liquid,  of  oily  consistence.  Sp.  gr.  1.502.  Boiling- 
point  201.2.  Its  vapor  has  a penetrating  smell,  and  is 
somewhat  irritating  to  the  eyes.  Mixed  with  water  heat 
is  disengaged,  and  solid  white,  crystallizable,  hydrous  clilo- 
ral  {Chloral,^  U.  S.  P.),  or  what  is  more  generally,  though 
somewhat  irregularly,  termed  chloral  hydrate  (C^HCl.^O, 
H2O)  results.  The  latter  fuses  at  110.8  and  boils  at  293° 
F.  It  sublimes  as  a white  crystalline  powder.  Both 
chloral  and  chloral  hydrate  are  soluble  in  water,  alcohol, 
ether,  and  oils.  The  aqueous  solution  should  be  neutral, 
and  give  no  reaction  with  nitrate  of  silver.  Chloral  is 
said  sometimes  to  undergo  a spontaneous  change  into  an 
opaque  white  isomeric  modification,  insoluble  in  water, 
alcohol,  or  ether,  but  convertible  by  prolonged  contact 
with  water  or  by  distillation  into  the  ordinary  condition. 
By  action  of  weak  alkalies  chloral  first  yields  formiate  of 
the  alkali-metal  and  chloroform: — 


C2HCI3O  + KHO  = KCHO2  + CHCI3. 

Chloral,  or  rather  strong  aqueous  solution  of  chloral  hy- 
drate (3  in  4),  injected  beneath  the  skin  ^fields  nascent 
chloroform  by  action  of  the  alkali  of  the  blood,  and  pro- 
duces narcotic  effects  (Liebreich,  Person ne).  Chloroform 
itself  admits  of  similar  hypodermic  use  (Richardson).  If 
administered  by  the  stomach,  thirty  to  eighty  grains  of 
solid  hydrate  are  required.  The  final  products  of  the  re- 
action of  the  chloroform  and  blood  are  formiate  and  chloride 
of  sodium.  A spirituous  solution  of  potash  effects  the  same 
transformation. 


CHCI3  + 4KHO  = KCHO2  + 3KC1  -f  2H2O 


388 


ALCOHOL  AND  ALLIED  BODIES. 


Solution  of  ammonia  and  moist  hydrate  of  calcium,  as 
well  as  weak  solutions  of  fixed  alkalies,  convert  hydrate  of 
chloral  into  formiate  of  the  metal  and  chloroform.  The 
reaction  with  the  slaked  lime  being  especially  definite  and 
complete  (Wood),  it  may  be  employed  in  ascertaining  the 
richness  of  a sample  of  commercial  chloral  hydrate  in 
chemically  pure  chloral  hydrate. 

2(  C,HCl30, 11,0)  + Ca2H0  = 2CHCI3  + Ca2CH0,  + 2H,0. 


From  the  foregoing  equation  and  molecular  weights  it  is 
obvious  that  100  grains  of  hydrate  of  chloral,  if  quite  dry, 
will  yield  by  distillation  with  lime  and  a little  water  (in  a 
small  flask  and  long  bent  tube  kept  cool  by  moistened  paper) 
t2.2  grains  of  chloroform,  by  weight,  or  (the  sp.  gr.  of  chlo- 
roform being  taken  at  1.497)  47.56  grains  by  measure,  or 
about  52  minims. 

Pure  Chloral  Hydrate. — Liebreich,  who  first  proposed 
the  use  of  chloral  hydrate,  gives  the  following  as  the  char- 
acteristics of  a pure  article:  Colorless,  transparent.  Does 
not  decompose  by  the  action  of  the  atmosphere,  does  not 
leave  oily  spots  when  pressed  between  blotting-paper, 
affects  neither  cork  nor  paper.  Smells  agreeably  aromatic, 
but  a little  pungent  when  heated.  Taste  bitter  astringent, 
slightly  caustic.  Seems  to  melt  on  rubbing  between  the 
fingers.  Dissolves  in  water  like  candy  without  first  form- 
ing oily  drops.  Dissolves  in  bisulphide  of  carbon,  petro- 
leum, ether,  water,  alcohol,  oil  of  turpentine,  etc.  Boiling- 
point  203°  to  205°  F.  Distilled  with  sulphuric  acid,  the 
chloral  should  pass  over  at  205°  to  207°  F.  Melting-point 
133°  to  136°  F.  Gives  no  chlorine  reaction  on  treating 
the  solution  in  water  (acidulated  b3’'  nitric  acid)  with  nitrate 
of  silver. 

Impure  Chloral  Hydrate. — Yellowish,  cloud3^  Decom- 
poses ; leaves  spots  by  pressing  between  blotting-paper; 
decomposes  corks  and  paper  of  the  packing.  Smells  pun- 
gent and  irritating  ; on  opening  the  bottles  sticky  and  often 
emits  fumes.  Taste  strongly  caustic.  With  water  forms 
oily  drops  or  is  partially  insoluble.  Boils  at  a higher  tem- 
perature. On  treating  it  with  sulphuric  acid  turns  brown, 
with  formation  of  hydrochloric  acid.  Gives  chlorine  reac- 
tion on  treating  the  solution  in  water  (acidulated  by  nitric 
acid)  with  nitrate  of  silver. 


AMY  Lie  ALCOHOL. 


389 


Alcoholates  of  chloral  are  obtained  on  combining  alcohols 
with  chloral. 

Bromal  (C2HBr30),  hydrate  of  bromal  (C2HBr30,  H^O), 
alcoholates  of  bromal  produced  when  bromine  in- 
stead of  chlorine  attacks  alcohol. 


AMYLIC  ALCOHOL. 

Amylic  Alcohol  [Alcohol  Amylicum^'B.  P.  and  U.  S.  P.)  (C5HH 
HO,  or  AyHO)  is  a constant  accompaniment  of  ethylic  or  common 
alcohol  (O2H5HO,  or  EtHO)  when  the  latter  is  prepared  from  sugar 
which  has  been  derived  from  starch ; hence  the  name,  from  amylum 
starch.  The  sugar  of  potato-starch  yields  a considerable  quantity  ; 
hence  the  alcohol  is  often  called  potato-oi'L  It  is  also  termed  f ousel- 
oil,  or  fusel-oil  (from  ^vco,  phuo,  to  produce),  in  allusion  to  the  cir- 
cumstance that  the  supposed  oil  is  not  simply  educed  from  a sub- 
stance already  containing  it,  as  is  usually  the  case  with  oils,  but  is 
actually  produced  during  the  operation.  It  was  described  as  oil  pro- 
bably because  it  resembled  oil  in  not  readily  mixing  with  water  ; but 
it  is  soluble  to  some  extent  in  water,  and  is  a true  spirit,  homologous 
with  spirit  of  wine.  It  often  contains  variable  proportions  of  pro- 
pylic,  butylic,  and  caproylic  alcohols.  See  also  Valerianic  Acid. 

Amylic  alcohol  is  “ a colorless  liquid  with  a penetrating  and  op- 
pressive odor,  and  a burning  taste.  When  pure  its  specific  gravity 
is  0.818  ; boiling-point  279^.  Sparingly  soluble  in  water,  but  soluble 
in  all  proportions  in  alcohol,  ether,  and  essential  oils.  Exposed  to 
the  air  in  contact  with  platinum-black,  it  is  slowly  oxidized,  yielding 
valerianic  acid.”  Two  allotropic  varieties  of  amylic  alcohol  exist, 
one  dextro-rotating  a polarized  ray. 

Acetate  of  Amyl  (C5HJ1C2H3O2,  or  AyA).  To  a small 
quantity  of  amylic  alcohol  in  a test-tube  add  some  acetate 
of  potassium  and  a little  sulphuric  acid,  and  warm  the 
mixture;  the  vapor  of  acetate  of  amyl  is  evolved,  recog- 
nized by  its  odor,  which  is  that  of  the  jargonelle  pear.  If 
a conden sing-tube  be  attached,  the  essence  may  be  distilled 
over,  washed  by  agitation  with  water  to  free  it  from  alcohol, 
and  separated  by  a pipette. 

KA  -f  AyHO  + H2SO,  ==  AyA  + KHSO,  -+-  H2O 

Acetate  of  Amylic  Sulphuric  Acetate  of  Acid  sulphate  Water. 

potassium.  alcohol.  acid.  amyl.  of  potassium. 


Fruit- Essen  ces. 

Acetate  of  amyl,  prepared  with  the  proper  equivalent  proportions 
of  constituents  as  indicated  by  the  above  equation,  is  largely  manu- 
factured for  use  as  a flavoring  agent  by  confectioners.  Valerianate 
of  amyl  (Cj^Hi^C5H902)  is  similarly  used  under  the  name  of  apple-oil. 
Butyrate  of  ethyl  (O2M5C4H7O2)  closely  resembles  the  odor  and 


390 


ALCOHOL  AND  ALLIED  BODIES. 


flavor  of  the  pine-apple ; oenanthylate  of  ethyl  (C2H5C7Hj302)  re- 
calls green-gage;  pelargonate  of  ethyl  (^211509117702)  quince;  sube- 
rate  of  ethyl  (Et2C8Hi204)  mulberry  ; sebacate  of  ethyl  (Et2C7oHig04) 
melon.  Hydride  of  salicyl  (C7H5O2H),  or  salicylous  acid,  is  the 
essential  oil  of  meadow-sweet  {Spiroea  ulmaria),  and  maybe  prepared 
artificially  by  the  oxidation  of  salicin  [vide  p.  370).  Salicylate  of 
methyl  (CH3C7H5O3),  or  gaultheric  acid  [Oleum  gaultherice,  U.  S. 
P.),  is  the  essential  oil  of  winter-green  [Gaultheria  procumhens)^ 
and  may  also  be  prepared  artificially  from  salicin.  By  mixing  these 
ethereal  salts  with  each  other  and  with  essential  oils  in  various  pro- 
portions, the  odor  and  flavor  of  nearly  every  fruit  may  be  fairly 
imitated. 

Nitrite  of  Amyl  (C5H77N02). — For  the  preparation  of  this  sub- 
stance Maisch  recommends  a modification  of  Balard’s  process.  Amy- 
lic  alcohol  is  first  rectified  until  pure  ; that  is  until  its  boiling-point  is 
about  270^  F.  This  alcohol,  with  about  an  equal  bulk  of  nitric  acid, 
is  introduced  into  a capacious  glass  retort,  and  a moderate  heat  is  ap- 
plied and  very  gradually  increased.  As  soon  as  the  mixture  ap- 
proaches boiling,  the  fire  is  removed,  and  the  reaction  allowed  to 
continue.  If  the  application  of  the  heat  has  been  too  rapid  or  too 
long  continued,  considerable  frothing  occurs,  and  the  contents  of  the 
retort  are  apt  to  foam  over.  With  a moderate  and  slowly  increased 
heat,  the  reaction  is  less  violent  and  the  temperature  rises  gradually 
after  the  removal  of  the  fire  and  the  beginning  of  boiling.  As  soon 
as  the  thermometer,  inserted  in  the  tubulus,  rises  above  212^  F.,  the  i 
receiver  is  changed,  the  distillate  now  becoming  more  and  more  mixed  i 
wfith  ethyl-amylic  ether  and  nitrate  of  amyl,  readily  perceived  by  the  j 
change  in  odor. 

The  distillate  obtained  below  212^  F.  is  agitated  with  an  aqueous 
solution  of  caustic  or  carbonate  of  potassium  to  remove  free  acids, 
and,  after  separation,  the  oily  liquid  is  introduced  into  a clean  retort 
and  again  slowly  heated.  The  first  portion  coming  over  contains 
amylic  aldehyd.  When  the  very  slowly  increased  heat  has  risen  to 
205^  F.,  the  receiver  is  again  changed  and  the  distillate  now  collected 
as  nitrite  of  amyl,  until  the  thermometer  reaches  212^  F.,  when  the 
distillation  is  stopped.  I 


QUESTIONS  AND  EXERCISES.  j 

780.  Name  the  source  of  methylic  alcohol. 

781.  What  is  “methylated  spirit?”  j 

782.  Describe  the  method  by  which  methylated  spirit  is  detected  1 
in  a tincture. 

783.  In  what  relation  does  formic  acid  stand  to  methylic  alcohol?  i 

784.  How  would  you  proceed  to  ascertain  whether  or  not  a speci-  ; 

men  of  sweet  spirit  of  nitre  had  been  made  from  methylated  spirit  ? ' 

785.  Give  details  of  the  production  of  chloroform  from  alcohol,  i 
tracing  the  various  steps  by  equations. 


PHENYL,  CARBOLIC  ACID,  ETC. 


391 


786.  Is  chloroform  an  ethylic  compound  ? What  is  its  probable 
constitution  ? 

787.  How  is  chloroform  purified  ? 

788.  State  the  character  of  pure  chloroform. 

789.  Describe  the  reactions  that  occur  in  the  manufacture  of 
chloral  and  chloral  hydrate. 

790.  What  is  the  nature  of  the  action  of  alkalies  on  chloral 
hydrate  ? 

791.  Mention  the  characters  of  pure  and  impure  chloral  hydrate. 

792.  Whence  is  amylic  alcohol  obtained  ? 

793.  Has  valerianic  acid  any  chemical  relation  to  amylic  alcohol  ? 

794.  Mention  the  systematic  names  of  several  artificial  fruit- 
essences. 

795.  What  is  the  formula  of  nitrite  of  amyl,  and  how  is  it  pre- 
pared ? 


SALTS  AND  DERIVATIVES  OF  RADICALS  OF  OTHER 
SERIES  THAN  THE 

What  has  been  stated  regarding  radicals  having  the  general  for- 
mula C^H2«-j-i  and  their  salts,  may  be  applied  to  the  radicals  of  other 
series. 

The  series  C^H2„_7  includes  'phenyl  (CgH.),  the  hydride  of  which 
(CgHgH,  or  PhH)  is  common  benzol  (B.  P.),  a colorless  volatile 
liquid  obtained  from  coal-tar.  Toluol  (C^Hg),  or  methyl-benzol,  is 
one  of  the  products  of  the  distillation  of  balsam  of  Peru.  The  next 
homologue,  xylol  (CgH^g),  or  dimethyl-benzol,  is  contained  in  crude 
wood-spirit  and  in  coal-naphtha : it  is  a colorless  fiuid,  having  an 
odor  faintly  resembling  that  of  benzol ; boiling-point  282^  F. ; sp. 
gr.  .866.  Benzol  is  a powerful  solvent  of  grease,  and  under  the 
name  of  Benzine  Collas  was  introduced  by  M.  Collas,  in  1848,  for 
cleansing  stuffs.  By  the  action  of  strong  nitric  acid,  benzol  yields 
nitrohenzol  (CgH5(N02)),  a liquid  termed,  from  its  odor,  artificial 
oil  of  hitter  almonds,  or  essence  of  mirhane.  Its  specific  gravity  is 
1.20  to  1.29.  The  odor  of  this  essence,  however,  is  not  exactly  that 
of  essential  oil  of  almonds,  and  its  composition  is  very  different ; so 
that  it  is  not  truly  an  artificial  volatile  oil.  The  natural  oil  has  a 
sp.  gr.  of  1.04  to  1.07,  and  is  a hydride  of  the  negative  radical  ben- 
zoyl (C^HgOH),  a radical  derived  from  the  next  higher  homologue  of 
phenyl  by  displacement  of  hydrogen  by  oxygen.  Nitrobenzol  yields 
aniline  [vide  infra),  oil  of  bitter  almonds  does  not  (page  366).  The 
hydrate  of  phenyl  (CgH^HO),  or  phenic  alcohol,  or  phenol,  is  the 
phenic  acid  or  carbolic  acid  of  commerce  (Acidum  Carbolicum, 
U.  S.  P.),  a colorless  crystalline  substance,  obtained  from  coal-tar  oil 
by  fractional  distillation  and  subsequent  purification.  At  tempera- 
tures above  95^  F.  it  is  not  an  oily  liquid.  It  is  only  slightly  soluble 
in  water.  Aqua  Acidi  Carbolici,  U.  S.  P.,  but  readily  dissolved  by 
alcohol,  ether,  and  glycerine  [Glyceritum  Acidi  Carbolici,  U.  S. 
E^.).  In  odor,  taste,  and  solubility  (and  in  appearance  when  lique- 
fied by  heat  or  by  the  addition  of  5 per  cent,  of  water)  it  resembles 


392 


ALCOHOL  AND  ALLIED  BODIES. 


creasote,  a wood-tar  product  for  which  carbolic  acid  is  often  substi- 
tuted. Beside  hydrate  of  phenyl  (CgHgHO)  coal-tar  oil  contains 
cresol,  hydrate  of  cresyl,  or  cresylic  acid  (C^H^HO);  while  wood-tar 
oil  furnishes  guaiacol  (C7Hg02) — also  a product  of  the  destructive 
distillation  of  guaiacum-resin — and  crtasol  (CgHjQ02),  or  creasote. 
Certain  coloring-matters  may  be  obtained  by  the  oxidation  of  car- 
bolic acid ; ammonia  mixed  with  it,  and  then  a small  quantity  of 
solution  of  a hypochlorite  gives  a blue  liquid  ; a similar  effect  is  pro- 
duced on  dipping  a chip  of  deal  into  carbolic  acid  (or  into  creasote), 
then  into  hydrochloric  acid,  and  afterwards  exposing  it  to  the  air. 
By  the  following  tests  carbolic  acid  may  be  distinguished  from  crea- 
sote. The  former  boils  only  at  370'^,  while  the  latter  readily  dries 
up  at  212^.  Carbolic  acid  does  not  affect  a ray  of  polarized  light; 
creasote  twists  it  to  the  right.  Carbolic  acid  is  either  solid  or  may  be 
solidified  by  cooling ; creasote  is  not  solidified  by  the  cold  produced 
by  a mixture  of  hydrochloric  acid  and  sulphate  of  sodium.  Creasote 
from  coal  (impure  or  crude  carbolic  acid)  gives  a jelly  when  shaken 
with  collodion  ; creasote  from  viooiL  {Creasotum,  B.  P.  and  U.  S.  P.) 
is  unaffected  by  collodion  (Rust).  Coal-creasote  is  soluble  in  solution 
of  potash,  w^ooicreasote  insoluble.  The  coal  product  is  soluble  in  a 
large  volume  of  water,  and  a neutral  solution  of  ferric  chloride  strikes 
a blue  color  with  the  liquid;  wood-creasote  is  less  soluble  {Aq2ia 
Creasotz,  U.  S.  P.,  is  said  to  contain  1 in  129)  and  not  altered  by 
ferric  chloride.  An  alcoholic  solution  of  the  coal-oil  is  colored  brown 
by  ferric  chloride,  a similar  solution  of  true  creasote  green.  Accord- 
ing to  Mr.  Thomas  Morson  pure  creasote  is  unaffected  when  mixed 
with  an  equal  volume  of  commercial  glycerine  (it  is  soluble  in  pure 
anhydrous  glycerine — Fluckiger),  while  carbolic  acid  is  miscible  in 
all  proportions,  and  will  carry  into  solution  even  a considerable 
quantity  of  creasote.  Carbolic  acid  is  a pow^erful  antiseptic  (avrif 
anti,  against,  and  sepo,  to  putrefy).  In  large  doses  it  is  poison- 
ous, the  best  antidote  being  olive  oil  and  castor  oil,  freely  adminis- 
tered. Acidum  Carholicum  Impurum,  U.  S.  P.,  is  the  impure 
carbolic  acid  obtained  from  coal-tar  oil  by  treating  it  first  wfith  an 
alkali,  and  then  wfith  an  acid,  and  finally  distilling.  It  is  of  a browm 
shade,  and  if  at  first  colorless  it  becomes  reddish-brown  on  exposure. 
It  consists  of  carbolic  and  cresylic  acids  in  variable  proportion 
together  with  impurities  derived  from  coal-tar.  100  measures  of 
w^arm  water  on  being  agitated  with  one  measure  of  the  liquid 
will  dissolve  out  the  two  acids  and  should  not  leave  more  than  30 
per  cent,  by  measure  of  impurity.  Carbolic  acid  is  soluble  in  oil  of 
vitriol,  sulpho-carbolic  acid  (IICgH5S04)  or  sulphophenic  acid 
being  formed.  On  diluting  and  mixing  with  oxides,  hydrates,  or 
carbonates,  sulpliocarholates  are  formed.  The  formula  of  sulpho- 
carholate  of  sodium  is  NaC6H5S04;  sulphocarholate  of  zincZw 
(C(jH5S04)2H20.  Trinitro-carbolic  acid  (C6ll3(N02)30)  is  formed 
on  slowly  dropping  carbolic  acid  into  fuming  nitric  acid ; it  is  the 
yellow  dye  known  as  carhazotic  acid  or  picric  acid  ; most  of  the 
picrates  are  explosive  by  percussion.  Both  carbolic  acid  and  benzol 
are  secondary  products,  obtained  in  the  manufacture  of  coal-gas ; 
hence,  indeed,  the  w^ord  phenic,  and  thence  phenyl  (from 
phainb,  I light,  in  allusion  to  the  use  of  coal-gas).  Aniline,  or 


AL0IN8. 


393 


plienylamine,  is  a product  of  the  action  of  nascent  hydrogen  on 
nitrobenzol. 


Nitrobenzol.  Hydrogen. 


the  substance  whence,  by  oxidation,  &c.,  aniline-red  (magenta), 
-orange,  -yellow,  -green,  -blue,  -violet  (mauve),  and  -black  are  pro- 
duced. 

Aloins. — The  aloes  of  pharmacy  {Aloe  Barbadensts,  B.  P.,  and 
Aloe  Socotrma,  B.  P.)  is  an  evaporated  juice,  doubtless  much 
altered  by  the  temperature  to  which  it  is  subjected. 

Barhaloin,  C;^4H3g0j4H20. — This  substance,  first  obtained  by  T. 
and  H.  Smith,  occurs  in  minute  crystals  in  Barbadoes  and  Soco- 
trine  aloes.  It  is  readily  procured  from  the  former  by  dissolving 
in  boiling  water  acidified  with  a little  hydrochloric  acid,  after 
some  hours,  pouring  off  the  precipitated  resin  and  evaporating 
the  liquid  to  a syrup.  The  aloin*  crystallizes  out  in  a day  or  two. 
Barbaloin  yields  by  the  action  of  bromine  and  chlorine  substitu- 
tion compounds,  C34H3gBigOi^  and  Cg^HggClgOi^GH^O.  Nitric  acid 
dropped  upon  it  produces  a red  color,  which  soon  fades.  Boiled 
for  some  time  with  strong  nitric  acid  barbaloin  gives,  together 
with  oxalic  and  picric  acids,  a yellow  substance,  chrysammic  acid, 
Ci4H4(N02)404,  which  furnishes  beautiful  red  salts. 

Nataloin,  C)25H280ii. — This  body  was  discovered  by  Pluckiger 
in  Natal  aloes.  It  crystallizes  readily  in  rectangular  plates,  either 
from  spirit  or  from  water.  No  bromine  or  chlorine  substitution 
derivatives  have  yet  been  formed,  but  an  acetyl  compound 

O. 2511.2.2(021130 )60ii  (Tilden)  has  been  analyzed.  The  existence  of 
this  compound  serves  to  corroborate  the  formula  given  above. 
Nataloin  moistened  with  nitric  acid  gives  a red  coloration  which 
does  not  fade.  When  boiled  with  nitric  acid  it  yields  no  chrysammic, 
but  only  oxalic  and  picric  acids. 

The  reactions  of  these  two  bodies  seem  to  indicate  that  they  are 
complex  phenols.  Phenol  being  the  phenyl  hydrate,  CgH5,IIO,  and 
cresol  being  the  methyl-phenol,  CgH^,CH3,HO,  the  aloins  may  possi- 
bly have  a similar  constitution,  that  is,  they  may  be  the  hydrates  of 
radicals  in  which  part  of  the  hydrogen  is  replaced  by  groups  of 
atoms.  Anthracen,  has  been  obtained  by  deoxidation  of 

barbaloin. 

In  the  series  we  have  the  univalent  radical  allyl  (C3H5), 

whose  sulphide  ((03115)28)  is  essential  oil  of  garlic  {Allium,  U.  S. 

P. )  and  sulphocyanate  (C3ll5Cy8)  the  essential  oil  of  mustard. 
Mustard  {sinapis,  B.  P.  and  U.  8.  P.)  is  a powdered  mixture  of 
black  and  white  mustard-seeds.  The  white  mustard-seed  contains 
sinalbin  (C3oH^4N2820ig),  a glucoside  which,  in  contact  with  the 
aqueous  extract  of  mustard,  yields  some  acrid  oil.  The  black  con- 
tains a ferment  resembling  the  emulsin  of  almonds  (p.  366)  and  my- 
ronate  of  potassium.  The  latter  is  the  body  which,  under  the  influ- 
ence of  the  former,  yields  the  chief  part  of  the  oil. 


394 


ALCOHOL  AND  ALLIED  BODIES. 


K,C,oH33NAO,9  x=  2(KHS03)  + 2C3H,CNS  + 2C«H,,0,  + H,0 

Myronate  of  Acid  sulphate  Oil  of  Glucose.  Water. 

potassium.  of  potassium.  Mustard. 

Allyl  compounds  are  also  met  with  in  several  other  cruciferous  and 
liliaceous  plants. 

In  the  series  occurs  ethylene  or  olefiant  gas  (C2H^),  the 

chief  illuminating  constituent  of  coal-gas  (readily  made  on  heating 
alcohol  with  twice  its  volume  of  strong  sulphuric  acid),  a bivalent 
radical,  the  alcohol  of  which  is  glycol  (O2H42HO).  Etlierol,  or 
Ethereal  Oil  [Oleum  Ethereum,  U.  S.  P.),  or  light  oil  of  wine 
( CJ3H32?),  a hydrocarbon  polymeric  with  olefiant  gas,  is  one  of  the 
products  of  the  action  of  excess  of  sulphuric  acid  on  alcohol : its  sp. 
gr.  is  0.917.  In  the  the  trivalent  hypothetical  radical 

glyceryl  (C3II5)  is  found,  the  hydrate  of  which  (OgH^SHO)  is  glycerine. 
The  homologues  of  glycol  are  termed  glycols,  the  homologues  of 
glycerine  glycerines.  It  will  be  noticed  that  the  chemical  composi- 
tion of  the  radicals  glyceryl  and  allyl  is  identical  (C3H5),  but  the 
former  is  trivalent  and  the  latte;'  univalent ; hence  they  probably 
differ  in  physical  constitution  ; they  are  isomeric,  possibly  polymeric, 
with  each  other.  From  a glyceryl  compound  (glycerine),  however, 
an  allyl  salt  (iodide)  can  be  produced.  By  distilling  a mixture  of 
glycerine  and  diniodide  of  phosphorus,  iodide  of  allyl  (C3H5I)  is  ob- 
tained, and  on  digesting  this  with  sulphocyauate  of  potassium,  the 
sulphocyanate  of  allyl,  or  artificial  oil  of  mustard,  results ; identical 
with  the  natural  oil. 


Glycerine. 

Glycerine,  or  Glyceric  Alcohol  (O3II.3HO). — Glycerine  is  the 
hydrate  'of  glyceryl,  glycyl,  or  propenyl — the  basylous  radical  of 
most  oils  and  fats.  These  latter  are  mainly  oleates,  palmitates,  and 
stearates  of  glyceryl ; and  when  heated  with  metallic  hydrates  (even 
with  water — hydrate  of  hydrogen,  HHO — at  a temp,  of  500^  or 
600^  F.)  yield  oleate,  palmitate  or  stearate  of  the  metal,  and  hydrate 
of  glyceryl  or  glycerine.  Hence  glycerine  is  a by-product  in  the 
manufacture  of  soap,  hard  candles,  and  lead-plaster  [vide  Index). 

Properties. — Glycerine  is  viscid  when  pure,  specific  gravity  1.28 
(not  below  1.25,  B.  P.)  has  a sweet  taste,  is  soluble  in  water  or 
alcohol  in  all  proportions.  It  has  remarable  powers  as  a solvent,  is 
a valuable  antiseptic  even  when  diluted  with  10  parts  of  water,  and 
useful  as  an  emollient.  In  vacuo  it  may  be  distilled  unchanged  but 
under  ordinary  atmospheric  pressure  is  decomposed  by  heat. 

Test — Heat  one  or  two  drops  of  glycerine  in  a test-tube, 
alone  or  with  strong  sulphuric  acid,  acid  sulphate  of  potas- 
sium, or  other  salt  powerfully  absorbent  in  water;  vapors 
of  acrolein  (from  acer^  sharp,  and  oleum.,  oil)  are  evolved, 
recognized  by  their  powerfully  irritating  effects  on  the  eyes 
and  respiratoiy  passages.  If  the  glycerine  be  in  solution 
in  water,  it  must  be  evaporated  as  low  as  possible  before 
applying  this  test.  Besides  glycerine  itself  {Glycerinum^ 


a 


ALBUMENOID  SUBSTANCES. 


395 


B.  P.,  Glycerina^  U.  S.  P.),  there  are  several  official  prepa- 
rations of  glycerine — solutions  of  carbolic,  gallic,  and  tan- 
nic acids  and  borax  in  glycerine,  and  a sort  of  mucilage 
of  starch  in  glycerine  (Glyceritum  Acidi  Carbolici^  Gly~ 
ceritum  Acidi  Gallici^  Glyceritum  Acidi  Tannici^  Glyceri- 
tum Fids  Liquidse^  and  Glyceritum  Sodii  Boratis), 


QUESTIONS  AND  EXERCISES. 

<796.  Give  the  names  and  formulae  of  compounds  of  radicals  having 
the  general  formula  C„H2n-/",  and  — e.  g., 

benzol,  essential  oil  of  mustard,  glycerine,  and  glycol. 

797.  State  the  difference  in  composition  of  natural  and  artificial 
oil  of  bitter  almonds. 

798.  How  is  the  so-called  artificial  oil  of  bitter  almonds  prepared? 

799.  What  are  the  uses,  composition,  source,  and  properties  of 
Carbolic  Acid  ? 

800.  State  the  characters  by  which  carbolic  acid  is  distinguished 
from  Creasote. 

801.  In  what  relation  does  carbolic  acid  stand  to  cresylic  acid  ? 

802.  What  is  the  general  formula  of  sulphocarbolates  ? 

803.  Draw  out  an  equation  explanatory  of  the  production  of 
aniline. 

804.  Mention  the  chief  properties  of  Glycerine. 

805.  What  is  the  specific  gravity  of  glycerine  ? 

806.  By  what  test  is  glycerine  recognized  ? 

807.  Enumerate  some  official  preparations  in  which  glycerine  is 
employed  as  a solvent. 


ALBUMENOID  SUBSTANCES. 

Albumen, — Agitate  thoroughly,  white  of  egg  {Albumen 
Ovi^  B.  P.)  with  water,  and  strain  or  pour  off  the  liquid 
from  the  flocculent  membranous  insoluble  matter.  One 
white  to  4 ozs.  of  water  forms  the  ‘‘  Solution  of  Albumen,” 

B.  P. 

Test, — Heat  a portion  of  this  solution  of  albumen  to  the 
boiling-point ; the  albumen  becomes  insoluble,  separating 
in  clots  or  coagula  of  characteristic  appearance. 

Other  Reactions, — Add  to  small  quantities  of  aqueous 
solution  of  albumen  solutions  of  corrosive  sublimate, 
nitrate  of  silver,  sulphate  of  copper,  acetate  of  lead,  alum, 
perchloride  of  tin;  the  various  salts* not  only  coagulate 
but  form  insoluble  compounds  with  albumen.  Hence  the 


396 


ALBUxMENOlD  SUBSTANCES. 


value  of  an  egg  as  a temporary  antidote  in  cases  of  poi- 
soning by  many  metallic  salts,  its  administration  retarding 
the  absorption  of  the  poison  until  the  stomach-pump  or 
other  measures  can  be  applied.  Sulphuric,  nitric,  and 
hydrochloric  acids  precipitate  albumen  ; the  coagulum  is 
slowly  redissolved  by  aid  of  heat,  a brown,  yellow,  or  pur- 
plish-red color  being  produced.  Neither  acetic,  tartaric, 
nor  organic  acids,  generall}^,  except  gallo-tannic,  coagulate 
albumen.  Alkalies  prevent  the  precipitation  of  albumen. 

Y^olk  or  FeZA;  of  Egg  {Ovi  Vitellus,  B.  P.)  contains  only  3 per 
cent,  of  albumen — the  white  12^.  The  yolk  also  contains  only  30  per 
cent,  of  yellow  fat  and  14  of  casein.  The  whole  egg  ( Ovum,  U.  S.  P.) 
is  also  official. 

Albumen  is  met  wnth  in  large  quantities  in  the  serum  of  blood,  in 
smaller  quantity  in  chyle  and  lymph,  and  in  the  brain,  kidneys,  liver, 
muscles,  and  pancreas.  It  is  not  a normal  constituent  of  saliva, 
gastric  juice,  bile,  or  mucus,  but  occurs  in  those  secretions  during 
inflammation.  It  is  found  in  the  urine  and  feces  only  under  certain 
diseased  states  of  the  system. 

The  cause  of  the  coagulation  of  albumen  by  heat  has  not  yet  been 
discovered. 

Albumen  has  never  been  obtained  sufficiently  pure  to  admit  of  its 
composition  being  expressed  by  a trustworthy  formula ; Gerhardt 
regarded  it  as  a sodium  compound  (HNaC72HiioNigS022,H20}. 


Fibrin,  Casein,  Legumin. 

Fibrin  is  the  chief  constituent  of  the  muscular  tissue  of  animals. 
It  occurs  in  solution  in  the  blood ; and  its  spontaneous  solidification 
or  coagulation  is  the  cause  of  the  clotting  of  blood  shortly  after  being 
drawn  from  the  body — a phenomenon  which  cannot  at  present  be 
explained  satisfactorily.  Fibrin  may  be  obtained  by  whip])ing  fresh 
blood  with  a bundle  of  twigs,  separating  the  adherent  fibres,  and 
washing  in  water  till  colorless. 


^ s 


Average  Composition  of  Blood  (in  1000  parts). 
(Compiled  by  Kirkes.) 

Water 

Albumen 

Fibrin 

Bed  Corpuscles  : Globulin 

Haematin 

' Cholesterin '^O.OS  ' 

Cerebrin 0.40 

Serolin  0.02 

Oleic  and  margaric  acids 

Volatile  and  odorous  fatty  acid  . . . 

Fat  containing  Phosphorus 


784 

70 

2.2 

123.5 

7.5 


1.3 


CASEIN. 


39t 


Chloride  of  sodium 

Chloride  of  potassium 

g ^ Phosphate  of  sodium  (Na.^POJ 

Carbonate  of  sodium 

Sulphate  of  sodium 

Phosphates  of  calcium  and  magnesium  . . . 

Oxide  and  phosphate  of  iron 

Extractive  matters,  biliary-coloring-matter,  gases,  and 
accidental  substances  . , 


3.6 

.36 

.2 

.84 

.28 

.25 

.50 


5.47 


1000. 

Percentage  proportion  of  the  chief  constituents  of  Blood. 


Water 78.4 

Red  corpuscles 13.1 

Albumen  of  serum 7.0 

Inorganic  salts .603 

Extractive,  fatty,  and  other  matters  . . . .677 

Fibrin 22 


100. 

Casein  occurs  in  Cow’s  Milk  (Lac,  B.  P.)  to  the  extent  of  3 per 
cent.,  dissolved  by  a trace  of  alkaline  salt.  Its  solution  does  not 
spontaneously  coagulate  like  that  of  fibrin,  nor  by  heat  like  albumen  ; 
but  acids  cause  its  precipitation  from  milk  in  the  form  of  a curd 
(cheese)  containing  the  fat  (butter)-globules  previously  suspended  in 
the  milk,  a clear  yellow  liquid  (or  whey)  remaining.  Curds  and 
whey  are  also  produced  on  adding  to  milk  a piece,  or  an  infusion,  of 
rennet,  the  salted  and  dried  inner  membrane  of  the  fourth  stomach 
of  the  calf.  The  exact  action  of  rennet  is  not  known. 


Average  composition  of  1000  parts  of  Millc. 


Solid 

Casein 

Specific 

gravity. 

W ater. 

consti- 

tuents. 

and  ex- 
tractive. 

Sugar. 

Butter. 

Salts. 

Woman  . . . 

1.033 

889 

Ill 

40 

44 

27 

2 

Cow 

1.034 

864 

136 

55 

38 

36 

7 

Specific  gravity  alone,  as  taken  by  the  form  of  hydrometer  termed 
a lactometer,  or  even  by  more  delicate  means,  is  of  little  value  as  an 
indication  of  the  richness  of  milk,  the  butter  and  the  other  solids 
exerting  an  influence  in  opposite  directions.  Good  cow’s  milk  affords 
from  11  to  13  per  cent,  by  volume  of  cream,  and  3 to  3^  per  cent,  of 
butter.  The  water  of  milk  seldom  or  never  varies  more  than  from 
86^  to  87|^  per  cent.,  and  the  solid  constituents  from  13^  to  124. 
Town  milk  is  commonly  3 and  sometimes  2 parts  milk  and  1 part 
water.  Under  the  microscope  milk  is  seen  to  consist  of  minute  cor- 
34 


398 


ALBUMENOID  SUBSTANCES. 


puscles  floating  in  a transparent  medium.  These  corpuscles  consist 
of  fatty  matter  (butter)  contained  in  a filmy  albumenoid  envelope. 

Legumin  or  vegetable  casein  is  found  in  most  leguminous  seeds, 
such  as  sweet  and  bitter  almonds.  Peas  contain  about  25  per  cent, 
of  legumin. 

Vegetable  albumen  is  contained  in  many  plant-juices,  and  is  depo- 
sited in  flocculi  on  heating  such  liquids.  Vegetable  fibrin  is  the 
name  given  by  Liebig  and  Dumas  to  that  portion  of  the  gluten  of 
wheat  which  is  insoluble  in  alcohol  and  ether  [vide  p.  356). 

Albumenoid  substances  are  nearly  identical  in  percentage  compo- 
sition. Albumen  (and  fibrin)  contains  53.5  of  carbon,  7 of  hydrogen, 
15.5  of  nitrogen,  22  of  oxygen,  1.6  of  sulphur,  and  .4  of  phosphorus. 
Casein  contains  no  phosphorus.  These  three  bodies  are  often  termed 
the  plastic  elements  of  nutrition,  under  the  assumption  that  animals 
directly  assimilate  them  in  forming  muscles,  nerves,  and  other  tissues, 
— starch,  sugar,  and  similar  matter  forming  the  resp^Va^ort/ materials 
of  food,  because  more  immediately  concerned  in  keeping  up  the 
temperature  of  the  body  by  the  combustion  going  on  between  them, 
and  their  products,  and  the  oxygen  of  the  air  in  the  blood. 

Musk  (i^osc/l^fc5,  B.  P.  and  U.  S.  P.),  “the  inspissated  and  dried 
secretion  from  the  preputial  follicles  of  Mosclius  moschiferus''  (the 
Musk-Deer),  is  a mixture  of  albumenoid,  fatty,  and  other  animal 
matters  with  a volatile  odorous  substance  of  unknown  composition. 


GELATIGENOUS  SUBSTANCES. 

This  group  of  nitrogenous  bodies  differs  from  true  albumenoid  in 
containing  less  carbon  and  sulphur  and  more  nitrogen.  They  are 
contained  in  certain  animal  tissues,  and  on  boiling  with  water  yield 
a solution  which  has  the  remarkable  property  of  solidifying  to  a 
jelly  on  cooling.  The  tendons,  ligaments,  bones,  skin,  and  serous 
membranes  afford  gelatine  proper ; the  cartilages  give  chondrine, 
which  differs  from  gelatine  in  composition  and  in  being  precipitated 
by  vegetable  acids,  alum,  and  the  acetates  of  lead.  The  purest 
variety  of  gelatine  isinglass,  B.  P.  (Icthyocolla,  U.  S.  P.),  “the 
swimming-bladder  or  sound  of  various  species  of  Acipenser,  Linn., 
prepared  and  cut  in  fine  shreds.’^  h>mall  quantities  are  more  easily 
disintegrated  by  a file  than  a knife.  Fifty  grains  dissolved  in  5 ounces 
of  distilled  water  forms  the  official  “ Solution  of  Gelatine,”  B.  P.  i 
Glue  is  an  impure  variety  of  gelatine,  made  from  the  trimmings  of 
hides ; size  is  glue  of  inferior  tenacity,  prepared  from  the  parings  of  , 
parchment  and  thin  skins.  “ Among  the  varieties  of  gelatine  derived  ^ 
from  different  tissues  and  from  the  same  sources  at  different  ages,  i 
much  diversity  exists  as  to  the  firmness  and  other  characters  of  the  , 
solid  formed  on  the  cooling  of  the  solutions.  The  differences  between  ' 
isinglass,  size,  and  glue,  in  these  respects,  are  familiarly  known,  and  . 
afford  good  examples  of  the  varieties  called  weak  and  strong,  or  low  : 
and  high,  gelatines.  The  differences  are  sometimes  ascribed  to  the  i 
quantities  of  water  combined  in  eu.ch  case  with  the  j)ure  or  anhy-  i 


PEPSINE. 


399 


drous  gelatine,  part  of  which  water  seems  to  be  chemically  combined 
with  the  gelatine ; for  no  artificial  addition  of  water  to  glue  would 
give  it  the  character  of  size,  nor  would  any  abstraction  of  water  from 
isinglass  or  size  convert  it  into  the  hard  dry  substance  of  glue.  But 
such  a change  is  effected  in  the  gradual  process  of  nutrition  of  the 
tissues ; for,  as  a general  rule,  the  tissues  of  an  old  animal  yield  a 
much  firmer  or  stronger  jelly  than  the  corresponding  parts  of  a young 
animal  of  the  same  species.”  (Kirke’s  Physiology.)  Gelatine  ap- 
pears to  unite  chemically  with  a portion  of  the  water  in  which  it  is 
^soaked  when  used  for  culinary  and  manufacturing  purposes,  for  a 
solution  of  glue  in  hot  anhydrous  glycerine  does  not  yield  an  ordinary 
jelly  on  cooling. 


PEPSINE. 

Pepsine  (from  pe'ptd,  to  digest)  is  a nitrogenous  substance 

existing  in  the  gastric  juice,  and  as  a viscid  matter  in  the  peptic 
glands  and  on  the  walls  of  the  stomachs  of  animals.  The  mucous 
membrane  of  the  stomach  (of  the  hog,  sheep,  or  calf,  killed  fasting) 
is  scraped,  and  macerated  in  cold  water  for  twelve  hours ; the  pep- 
sine in  the  strained  liquid  is  then  precipitated  by  acetate  of  lead, 
the  deposit  washed  once  or  twice  by  decantation,  sulphuretted  hydro- 
gen passed  through  the  mixture  of  the  deposit  with  a little  water  to 
remove  the  whole  of  the  lead,  and  the  filtered  liquid  evaporated  to 
dryness  at  a temperature  not  exceeding  105^  F.  Pepsine  is  a power- 
fill  promoter  of  digestion ; its  solution  is  hence  frequently  termed 
artificial  gastric  juice.  As  met  with  in  pharmacy  its  strength 
varies  greatly.  It  is  often  prepared  by  simply  mixing  with  starch 
the  thick  liquid  obtained  on  macerating  the  scraped  stomach  with 
w^ater,  and  evaporating  to  dryness.  ( Vide  Pharmaceutical  Journal. 
1865-66,  p.  112,  and  1871-72,  pp.  785  and  843.) 


QUESTIONS  AND  EXERCISES. 

808.  In  what  form  is  albumen  familiar  ? 

809.  Name  the  chief  test  for  albumen. 

810.  Why  is  the  administration  of  albumen  useful  in  cases  of 
poisoning  ? 

811.  Mention  the  points  of  difference  between  yolk  and  white  of 

egg. 

812.  From  what  sources  other  than  egg  may  albumen  be  obtained? 

813.  In  what  respects  does  fibrin  differ  from  albumen  ? 

814.  Enumerate  the  chief  constituents  of  blood. 

815.  How  may  fibrin  be  obtained  from  blood  ? 

816.  State  the  difference  between  casein,  fibrin,  and  albumen. 

817.  AVhat  are  the  relations  of  cream,  butter,  curds  and  whey,  and 
cheese,  to  milk  ? 


400 


PATTY  BODIES. 


818.  Describe  the  microscopic  appearances  of  blood  and  of  milk. 
819  IIow  much  cream  should  be  obtained  from  good  milk  ? 

820.  What  is  the  percentage  of  .water  in  genuine  milk  ? 

821.  Name  sources  of  vegetable  casein  and  vegetable  albumen. 

822.  Give  the  percentage  of  nitrogen  in  albumenoid  substances. 

823.  Describe  the  chemical  nature  of  musk. 

824.  In  what  lie  the  peculiarities  of  gelatine  ? 

825.  To  what  extent  do  isinglass,  glue,  and  size  differ  ? 

826.  Whence  is  pepsine  obtained  ? 

827.  How  is  pepsine  prepared  ? 


FATTY  BODIES. 

SOAPS,  SOLID  FATS,  FIXED  OILS,  VOLATILE  OILS,  CAMPHORS. 

General  relations. — Oils  and  fats  are,  apparently,  almost  as  sim- 
ple in  constitution  as  ordinary  inorganic  salts.  Just  as  acetate  of 
potassium  (KC2H3O2)  is  regarded  as  a compound  of  potassium  (K) 
with  the  characteristic  elements  of  all  acetates  (C2H3O2),  so  soft 
soap  is  considered  to  be  a compound  of  potassium  (K)  with  the  ele- 
ments characteristic  of  all  oleates  (CigH3302),  and  hence  is  chemically 
termed  oleate  of  potassium  (KC18H33O2).  Olive  oil,  from  which  soap 
is  commonly  prepared,  is  mainly  oleate  of  the  trivalent  radical  gly- 
ceryl (C3H5),  the  formula  of  pure  fluid  oil  being  C3H.3G18H33O2,  and 
its  name  oleine.  The  formation  of  a soap,  therefore,  on  bringing 
together  oil  and  a moist  oxide  or  hydrate,  is  a simple  case  of  double 
decomposition,  as  seen  already  in  connection  with  lead  plaster  (p. 
188),  or  in  the  following  equation  relating  to  the  formation  of  common 
hard  soap  : — i 

SNaHO  4-  C3H,3C,8H3302  = 3NaC,8H3302  + C3H53HO  I 

Hydrate  of  sodium  Oieate  of  glyceryl  Oleate  of  sodium  Hydrate  of  glyceryl  i 

(caustic  soda)  (vegetable  oil).  (hard  soap).  (glycerine). 

Berthelot  has  succeeded  in  preparing  oil  artificially  from  oleic  acid 
and  glycerine ; and  it  is  said  to  be  identical  with  the  pure  oleine  of  , 
olive  and  of  other  fixed  oils.  Hard  fats  chiefly  consist  of  stearine — thiit  | 
is,  of  tristearate  of  glyceryl  (C3H53C]8H3302).  Mr.  Wilson,  of  Price’s  | 
Candle  Company,  obtains  stearic  and  oleic  acids  and  glycerine  by  j 
simply  passing  steam,  heated  to  500^  or  600^  F.,  through  melted  fat.  ' 
Both  the  glycerine  and  fat  acids  distil  over  in  the  current  of  steam,  i 
the  glycerine  dissolving  in  the  condensed  water,  the  fat-acids  floating  1 
on  the  aqueous  liquid. 

The  author  finds  that  oleic  acid  readily  combines  with  alka- 
loids  and  most  of  the  metallic  oxides  or  hydrates,  forming  oleates  » 
which  are  soluble  in  fats.  In  this  way  active  medicines  may  be  ! 
administered  internally  in  conjunction  with  oils,  or  externally  in  , 
the  form  of  ointments. 

Soaps. — Olive  oil  boiled  with  solution  of  potash  yields 
potassium  soap,  or  soft  soap  {Sapo  Mollis^  B.  P.) ; with! 
soda,  sodium  soap,  or  hard  soap  {Sapo  Durns^  B.  P.  and  U.  ^ 


SOAPS 


401 


S.  P.) ; mixed  with  ammonia,  an  ammonium  soap  {Lini- 
mentum  Ammoniae^  B.  P.  and  U.  S.  P.)  ; and  with  lime- 
water,  calcium  soap  {Linimentum  Calcis^  B.  P.  and — flax- 
seed oil — U.  S.  P.), — all  oleates,  chiefly  of  the  respective 
basylous  radicals.  Their  mode  of  formation  is  indicated  in 
the  foregoing  equation.  The  alkali  soaps  are  soluble  in 
alcohol,  the  others  insoluble.  The  official  characters  of 
Hard  Soap  are  : “ grayish-white,  dry,  inodorous  ; horny  and 
pulverizable  when  kept  in  dry  warm  air  ; easily  moulded 
when  heated ; soluble  in  rectified  spirit ; not  imparting  an 
oily  stain  to  paper ; incinerated  it  jdelds  an  ash  which  does 
not  deliquesce.’^  And  of  Soft  Soap:  “yellowish-green, 
inodorous,  of  a gelatinous  consistence ; soluble  in  rectified 
spirit;  not  imparting  an  oily  stain  to  paper:  incinerated 
it  yields  an  ash  which  is  very  deliquescent.” 

The  hard  soap  met  with  in  trade  is  made  from  all  varieties  of 
oil,  the  commoner  kinds  being  simply  the  product  of  the  evapo- 
rated mixture  of  oil  and  alkali ; while  the  better  sorts  have  been 
separated  from  alkaline  impurities  and  the  glycerine  by  the  addi- 
tion of  common  salt  to  the  liquors,  which  causes  the  precipitation  of 
the  pure  soap  as  a curd.  Potash  soap  is  not  precipitable  by  salt. 

Bile,  the  gall  of  the  ox  [Bos  taurus,  Linn.),  freed  from  mucus  by 
agitating  with  twice  its  bulk  of  rectified  spirit  (in  vrhich  mucus  is 
insoluble),  filtering,  and  evaporating,  yields  the  official  Purified  Ox- 
Bile  [Fel  Bovinum  Purificatum,  B.  P.) : the  latter  has  a resinous 
appearance,  but  is  chiefiy  composed  of  two  crystalline  substances 
having  the  constitution  of  a soap ; the  one  is  glycocliolate,  or  simply 
cliolate,  of  sodium  (Na026H4.^N0g),  the  other  is  termed  tauro- 
cholate  of  sodium  (NaC26H^4N07S).  Both  taurocholates  and  gly- 
cocholates  are  conjugated  bodies  readily  yielding,  the  former  cho- 
lalic  acid  (H2C14H39O5)  and  taurine  (C2H7NO3S),  the  latter  cholalic 
acid  and  glycocine  or  glycocoll  (O2H.NO2),  a body  having  interest- 
ing  physiological  relations,  inasmuch  as  it  is  obtainable  from  gelatine 
(hence  the  name  glycocoll,  from  y%vxv^,  glucus,  sweet,  and 
holla,  glue)  and  hippuric  acid.  The  presence  of  bile  in  a liquid  such 
as  urine,  is  detected  by  Pettenkofer’s  test.  The  fluid  is  gradually 
mixed  with  half  its  bulk  of  strong  sulphuric  acid  in  a test-tube,  rise 
of  temperature  being  prevented  by  partial  immersion  of  the  tube  in 
water.  A small  quantity  of  powdered  white  sugar  is  then  introduced 
and  well  mixed  with  the  acid  liquid,  and  more  sulphuric  acid  then 
poured  in ; as  the  temperature  rises  a reddish  or  violet  coloration  is 
produced.  The  cholalic  acid  liberated  in  the  reaction  furnishes  the 
color. 

Solid  Fats. — 1.  Lard  [Adejys  Prceparatus,  B.  P.  and  U.  S.  P.) 
is  the  purified  internal  fat  of  the  abdomen  of  the  hog — the  perfectly 
fresh  omentum  or  flare,  washed,  melted,  strained,  and  dried.  2. 
Benzoated  Lard  [Adeps  Benzoatus,  B.  P.)  is  prepared  lard  heated 
over  a water-bath  with  benzoin  (10  grains  per  ounce),  which  commu- 
nicates an  agreeable  odor  and  prevents  or  retards  rancidity.  Purified 


402 


FATTY  BODIES. 


lard  is  a mixture  of  oleine  and  stearine  ; margarine,  the  margarate  of 
glyceryl,  was  formerly  supposed  to  be  a constituent  of  lard  and  other 
soft  fats,  but  is  now  regarded  as  a mere  mixture  of  palmitine  (the 
chief  fat  of  palm  oil)  and  stearine.  3.  Yellow  Wax  ( Cera  Flava, 

B.  P.  and  U.  S.  P.),  the  prepared  honeycomb  of  the  Hive-Bee,  and 
the  same  bleached  by  exposure  to  sunlight.  4.  White  Wax  ( Cera 
Alba,  B.  P.  and  U.  S.  P.),  according  to  Brodie,  is  chiefly  a mixture  of 
Cerotic  Acid  (HO27H53O.J,  Palmitate  of  Melissyl  (C3oH6i^]6H3i02), 
and  about  5 per  cent,  of  Ceroleine,  the  body  to  which  the  color,  odor, 
and  tenacity  of  wax  are  due.  5.  Spermaceti  ( Cetacenm,  B.  P.  and  U. 

S.  P.)  is  W^palmitate  of  cetyl  (Ci6H330^gH3^02),  or  cetine;  when  sapo- 
nified it  yields  not  glycerine,  the  hydrate  of  glyceryl  (CgH^SHO),  but 
etlial,  the  hydrate  of  cetyl  (CigH33EIO) ; it  is  the  solid  crystalline  fat 
accompanying  sperm  oil  in  the  head  of  the  spermaceti-whale.  6.  Suet, 
the  internal  fat  of  the  abdomen  of  the  sheep,  purified  by  melting  and 
straining,  forms  the  official  Prepared  Suet  (Sevum  Prceparatum, 

B.  P.  and  XJ.  S.  P.) ; it  is  almost  exclusively  composed  of  stearin 
(C3H53Cj8H3g02).  7.  Expressed  oil  of  nutmeg  [Oleum  Myristicce 

Expressum,  B.  P.)  is  a mixture  of  a little  volatile  oil  with  much  yel- 
low and  white  fat,  the  latter  a myristate  of  glyceryl  (C3H53C14H27O2). 

8.  Oil  of  tlieobroma,  or  Cacao-butter  ( Oleum  Theobromce,  B.  P.  and 
U.  S.  P.),  is  a solid  product  of  the  ground  seeds  or  cocoa  nibs  of  the 
Tlieobroma  cacao,  which  also  furnish  cocoa  and  chocolate.  9.  Cocoa- 
nut  oil,  a soft  fat  largely  contained  in  the  edible  portion  of  the  nut 
of  Cocos  nucifera,  or  common  cocoa-nut  of  the  shops,  a body  con- 
taining glyceryl  united  with  no  less  than  six  different  univalent  acid- 
ulous radicals,  namely,  the  caproic  (C6Hji02),  caprylic  (C8H15O2), 
rutic  (C16H19O2),  lauric  (C12H23O2),  myristic  (O14H27O2),  and  palmitic 
(CigH3i02) — radicals  which,  like  some  from  common  resin,  when  united 
with  sodium,  form  a soap  differing  from  ordinary  hard  soap  (oleate 
of  sodium)  by  being  tolerably  soluble  in  a solution  of  chloride  of  . 
sodium  ; hence  the  use  of  cocoa-nut  oil  and  resin  in  making  marine 
soap,  a soap  which,  for  the  reason  just  indicated,  readily  yields  a 
lather  in  sea-water.  I 

Fixed  Oils. — Fixed  and  Volatile  oils  are  naturally  distinguished  ^ 
by  their  behavior  when  heated ; they  also  differ  in  chemical  constitu- 
tion, a fixed  oil  being,  apparently,  a combination  of  a basylous  with 
an  acidulous  radical,  while  a volatile  oil  is  commonly  a neutral  hy- 
drocarbon. 

Drying  and  Non-drying  Oils. — Among  fixed  oils,  most  of  which 
are  oleate  with  a little  palmitate  and  stearate  of  glyceryl,  a few,  such 
as,  1,  linseed  [Oleum  Lini,  B.  P.  and  U.  S.  P.,  contained  in  Lini 
Semina,  B.  P.,  Linum,  U.  S.  P.,  or  Flaxseed,  the  ground  residue  of  1 
which,  after  removal  of  some  of  the  oil,  is  linseed  meal,  Lini  Farina,  \ 
U.  S.  P.),  and,  2,  cod-liver  [Oleum  Morrhuce,  B.  P.  and  U.  S.  P.),  j 
and,  to  some  extent,  castor  and  croton,  are  known  as  drying  oils,  j 
from  the  readiness  with  which  they  absorb  oxygen  and  become  hard-  i 
ened  to  a resin.  Linseed  commonly  contains  37  or  38  per  cent,  of  j 
oil ; 25  to  27  per  cent,  is  obtained  by  submitting  the  ground  seeds  to  I 
hydraulic  pressure,  10  or  12  per  cent,  remaining  in  the  residue  oil-  i 
cake.  Among  the  non-drying  oils  arc  the  following:  3,  Almovd  ; 


FIXED  OILS. 


403 


oil,  indifferently  yielded  by  the  bitter  [Amygdala  Amara,  B.  P. 
and  U.  S.  P.)  or  sweet  seed  [Amygdala  Dulcis,  B.  P.  and  U.  S.  P.) ; 
4,  Croton  oil  [Oleum  Crotonis,  B.  P.,  Oleum  Tiglii,  U.  S.  P.), 
which  seems  to  contain  crotonate  of  glyceryl  (C3H5304H502)- 
Geuther,  however,  states  that  no  such  acid  as  crotonic  is  obtainable 
from  croton  oil,  but  acetic,  butyric,  valerianic,  and  higher  members 
of  the  oleic  series,  together  with  tiglic  acid,  5,  Olive 

oil  ( Oleum  Olivoe,  B.  P.  and  U.  S.  P.),  already  noticed ; 6,  Castor 
oil  [Oleum  Ricini,  B.  P.  and  U.  S.  P.),  a ricinoleate  of  glyceryl 
(C3H53C18H33O3)  or  ricinoleine,  a slightly  oxidized  oleine,  soluble, 
unlike  most  fixed  oils,  in  alcohol;  7,  Oil  oi  male  fern  [Filix  Mas, 
B.  P.  and  U.  S.  P.) , a vermifuge  obtained  by  exhausting  the  rhizome 
with  ether  and  removing  the  ether  by  evaporation — a dark-colored  oil 
containing  a little  volatile  oil  and  resin,  and  officially  termed  an  ex- 
tract [Extractum  Filicis  Liquidum,  B.  P.)  ; 8,  Fixed  oil  of  mustard, 
a bland,  inodorous,  yellow  or  amber  oil,  yielding,  by  saponification 
and  action  of  sulphuric  acid,  glycerine,  oleic  acid,  and  erucic  acid, 
HO22H41O2  (Darby) ; 9,  Lycopodium  Oil  from  the  sporules  of  Club- 
moss. 

Their  physical  qualities  and  the  formulae  of  their  acidulous  radicals 
show  that  the  fatty  bodies  are  closely  related,  and  indicate  that  the 
natural  processes  by  which  they  are  formed  are  probably  as  closely 
related.  The  following  Table,  from  Miller’s  “ Elements  of  Chemis- 
try,” well  shows  the  homology  of  the  fat-acids,  and  gives  their  names, 
formulae,  melting-points,  boiling-points,  and  natural  and  artificial 
sources.  For  further  information  respecting  the  more  commonly 
occurring  of  these  acids,  the  reader  is  referred  to  the  Index,  and 
for  others  to  larger  chemical  works,  or  Watts’s  “Dictionary  of 
Chemistry.” 


Acids. 

Formulae. 

Melting  point. 

Boiling  point. 

Whence  obtained. 

Molec.  Vol.  = 2. 

op. 

^C. 

°F. 

°G. 

f Red  ants;  distillati 

Formic 

HC  H O2 

21 

—6 

221 

105.3 

J oxalic  acid  ; and  ( 

[ tion  of  amylaceou 

f other  organic  bodi( 

( Distillation  of  wood; 

Acetic 

HC,  H3O, 

63 

17 

243 

117 

-J  oxidation  of  alco- 
( hoi,  etc. 

Propionic .... 

HCsH^O, 

... 

... 

284 

140 

( Fermentation  of  gly- 
\ cerin,  etc. 
r Butter ; fermenta- 

Butyric 

HC4  H,  0, 

below 

—20 

314 

157 

-j  tion  of  lactic  acid, 

0 

I etc. 

r Valerian-root ; oxi- 

Valerianic... 

HCj  H,  0, 

(( 

u 

347 

175 

\ dation  of  fousel 
f oil. 

Batter. 

Caproic 

HCe  H„0, 

392 

200 

(Enanthylic. 

HC,  H13O, 

u 

a 

298? 

148? 

f Castor  oil  by  distil- 
1 lation,  etc. 

Caprylic 

HC,  H,,0, 

59 

15 

457 

236 

Butter;  cocoa-nut  oil. 

Pelargonic... 

hc,h„o, 

... 

500 

260 

i Leaves  of  the  gera- 
\ nium. 

Rutic 

HCioHjg02 

86 

30 

... 

... 

( Batter;  oil  of  rue  b 
\ dation. 

Laurie 

HC^HggOg 

110 

43 

... 

... 

1 Cocoa-nut  oil ; berries 
( bay  tree. 

Myristic 

HCi,H2,02 

129 

54 

... 

(Nutmeg-butter;  cocc 
\ oil,  etc. 

Palmitic 

HC,eH3,02 

143.6 

62 

... 

... 

j Palm  oil ; butter ; bee 
\ etc. 

Stearic 

HC18H35O2 

159 

70.5 

Most  solid  animal  fat 

Arachidic.... 

HC2(|H3y02 

167 

75 

... 

Butter;  oil  of  grounc 

Cerotic 

HC2,H,302 

174 

79 

Beeswax. 

Melissic 

HCaoH^gO^ 

192 

89 

... 

... 

Beeswax. 

QUESTIONS  AND  EXERCISES. 

828.  Give  a sketch  of  the  general  chemistry  of  fixed  oils,  fats  and 
soaps. 

829.  What  is  the  difference  between  Hard  and  Soft  Soap  ? | 

830.  Which  soaps  are  official  ? J 

831.  Name  the  source  of  lard,  and  state  how  “ Prepared  Lard"  is  i 

obtained.  « 

832.  State  the  composition  of  Beeswax.  | 

833.  In  what  does  Spermaceti  differ  from  other  solid  fats  ? 

834.  ISfention  the  chief  constituent  of  Suet. 

835.  Whence  is  Cacao-Butter  obtained  ? ; 

836.  Why  is  marine  soap  so  called,  and  from  what  fatty  matter  * 

is  it  exclusively  prepared  ? ! 


VOLATILE  OILS. 


405 


837.  What  do  you  understand  by  drying  and  non-drying  oils  ? 

838.  In  what  respect  does  Castor  Oil  differ  from  other  oils? 

839.  How  is  oil  of  male  fern  {Ex.  Fili.cis  Liquidum)  prepared  ? 

840.  Mention  the  sources  and  formulaB  of  the  following  fat-acids : 
formic,  acetic,  propionic,  butyric,  valerianic,  caproic,  oenanthylic, 
caprylic,  pelargonic,  and  rutic. 


Volatile  Oils. — The  Volatile  or  Essential  Oils  exist  in  various 
parts  of  plants  probably  as  mere  combinations  of  carbon  and  hydro- 
gen ; but  such  hydrocarbons  are  prone  to  change  when  in  contact 
with  oxygen  or  moisture  ; hence  these  liquids  as  they  occur  in  phar- 
macy are  usually  mixtures  of  liquid  hydrocarbons  or  elceoptens  with 
oxidized  hydrocarbons,  ’which  are  commonly  solid  or  camphor-like 
bodies  termed  stearoptens.  On  cooling  a volatile  oil,  a stearopten 
(from  gtiap,  stear,  suet)  often  crystallizes  out ; or  on  distilling  an  oil, 
it  remains  in  the  retort,  being  less  volatile  than  an  elaeopten  (from 
tXotcov,  elaion,  oil,  and  oTtroyav,  optornai,  to  see).  Volatile  oils  should 
be  preserved  in  well-closed  bottles. 

The  process  by  which  volatile  oils  are  usually  obtained 
from  herbs,  flowers,  fruits,  or  seeds,  maybe  imitated  on  the 
small  scale  by  placing  the  material  (bruised  cloves  or  cara- 
ways for  instance)  in  a tubulated  retort,  adapting  the  retort 
to  a Liebig’s  condenser,  and  passing  steam,  generated  in  a 
Florence  flask,  through  a glass  tube  to  the  bottom  of  the 
retort.  The  steam  in  its  passage  upward  through  the  sub- 
stance will  carry  the  oil  over  the  neck  of  the  retort  into  the 
condenser,  and  thence,  liquefied  and  cooled,  into  the  receiv- 
ing vessel,  where  the  oil  will  be  found  floating  on  the  water. 
It  may  be  collected  by  running  off  the  distillate  through  a 
glass  funnel  having  a stopcock  in  the  neck,  or  by  letting  the 
water  from  the  condenser  drop  into  an  old  test-tube  which 
has  a small  hole  in  the  bottom,  or  any  similar  tube  placed 
in  a larger  vessel,  the  water  and  oil  being  subsequently  run 
off  separately  from  the  tube  as  from  a pipette.  The  water 
will  in  most  cases  be  the  ordinary  official  medicated  water 
of  the  material  operated  on  (Aqua  Aurantii  Floris^  Anethi^ 
Carui^  Cinnamomi^  Fceniculi^  Mentlise  Piperitse.^  Menthse 
Viridis.^  Pimentse^  Posse — from  Posse  Gentifolise  Petala^  B. 
P.  and  U.  S.  P. — Sambuci).  Volatile  oils,  like  fixed  oils, 
stain  paper,  but  the  stain  of  the  former  is  not  permanent 
like  that  of  the  latter.  Oils  of  lemon  and  orange  are  some- 
times obtained  by  mere  pressure  of  the  rind  of  the  fruit. 

A large  number  of  volatile  oils  are  employed  in  medicine,  either 
in  the  pure  state,  in  the  form  of  saturated  aqueous  solution  (medicated 
waters),  solution  in  spirit  of  wine,  1 in  5 {Essentm  Anisi  and  Essen 
tia  Mentlice  Piperitce,  B.  P.)  and  1 in  50  {Spiritus  Cajuputi,  Juni^ 
peri,  LavandidcCj  Menthce  Piperitce,  Myristicce,  Posmarini),  or 


406 


PATTY  BODIES. 


as  leading*  constituents  in  various  barks,  roots,  leaves,  etc.  The 
strength  of  Spzritus  Amsi,  U.  S.  P. ; Sp.  Cznnamomi,  U.  S.  P. ; 
Sp.  Menthce  Pzperztce,  U.  S.  P.  and  SiJ.  Menth.  Vzrzdzs,  [J.  S.  P.,  is 
1 of  oil  to  15  of  spirit  of  wine.  Perf  umes  (“  scents”  or  “ essences,” 
including  “Lavender-Water”  and  “ Eau  de  Cologne”)  are  for  the 
most  part  solutions  of  essential  oils  in  spirit  of  wine,  or  spirituous 
infusions  of  materials  containing  essential  oils.  The  following  oils 
are,  directly  or  indirectly,  official  in  the  British  Pharmacopoeia. 
1.  Volatile  oil  of  Bitter  Almond  (p.  366).  2.  Oil  of  Dill  [Oleum 

Anethi,  B.  P.),  a pale  yellow,  pungent,  acrid  liquid  distilled  from 
dill-fruit.  It  contains  a hydrocarbon  anethene  (OioHj^.)  and  an 
oxidized  oil  (CioH^^O)  identical  with  the  carvol  of  oil  of  caraway 
(Gladstone).  3.  Oil  of  Aniseed  ( Oleum  Anisi,  B.  P.),  a colorless  or 
pale  yellow  liquid,  of  sweetish  warm  flavor,  distilled  in  Europe  from 
the  Anise-fruit  [Pimpinella  anisum),  and  in  China  from  the  fruit 
of  Star-Anis  [lllicium  anisatum) ; it  is  a mixture  of  a hydrocarbon 
isomeric  with  oil  of  turpentine  and  a stearopten  (CJ0H12O),  which 
crystallizes  out  at  low  temperatures.  4.  Oil  of  Chamomile  ( Oleum 
Anthemidis,  B.  P.),  a bluish  or,  when  old,  yellow  oil,  of  character- 
istic odor  and  taste,  distilled  from  chamomile  flowers  [Anthemidis 
flares,  B.  P.) : the  official  variety  [Anthemis  nohilis)  yields  an  oil 
composed  of  a hydrocarbon  (CioHj^.)  and  an  oxidized  portion 
(CjoHj(,02  or  OjHj^O),  which,  heated  with  potash,  gives  angelate  of 
potassium  (KC5H-O2),  whence  is  obtained  angelic  acid  (HC5H7O2)  ; 
while  the  flowers  of  another  variety  [Matricaria  Chamomilla,  U.  S. 
P.)  contain  a stearopten  (CioH^pO)  having  the  composition  of  laurel- 
camphor.  5.  Oil  of  Horseradish-root  [Armoracice  Radix,  B.  P.) 
is,  according  to  Hofmann,  the  sulphocyanate  of  butyl  or  tetryl 
(C^HyCNS);  it  is  the  chief  ingredient  of  Spiritus  Armoracice 
Compositus,  B.  P.  6.  Oil  of  Sweet-Orange  Peel  [Aurantii  Dulcis 
Cortex,  U.  S.  P.)  and  Oil  of  Bitter-Orange  rind  [Aurantii  Amari 
Cortex,  B.  P.  and  U.  S.  P.),  the  flavoring  constituent  of  the  official 
syrup  of  the  peel  [Syrupus  Aurantii,  B.  P.),  and  the  oils  of,  7,  lemon 
[Oleum  Limonis,  B.  P.  and  U.  S.  P.),  from  Lemon  Peel  [Limonis 
Coz'tex,  U.  S.  P.) ; 8,  lime;  9,  bergamot  ( Oleum  Bergamii,  U.  S.  P.) ; 
10,  citron  and  a variety  of  citron  termed  cedm,  resemble  each  other 
in  composition,  containing  hespez'idine,  a hydrocarbon  and 

a small  quantity  of  oxidized  hydrocarbons  OisHjoOg,  and 

(Wright  and  Piesse)  C20H30O3).  11.  Oil  of  Neroli  or  Orange- 
Flower^  the  aqueous  solution  of  which  is  official  in  the  forms  of 
water  [Aqua  Aurantii  Floris,  B.  P.  and  U.  S.  P.)  and  syrup 
[Syrupus  Aurantii  Floris,  B.  P.  and  U.  S.  P.),  contains  a fragrant 
hydrocarbon  (CioHjg),  colorless  when  fresh,  but  becoming  red  on 
exposure  to  light,  and  an  inodorous  oxidized  hydrocarbon.  12.  Oil 
of  Buchu-leaves  [Bucliu  Folia,  B.  P.  and  U.  S.  P.)  consists  of  a 
hydrocarbon  holding  in  solution  a crystalline  stearopten.  13.  Oil 
of  Cardamoms,  from  the  seeds  of  the  capsules  ( Cardamomum,  B.  P. 
and  U.  S.  P.),  is  chiefly  a hydrocarbon  (Cjglljg)  isomeric  with  oil  of 
turpentine.  14.  Oil  of  Cajuput  ( Oleum  Cajuputi,  B.  P.  and  U.  S.  P.) 
is  a mobile  bluish  liquid  the  composition  of  which  (C,oHigO)  seems 
to  be  that  of  the  common  hydrocarbon  associated  with  the  elements 
of  water.  The  green  coloring  matter  of  most  samples  of  cajuput  oil 


VOLATILE  OILS. 


407 


is  organic.  Guibourt,  and,  more  recently,  Histed,  have  found  copper 
in  many  specimens  of  cajuput  oil.  15.  Oil  of  Cara^vay4vmi  ( Carum, 
U.  S.  P.)  [Oleum  Carui,  B.  P.,  Oleum  Cart,  U.  S.  P.)  is  a mixture  of 
carvene  and  carvol  (CjoHj^O).  16.  Oil  of  Cloves  [Oleum  Ca- 

ry ophylli,  B.  P.  and  U.  S.  P.)  and  of  Pimento  [ Oleum  Pimentae,  B.  P. 
and  U.  S.  P.),  both  heavier  than  water,  contain  a liquid  hydrocarbon 
(O.oH.e),  eugenic  acid  a solid  body,  eugenin,  isomeric 

with  eugenic  acid,  and  a second  crystalline  substance,  caryophyllin 
(CioHjgO),  isomeric  with  common  camphor.  17.  Oil  of  Cascarilla- 
bark  [Cascarillce  Cortex,  B.  P.  and  U.  S.  P.)  has  not  been  fully  ex- 
amined. 18.  Oil  of  Cinnamon-'hi\,Y\i  [ Cinnamomi  Cortex,  B.  P.  and 
U.  S.  P.)  and  of  Gassm-bark  is  mostly  hydride  of  cinnamyl  (CgH^OH). 
Boiled  with  nitric  acid  it  furnishes  hydride  of  benzoyl  (C7H5OH)  and 
benzoic  acid  (HO7H5O2).  with  chloride  of  lime  yields  benzoate  of  cal- 
cium(Ca2C7H502),  and  with  caustic  potash  gives  cinnamate  of  potas- 
sium (KC9H-O2).  The  specific  gravity  of  oil  of  cinnamon  ( Oleum 
Cinnamomi,  B.  P.  and  U.  S.  P.)  varies  from  1.025  to  1.050.  19. 

Oil  of  Citronella  is  chiefiy  composed  of  citronellol  (OjoHigO),  proba- 
bly isomeric  with  the  ahsintliol  of  wormwood  (Gladstone).  20.  Oil 
of  Copavia  [Oleum  Copaibce,  B.  P.  and  U.  S.  P.)  and,  21,  of  Cubebs 
[Oleum  Cubebce,  B.  P.  and  U.  S.  P.)  are  hydrocarbons  having  the 
formula  C15H24.  22.  Oil  of  Coriander  [ Coriandri  fructrus,  B.  P., 

Coriandrum,  U.  S.  P.,  Oleum  Coriandri,  B.  P.)  seems  to  have  the 
composition  of  hydrous  oil  of  turpentine  (CjgH^gH20).  23.  Euca- 
lyptus globulus  furnishes  an  oil  the  more  volatile  and  chief  portion 
of  which  is  eucalyptol  (C12H20O).  24.  Oil  oi  Juniper  [Oleum  Juni- 

peri,  B.  P.  and  U.  S.  P.),  the  active  constituent  of  Juniper  Tops  and 
Berries  [Jimiperus,  U.  S.  P.),  is  a hydrocarbon  (CigHjg)  which  by 
contact  with  water  yields  a wdiite  crystalline  hydrous  compound 
(CioHjgH20).  25.  Oil  of  Eennel-iruit  [Oleum  Foeniculi,  U.  S.  P.) 
[Foeniculi  Fructus,  B.  P.  and  U.  S.  P.)  differs  in  odor,  but  contains 
the  same  proximate  constituents  as  oil  of  anise.  26.  Oil  of  Lavender 
[Oleum  Lavandulae,  B.  P.  and  U.  S.  P.)  contains  a hydrocarbon 
which  by  oxidation  yields  common  camphor.  27.  Oil  or  Butter  of 
Orris  [Iris  Florentina)  is  a soft  camphor  (08H^g02),  lighter  than 
water.  28.  Oil  of  Peppermint  [Oleum  Menthae  Piperitce,  B.  P.  and 
U.  S.  P.)  consists  of  a hydrocarbon,  mentliene  (OjgHjg),  which  differs 
from  that  of  most  volatile  oils,  and  hydrous  menthene  (CioH^8H20),  a 
crystalline  stearopten.  29.  Oil  of  Spearmint  [Oleum  Menthae  Viri- 
dis,  B.  P.  and  U.  S.  P.)  contains  a liquid  expressed  by  the  formula 
C10H20O ; also,  according  to  Gladstone,  menthol  (C10H44O)  isomeric 
with  carvol.  30.  Oil  of  Nutmeg  [ Oleum  Myristicae,  B.  P.  and  U. 
S.  P.)  and  of  the  arillus  of  the  nutmeg  or  mace  [Mads,  U.  S.  P.) 
is  composed  of  a hydrocarbon  myristicene  (OjgHig),  and  myris- 
ticol  (OigHj^O) — Gladstone.  30a.  Oil  of  Origanum  [Oleum  or igani, 
U.  S.  P.)  from  Origanum  vulgare,  U.  S.  P.,  is  of  a bright-yellow 
color,  having  an  odor  somewhat  like  peppermint ; it  is  a mixture  of 
a liquid  hydrocarbon  and  a camphor  which  is  deposited  after  long 
standing.  31.  Oil  or  Otto  or  Attar  of  Cabbage-rose  petals  [Rosae 
Centifoliae  Petals,  B.  P.  and  U.  S.  P.,  Oleum  Rosae,  U.  S.  P.)  gives 
the  fragrance  to  Bose  water  [Aqua  Rosae,  B P.).  It  resembles  most 


408 


FATTY  BODIES. 


other  volatile  oils  in  being  composed  of  a hydrocarbon  and  an  oxi- 
dized portion,  but  differs  from  all  in  this  respect,  that  the  hydro- 
carbon is  solid  and  is  destitute  of  odor,  while  the  oxygenated 
constituent  is  liquid  and  the  source  of  the  perfume.  According  to 
Fluckiger  the  solid  hydrocarbon  (CgH^g)  yields  succinic  acid  as  the 
chief  product  of  its  oxidation  by  nitric  acid,  and  in  other  respects 
affords  evidence  of  belonging  to  the  paraffin  series  of  fats.  32.  Oil 
of  Rosemary-tops  [Oleum  Rosmarini,  B.  P.  and  U.  S.  P.)  is  a 
mixture  of  hydrocarbon,  oxygenized  oil,  and  stearopten  in  variable 
proportions.  33.  Oil  of  Rue  [Oleum  Rutce,  B.  P.  and  U.  S.  P.) 
contains  a small  quantity  of  hydrocarbon  (CjgH^g)  with  some 
rutic  aldehyd  (CioH2o^)>  according  to  Greville  Williams  is 
chiefly  euodic  aldehyd  (O11H22O),  some  lauric  aldehyd  (Ci^Hj^O)  also 
being  present.  Gorup-Besanez  and  Grimm  have  obtained  oil  of  rue 
(C11H22O)  artificially  as  one  of  the  products  of  the  destructive  dis- 
tillation of  acetate  and  caprate  of  calcium.  34.  Oil  of  Savin  [Oleum 
Sdbince^  B.  P.  and  U.  S.  P.)  is  isomeric  with  oil  of  turpentine 
CioHig).  35.  Oil  of  Elder-flowers  [Sam, bud  Flores,  B.  P.  and  U.  S. 
P.)  occurs  in  very  small  quantity ; it  has  a butyraceous  consistence. 

It  contains  a hydrocarbon,  samhucene  (OjgHjg),  and  probably  a cam- 
phor. 36.  Oil  of  Sassafras-root  [Oleum  Sassafras,  U.  S.  P.), 
specific  gravity  1.094  [Sassafras  Radix,  B.  P.  andU.  S.  P.),  yields 
safren  (CjgHjg)  and  large  quantities  of  a stearopten,  sassafrol 
(CioHig02).  37.  Oil  of  Mustard  [Oleum  Sinapis,  B.  P.)  is  the 
sulphocyanate  of  allyl  (p.  393).  If  adulterated  with  alcohol,  its 
specific  gravity  is  below  1.015.  38.  Oil  of  Turpentine  [Oleum  Tere- 
binthinoe,  B.  P.  and  U.  S.  P.).  Turpentine  itself  is  really  an  oleo- 
resin  of  about  the  consistence  of  fresh  honey.  It  flows  naturally  or 
by  incision  from  the  wood  of  most  coniferous  trees,  larch  [Larix, 
Europcea)  yielding  Venice  Turpentine,  Abies  balsamea  furnishing 
Canadian  Turpentine,  Balsam  of  Fir  or  Canada  Balsam  ( Tere- 
bintliina  Canadensis,  B.  P.  and  U.  S.  P.),  Pistachia  terebinthus, 
the  variety  termed  Chian  Turpentine,  and  the  Pinus  palustris, 
Pinus  abies,  and  Pinus  pinaster  affording  American  Turpentine 
( Terebinthus,  U.  S.  P.).  Pinus  maritima  gives  the  French  or  Bor- 
deaux Turpentine.  By  distillation  turpentine  is  separated  into  rosin 
or  resin  (which  remains  in  the  still),  and  essential  oil  of  turpentine, 
often  termed  simply  turpentine,  spirit  of  turpentine,  or  ''turps” 
(which  distils  over).  Mixed  with  alkali  to  saturate  resinous  acids, 
and  redistilled,  oil  of  turpentine  furnishes  rectified  oil  of  turpentine. 
Under  the  influence  of  heat,  chemical  agents,  or  both,  oil  of  turpen- 
tine (CjgHjg)  yields  many  derivatives  of  considerable  chemical  in- 
terest. 39.  Oil  of  Valerian-root  ( Valerianae  Radix,  B.  P.  and 
U.  S.  P.)  [Oleum  Valerianae,  U.  S.  P.)  is  a mixture  of  a hydrocar- 
bon (CigHig)  and  valerol  (CgHjgO).  Yalerol  slowly  oxidizes  to 
valerianic  acid,  known  by  its  smell.  A similar  change  occurs  at 
once  if  the  oil  of  valerian  be  allowed  to  fall,  drop  by  drop,  on  heated 
caustic  potash:  CgHig0-p3KH0-+-Il20  =K2C03+KC5H902-h3n2.  i 
By  the  action  of  sulphuric  acid  on  the  valerianate  of  potassium  thus  I 
produced,  valerianic  acid  is  obtained.  40.  Oil  of  Ginger  [Zingiber,  | 
B.  P.  and  U.  S.  P.)  has  the  composition  of  hydrous  oil  of  turpentine.  | 
41.  Woi'mseed  [Chenopodium,  U.  S.  P.)  contains  a volatile  oil. 


CAMPHORS. 


409 


42.  Oil  of  Thyme  [Oleum  Thymi,  U.  S.  P.)  is  a mixture  of  thymene 
(CjoHjg)  and  thymol  a solid  white  crystalline  body.  Thymol 

is  also  contained  in,  43,  Oil  of  Horsemint  [Monarda,  U.  S.  P.). 

Camphors. — In  addition  to  the  stearoptens  or  camphors  already 
mentioned  as  being  contained  in  or  formed  from  volatile  oils,  there 
is  one  that  is  a common  article,  of  trade.  It  is  obtained  from  the 
wood  of  Cam'phora  officinarum,  or  Camphor-Laurel,  in  Japan 
(termed  in  Europe,  Dutch  camphor,  because  imported  by  the  Dutch) 
and  in  China  (known  as  Formosa  camphor),  by  a rough  process  of 
distillation  with  w'ater,  and  is  resublimed  in  this  country  [Cam- 
phora,  B.  P.  and  U.  S.  P.).  The  formula  of  laurel-camphor  is 
CigHjgO.  The  essential  oil  [Oleum  Camphorce,  U.  S.  P.),  from 
which  doubtless  camphor  is  derived  by  oxidation,  is  easily  obtained 
from  the  wood,  and  is  occasionally  met  with  in  commerce  under  the 
name  of  liquid  camphor  or  camphor  oil;  its  formula  is  C20II32O; 
by  exposure  to  air  it  becomes  oxidized  and  deposits  common  cam- 
phor, C2oH320“hO  = 2CioH^gO.  There  is  another  kind  of  camphor  in 
European  markets  less  common  than  laurel-camphor,  but  highly 
esteemed  by  the  Chinese ; it  is  obtained  from  the  Dryobalanops 
aromatica,  and  denominated  Sumatra  or  Borneo  camphor.  It  differs 
slightly  from  laurel-camphor  in  containing  more  hydrogen,  its  for- 
mula being  CigHjgO.  It  is  accompanied  in  the  tree  by  a volatile  oil 
(CioHjg)  isomeric  with  oil  of  turpentine.  This  oil  hornehne,  is  also 
occasionally  met  with  in  trade  under  the  name  of  liquid  camphor  or 
camphor  oil,  but  differs  from  laurel-camphor  oil  in  not  depositing 
crystals  on  exposure  to  air. 

Camphor  is  soluble  to  a slight  extent  in  water  (40  grains  per 
gallon,  Pooley).  The  official  Camphor- w^ater  [Aqua  Camphorce, 
B.  P.  and  U.  S.  P.),  or  Camphor  mixture,  is  such  a solution. 

Cantharidin  (C5llg02?),  the  active  blistering  principle  of  can- 
tharides  [Cantharides,  B.  P.,  Cantharis,  U.  S.  P.)  and  other  vesi- 
cating insects,  has  most  of  the  properties  of  a camphor  or  stearopten. 
It  slowly  crystallizes,  from  an  alcoholic  tincture  of  the  beetles,  in 
fusible,  volatile,  micaceous  plates.  The  following  process  for  the 
extraction  of  cantharidin  is  by  Fumouze  : Powdered  cantharides  are 
macerated  with  chloroform  for  twenty-four  hours;  and  this  treatment 
is  repeated  twice  with  fresh  quantities  of  solvent,  the  residue  having 
been  well  squeezed  each  time.  The  collected  solutions  are  then 
distilled,  and  the  dark-green  residue  treated  with  bisulphide  of  car- 
bon, which  dissolves  fatty,  resinous,  and  other  matters,  and  precipi- 
tates the  cantharidin.  The  precipitate  is  thrown  on  a filter,  washed 
with  bisulphide  of  carbon,  and  recrystallized  from  chloroform.  The 
same  process,  omitting  the  final  recrystallization,  may  be  used  for 
the  quantitative  estimation  of  cantharidin  in  cantharides.  The  aver- 
age quantity  found  is  from  four  to  five  parts  in  one  thousand.  Can- 
tharidin is  readily  soluble  in  warm  glacial  acetic  acid  (Tichborne) 
and  in  acetic  ether. 

Massing  and  Draggendorf  consider  cantharidin  to  be  an  anhydride 
(OgHgOg),  and  that  with  the  elements  of  water  it  forms  cantharidic 
acid  (Il2C5Hg02).  A cantharidate  of  potassium  has  the  composition 
KHCdllgO.^. 

35 


410 


RESINOID  SUBSTANCES. 


QUESTIONS  AND  EXERCISES. 

841.  How  do  volatile  oils  differ  chemically  from  fixed  oils  ? 

842.  What  are  the  general  chemical  characters  of  volatile  oils  ? 

843.  Describe  the  usual  process  by  which  volatile  oils  are  obtained. 

844.  Mention  the  differences  in  composition  between  the  volatile 
oils  of  Antliemis  nohilis  and  Matricaria  chamomilla, 

845.  Give  the  systematic  name  of  oil  of  horseradish. 

846.  State  the  general  composition  of  the  oil  of  lemon,  lime,  ber-  i 

gamot,  citron,  and  cedra.  j 

847.  Name  the  constituents  of  oil  of  cloves. 

848.  In  what  respect  does  oil  (or  otto)  of  roses  differ  from  other  i 

volatile  oils  ? ! 

849.  To  what  class  of  substances  do  the  constituents  of  oil  of  rue 
belong  ? 

850.  How  does  natural  turpentine  differ  from  the  turpentine  of 
trade  ? 

851.  With  what  object  is  commercial  turpentine  rectified? 

852.  How  is  camphor  oil  related  to  camphor  ? 

>•53.  In  what  respects  do  Borneo  or  Sumatra  camphor  and  cam- 
phor oil  differ  from  the  corresponding  products  of  Japan  and  China  ? 

854.  What  is  the  nature  of  cantharidin  ? 


RESINOID  SUBSTANCES.  | 

RESINS,  OLEO-RESINS,  GUM-RESINS,  BALSAMS.  1 

Resins  occur  in  plants  generally  in  association  with  volatile  oils.  ( 
They  closely  resemble  camphors  or  stearoptens,  but  are  not  volatile,  ( 
and  differ  from  oils  and  fats  mainly  in  being  solid  and  brittle.  Oleo-  I 
resins  are  mixtures  of  a resin  and  a volatile  oil.  Gum-resins  are  i 
mixtures  of  a resin  or  oleo-resins  and  gum.  Balsams  are  commonly 
described  as  resins  or  oleo-resins  which  yield  benzoic  or  cinnaniic 
acid ; but  oleo-resins  containing  neither  of  these  acids  are  often 
termed  balsams,  e.  g.,  balsam  of  copaiva  and  Canada  balsam. 

Resins. — 1.  Resin,  rosin,  or  colophony  [Resina,  B.  P.  and  U.  S.  I 
P.)  is  the  type  of  this  class.  Its  source  is  the  oleo-resin  or  true  tur-  | 
pentine  of  the  conifers,  a body  which  by  distillation  yields  spirit  of  | 
turpentine  and  a residuum  of  rosin.  “ Brown”  and  “ White”  rosin  I 
are  met  with  in  trade.  'Hie  former  is  the  residue  of  American,  the  ! 
latter  of  Bordeaux  turpentine  (from  Pinus  Abies,  etc.,  and  Pinus  ,j 
Maritima)  respectively,  llie  chief  constituents  of  brown  resin  are  i 
pinic  acid  (HC2oH.^0.2)  and  sylvic  acid,  identical  in  composition,  ; 
but  differing  in  properties  [vide  Isomerism),  the  former  being  soluble  j 
and  the  latter  insoluble  in  cold  spirit  of  wine.  White  resin  or  ; 
“ galipot”  is  chiefly  pimaric  acid,  also  isomeric  with  pinic  acid. 
Piiiic  acid  heated  yields  colophonic  or  colopholic  acid.  Among  the  , 
products  of  the  destructive  distillation  of  resin,  Tichborne  has  re-  : 
cently  found  “ colophonic  hydrate'"  (CjoH2203,H20),  a white  inodor-  : 


OLEO-RESINS. 


411 


ous  crystalline  substance,  and  by  depriving  this  of  water  obtained 
white  crystalline  colopliomne  Resin  is  soluble  in  oil  of 

turpentine.  Contact  with  sulphuric  acid  immediately  colors  it 
strongly  red.  It  is  a constituent  of  eight  of  the  fourteen  Plasters 
(Emplastra)  of  the  British  Pharmacopoeia.  2.  Armcm,  the  chief 
acrid  if  not  the  only  active  principle  of  Arnica  {Arnicce  Radix,  B. 
P.,  Arnicce  Flores,  U.  S.  P.),  is  a resin.  3.  Cannahin,  said  to  be 
the  active  principle  of  Indian  Hemp  ( Cannabis  Indica,  B.  P.,  Ex~ 
tractum  Cannabis,  U.  S.  P.),  is  usually  described  as  a resin.  4. 
Capsicum-fruit  contains  resin  (p.  351).  5.  Castorin,  a resinous 

matter,  is  the  name  given  to  the  chief  constituent  of  Castor  ( Cas- 
toreum),  B.  P.  and  U.  S.  P.),  the  dried  preputial  follicles  and  in- 
cluded secretion  of  the  Beaver  ( Castor  Fiber).  6.  Ergotin  is  a very 
active  resinoid  constituent  of  Ergot  [Ergota,  B.  P.  and  U.  S.  P.), 
or  “the  sclerotium  (compact  mycelium  or  spawn)  of  Claviceps  pur- 
purea, produced  within  the  paleae  of  the  common  rye,  Secale  cerealei^ 
7.  Guaiacum-resin  is  a mixture  of  several  substances  (p.  369).  8. 

Jalap-resin  (p.  369).  9.  Kousso  [Cusso,  B.  P.)  is  said  to  owe  its 

anthelmintic  property  to  a neutral  bitter  acrid  resin.  10.  Mastic 
[Mastiche,  B.  P.  and  U.  S.  P.)  is  a resinous  exudation  obtained  by 
incision  from  the  stem  of  the  Mastic  or  Lentisk  tree.  Nine- tenths  of 
Mastic  i^mastichic  acid  (020^81^2)?  ^ resin  soluble  in  alcohol ; the 
remaining  tenth,  masticin  (0.,oH3^0)  a tenacious  elastic  resin.  11. 
Mezereon,  the  dried  bark  [Mezerei  Cortex,  B.  P.  and  U.  S.  P.)  of 
Daphne  mezereum,  Mezereon,  and  Daphne  laureola.  Spurge  Laurel, 
owes  its  acridity  to  a resin.  12.  Pepper  contains  a resin  (p.  353).  13. 
Burgundy  Pitch  [Pix  Burgundica,  B.  P.  and  U.  S.  P.)  is  the 
melted  and  strained  exudation  from  the  stem  of  the  Spruce  Fir, 
Abies  Excelsa.  The  term  Burgundy  is  a misnomer,  the  resin  never 
having  been  collected  at  or  near  Burgundy ; Finland,  and  to  a smaller 
extent  Baden,  and  Austria  being  the  countries  whence  it  is  derived. 
Its  constituents  closely  resemble  those  of  common  Kesin.  It  is  often 
adulterated  and  imitated  by  a mixture  of  resin  with  palm-oil,  water, 
etc.,  from  which  it  may  be  readily  distinguished  by  its  duller  yellow 
color,  highly  aromatic  odor,  greater  solubility  in  alcohol,  and  almost 
complete  solubility  in  twice  its  weight  of  glacial  acetic  acid  (Han- 
bury).  14.  Podophyllum-resin  (p.  351).  15.  Pyrethrin\^\\\^  name 

of  the  acrid  resinous  active  principle  of  Pellitory-root  [Pyrethri 
Radix,  B.  P.).  16.  The  resins  of  Rhubarb  have  already  been 

alluded  to  in  connection  with  Chrysophanic  acid  (p.  300).  17.  Rott- 

lerin  is  the  name  given  by  Anderson  to  a crystalline  resin  from 
Kamala  (Kamala,  B.  P.),  the  minute  glands  that  cover  the  capsules 
of  Rottlera  iinctoria  : to  this,  and,  apparently,  allied  resins,  Kamala 
owes  its  activity  as  an  anthelmintic. 

Oleo-resins. — 1.  Copaiva  {Copaiba,  B.  P.  and  U.  S.  P.)  is  a 
mixture  of  about  40  per  cent,  of  essential  oil  (0^51124),  with  two  or 
more  per  cent,  of  brown  soft  resin,  and  50  or  more  of  a yellow  dark 
resin  termed  Copaivic  acid  (020^30^2)*  Copaiva  heated  with  a fourth 
of  its  weight  of  the  official  carbonate  of  magnesium  yields  a transparent 
fluid,  owing  to  the  formation  of  copaivate  of  magnesium  and  solution 
of  this  soap  in  the  essential  oil.  With  an  equal  weight  of  the  car- 


412 


RESINOID  SUBSTANCES. 


bonate  enongli  soap  is  produced  to  take  up  the  whole  of  the  essential 
oil,  and  form  a mass  capable  of  being  rolled  into  pills.  A much 
smaller  quantity  of  calcined  magnesia,  as  might  be  expected,  effects 
the  same  result ; but  more  time,  often  several  days,  is  required  before 
complete  reaction  is  effected.  Quicklime  has  a similar  effect.  Per- 
haps carbonate  reacts  more  quickly  because  of  its  fine  state  of  divi- 
sion and  admixture  of  hydrate — in  which  case  hydrates  of  calcium 
and  magnesium  may  be  expected  to  act  better  than  the  calcined  pre- 
parations, and  in  much  smaller  quantity  than  carbonate  of  magnesium. 
Copaiva  is  soluble  in  its  own  bulk  of  benzol,  and,  unlike,  2,  Wood- 
oil,  a similar  oleo-resin  from  the  Dipterocarpus  turbinatus,  does  not 
become  gelatinous  when  heated  to  270^  F.  Copaiva,  also,  is  not 
fluorescent.  3.  Elemi  [Elemi,  B.  P.)  is  an  exudation  from  an  un- 
known tree  (probably  Canartum  commune).  It  consists  of  volatile 
oil  with  80  or  more  per  cent,  of  two  resins,  the  one  (C20H32O2)  solu- 
ble in  cold  alcohol,  the  other  (C20H33O)  almost  insoluble.  4.  Wood- 
Tar  [Ptx  Liquida,  B.  P.  and  U.  S.  P.)  is  a mixture  of  several  resi- 
noid  and  oily  bodies  (amongst  others  Creasote,  p.  392)  obtained  by 
destructive  distillation  from  the  wood  of  Pinus  sylvestris  and  other 
pines.  When  heated  it  yields  a terebinthinate  oil  and  a residue  of 
pitch.  5.  Turpentines.  These  oleo-resins  have  been  mentioned  in 
connection  with  oil  of  turpentine,  their  volatile,  and  resin,  their  fixed 
constituent.  6.  Common  Frankincense  ( Thus  Americanum^  B. 
P.)  is  the  concrete  turpentine  of  Pinus  tceda.  7.  Canada  Balsam 
[Terehinthina  Canadensis,  B.  P.)  is  the  turpentine  or  oleo-resin  of 
the  Balm  of  Gilead  Fir  [Abies  bahamea).  8.  Sumbul-root  (Sum- 
but  Radix,  B.  P.)  seems  to  owe  its  stimulating  property  to  two 
oleo-resins,  one  soluble  in  ether,  the  other  in  alcohol.  9.  Oleo-resin 
of  Lupuliii  (U.  S.  P.)  is  an  ethereal  extract  of  the  yellow  powder 
[Lupulina,  U.  S.  P.)  attached  to  the  small  nuts  at  the  base  of  the 
scales  which  form  the  aggregate  fruit  of  the  Hop  [Humidus  Lupu- 
lus).  It  contains  essential  oil  of  hop  and  oxidized  oil  or  resin. 
Oleoresince  Capsid,  CubebcB,  Piperis,  and  Zingiberis  are  also  offi- 
cial in  the  United  States  Pharmacopoeia.  10.  Pix  Canadensis,  U.  | 
S.  P.,  is  the  concrete  juice  of  Abies  Canadensis.  i 

Gum-resins. — 1.  Ammoniacum  [Ammoniacum,  B.  P.  and  U.  S. 
P.)  is  an  exudation  from  the  Dorema  Ammoniacum.  It  contains  | 
nearly  20  per  cent,  of  gum  and  about  70  of  resin  (C^oH^QOy — John-  1 
ston).  2.  Assafotiida  [Assafoetida,  B.  P.)  is  a gum-resin  obtained,  [ 
by  incision,  from  the  living  root  of  Narthex  assafoetida.  It  contains  t 
from  50  to  70  per  cent,  of  resin,  25  to  30  per  cent,  of  gum  (about  two-  \ 
thirds  arabin,  one-third  bassorin,  p.  97),  and  3 to  5 per  cent,  of  vola- 
tile  oil.  3.  Gamboge  [Cambogia,  B.  P.  and  U.  S.  P.)  is  obtained 
from  the  Garcinia  morella.  AVhen  of  best  quality  it  contains  from  1) 
20  to  25  per  cent,  of  gum,  and  80  to  75  per  cent,  of  a resin  termed  jl 
gambogic  acid  (C20H23O4).  4.  Galbanum  [Galbanum,  B.  P.  and  ;! 
U.  S.  P.)  contains  from  20  to  25  per  cent,  of  gum,  and  about  65  per  !• 
cent,  of  resin  (G^yH^^O^),  and  3 or  4 per  cent,  of  volatile  oil.  5.  | 
Myrrh  [Myrrha,  B.  P.  and  U.  S.  P.),  an  exudation  from  the  stem  |i 
of  Balsamodendron  myrrha,  contains  about  half  its  weight  of  solu-  |t 
ble  gum  (probably  arabin),  10  per  cent,  of  insoluble  gum  (probably  |; 


BALSAMS. 


413 


bassorin),  of  volatile  oil,  and  about  25  per  cent,  of  resin  (rayrrhic 
acid).  6.  Scammony  (p.  371). 

Gum-resins  need  only  be  finely  powdered  and  rubbed  in  a mortar 
with  water  to  yield  a medicial  emulsion,  in  which  the  fine  particles 
of  resin  are  held  in  suspension  by  the  aqueous  solution  of  gum. 

Balsams. — 1.  Benzoin  [Benzoinum,  B.  P.  and  U.  S.  P.)  is  ob- 
tained from  incisions  of  the  bark  of  Styrax  benzoin.  It  contains 
12  to  15  per  cent,  of  benzoic  acid  (p.  298),  about  50  per  cent,  of  a 
resin  (a)  soluble  in  ether,  25  to  30  per  cent,  of  a resin  (d)  soluble  in 
alcohol  only,  and  3 to  4 per  cent,  of  a resin  (y)  soluble  in  solution  of 
carbonate  of  sodium.  The  a resin  is  considered  to  be  a compound 
of  the  3 (C^qH^^Oc,)  and  the  y (C30H4QO5).  The  balsams  of  Peru, 
Tolu,  and  Storax  differ  from  benzoin  in  containing  cinnamic  (p.  407) 
in  place  of  benzoic  acid ; hence  they  yield,  by  oxidation,  hydride  of 
benzoyl  (oil  of  bitter  almonds).  2.  Balsam  of  Peru  [Balsamum 
Peruvianum,  B.  P.  and  U.  S.  P.),  from  the  Myroxylon  Pereiras,  is 
a mixture  of  70  per  cent,  of  oily  with  about  23  of  resinous  matter, 
and  6 per  cent,  of  cinnamic  acid.  The  oil,  by  fractional  distillation 
in  an  atmosphere  of  carbonic  acid  gas  and  under  diminished  pres- 
sure, furnishes  benzylic  alcohol  (C-H^HO),  benzoate  of  benzyl 
(C7H-C7H.O.J,  and  cinnamate  of  benzyl  . (Kraut). 

By  action  of  alcoholic  solution  of  potash  it  yields  benzoate  and  cin- 
namate of  potassium,  and  benzylic  alcohol;  also  cinnamic  alcohol 
(C9H9HO),  otherwise  known  as  'peruvine  ov  sty  rone  ; it  also  often 
holds  in  solution  metacirtnamSin  or  styracin  (C,3Hjg02),  isomeric 
with  hydride  of  cinnamyl  (CgH^OH).  The  resin  of  balsam  of  Peru 
seems  to  result  from  the  action  of  moisture  on  the  oil.  The  constitu- 
ents of  Vanilla,  U.  S.  P.,  the  prepared  unripe  pods  of  a plant,  some- 
what resemble  those  of  Balsam  of  Peru.  The  crystals  often  found 
on  vanilla  are  a weak  acid  substance  having  the  formula 
(Carles).  3.  Balsam  of  Tolu  [Balsamum  Tolutanum,  B.  P.  and 
U.  S.  P.)  is  an  exudation  from  incisions  in  the  bark  of  Myroxylon 
toluifera  ; it  closely  resembles  balsam  of  Peru,  but  is  more  suscepti- 
ble of  resinification.  Old  hard  balsam  of  tolu  is  a convenient  source 
of  cinnamic  acid,  which  is  extracted  by  the  same  process  as  that  by 
which  benzoic  acid  is  obtained  from  benzoin,  namely,  ebullition  with 
alkali,  filtration,  and  precipitation  by  hydrochloric  acid.  4.  Storax 
is  an  oleo-resin  obtained  from  the  Liquidambar  orientale.  It  con- 
tains a volatile  oil  term  styrol  (C^Hg),  cinnamic  acid,  styracin,  and 
a soft  and  a hard  resin.  Styrol  differs  from  similar  hydrocarbons  in 
being  converted  into  a polymeric  solid  termed  metastyrol  or  draconyl 
on  the  mere  application  of  a temperature  of  about  400^  F.  For 
medicinal  use,  storax  [Styrax  Prceparatus,  B.  P.  and  U.  S.  P.)  is 
purified  by  solution  in  alcohol,  filtration,  and  removal  of  the  alcohol 
by  distillation. 

Caoutchouc  or  India-rubber,  and  Gutta  Percha. 

Caoutchouc  is  the  hardened  juice  of  Hevea  [Siphonia]  Brazili- 
ensis,  Castilloa  elastica,  Urceola  elastica.  Ficus  elastica,  and  other 
plants  (Collins).  Heated  moderately  with  sulphur  it  takes  up  2 or 
3 per  cent.,  and  forms  vulcanized  India-rubber ; at  a higher  tem- 

35* 


414 


COLORING  - MATTERS. 


perature  a hard  horny  product,  termed  ebonite  or  vulcanite,  results. 
Gutta  Percha  (U.  S.  P.)  is  the  concrete  drop  or  juice  of  the  percba 
(Malay)  tree,  the  Isonandra  gutta,. smd  of  other  Sapotaceous  plants,  j 
It  is  soluble  in  chloroform  (Liquor  Gutta-percha,  U.  S.  P.),  benzoyl, 
and  essential  oils.  White  gutta  percha  is  obtained  by  precipitating 
a solution  of  the  ordinary  gutta  percha  in  chloroform  by  alcohol, 
washing  the  precipitate  with  alcohol,  and  finally  boiling  in  water 
and  moulding  into  desired  form  while  still  hot. 

These  two  elastic  substances,  in  the  pure  state,  are  hydrocarbons 
(xCgH^),  usually  slightly  oxidized. 


QUESTIONS  AND  EXERCISES. 

855.  Distinguish  between  resins  and  camphors.  Mention  the  points 
of  difference  of  resins,  oleo-resins,  gum-resins,  and  balsams. 

856.  Name  the  constituents  of  common  Resin. 

857.  Enumerate  some  official  articles  of  which  the  active  constitu- 
ents are  resins. 

858.  Give  the  chief  distinguishing  characters  of  Burgundy  Pitch. 

859.  What  is  the  average  proportion  of  oil  in  Copaiva  ? 

860.  Explain  the  effect  of  magnesia  or  lime  on  copaiva. 

861.  State  the  nature  of  Wood-tar. 

862.  Why  do  Ammoniacum,  Assafoetida,  Gamboge,  Galbanum, 
and  Myrrh  give  an  emulsion  by  mere  trituration  with  water  ? 

863.  In  what  respect  does  Benzoin  differ  from  the  Balsams  of 
Peru,  Tolu,  and  Storax  ? 

864.  What  is  the  chemical  nature  of  India-rubber  and  Gutta 
Percha  ? 

865.  How  is  India-rubber  vulcanized  and  converted  into  ebonite 
or  vidcanite  ? 


COLORING-MATTERS. 


The  animal,  vegetable,  and  mineral  kingdoms  abound  in  sub-  Ij 
stances  or  pigments  which  powerfully  decompose  light,  absorbing  |j 
certain  of  its  constituent  colors,  and  reflecting  some  others.  Thus,  j] 
for  example,  most  leaves  contain  a body  termed  chlorophyll,  which  j| 
has  the  property  of  absorbing  red  light  and  reflecting  green  ; these  [. 
reflected  rays  entering  the  eye  of  an  observer,  and  striking  on  the  fi 
retina  (the  expanded  extremity  of  the  optic  nerve),  always  commu-  n 
nicate  the  same  impression  to  the  brain  ; in  popular  language  the  n 
leaf  is  said  to  be  green.  Art  has  added  largely  to  the  number  of  ; 
natural  coloring-matters.  , 

Yellow. — I.  Chrome-yellow  occurs  in  more  than  a dozen  shades 
(see  Lead,  chromate  of).  2.  Fustic  or  yellow  wood  is  the  wood  of  '• 
the  Phus  cotinus.  3.  Gamboge  (see  Gamboge).  4.  Ochre  is  met  ! 
with  of  many  tints,  under  the  names  of  yellow  ochre,  gold  yellow,  ’ 
gold  earth  or  ochre,  yellow  sienna,  Chinese  yellow.  It  is  chiefly  ; 


COLORING-MATTERS. 


415 


a mixture  of  oxyhydrates  of  iron  with  alumina  and  lime.  5.  Orpt- 
ment  is  a sulphide  of  arsenicum  ( As.^Sg).  6.  Persian  berries  or  Avig- 
non grains  contain  a principle  termed  chrysorhamnin 
They  are  the  product  of  the  Rliamnus  infectorius.  1.  Purree  or 
Indian  yellow  is  said  by  Stenhouse  to  owe  its  color  to  purrate  or 
euxanthate  of  magnesium  (MgG\2H34022).  8.  Quercitron  is  the 

bark  of  Quercus  tinctoria^  U.  S.  F.,  or  Black  Oak.  It  contains 
the  yellow  glucoside,  quercitrin  (Oj^H,gOio,H20).  9.  Rhubarb  (see 
Chrysophanic  acid,  p.  300).  10  Saffron  [Crocus,  B.  P.  and  U.S. 

P.),  the  dried  stigma  and  part  of  the  style  of  Crocus  sativus,  yields 
saffranin  or  polychroite,  a yellow  principle  whose  chemistry  is  but 
little  known.  11.  Turmeric,  the  rhizome  of  Curcuma  longa,  owes 
its  yellow  color  to  curcumin,  a resinous  matter,  the  formula  of  which 
is  said  by  Daube  to  be  OioHio^s?  and  by  Iwanof  C^H^O.  Possibly 
two  yellow  pigments  are  present.  12.  Weld  [Reseda  luteola)  con- 
tains a durable  yellow  matter  termed  luteolin  13.  Picric 

or  carbazotic  acid  (p.  392)  is  a very  powerful  yellow  dye.  14.  Dried 
and  powdered  carrots  yield  to  bisulphide  of  carbon  a yellow  coloring- 
matter,  “ carrotin,”  which  is  obtained  on  evaporating  the  solvent. 
It  is  said  to  be  used  in  coloring  butter. 

Red. — 1.  Alkanet,  the  root  of  Alkanna  tinctoria,  Tausch,  An- 
cliusa  tinctoria,  yields  anchusin  (C35II40O8),  a resinoid  matter 
soluble  in  oils  and  fats.  2.  Annato,  Arnatto,  or  Arnotto,  a paste 
prepared  from  the  seeds  of  Bixa  orellana,  contains  bixin,  an  orange- 
red,  and  orellin,  a yellow  principle.  3.  Brazil-wood  [ Ccesalpinia 
brasiliensis)  furnishes  brezilin,  the  basis  of  several  lakes.  Sapan- 
wood  and  Cam-ivood  probably  contain  the  same  substance.  4.  Cin- 
nabar, Chinese  red.  Vermilion,  or  Paris  red  is  mercuric  sulphide. 
5.  Chrome-red  is  an  oxychromate  of  lead.  6.  Cochineal  (p.  300). 
7.  Madder,  the  root  of  Rubia  tinctorum,  powdered  and  treated 
with  sulphuric  acid  and  acidulated  water  to  effect  the  removal  of 
earthy  and  other  inert  matters,  furnishes  a residual  powder  termed 
garancin.  Garancin  yields  to  pure  water  alizarin  (Cj^Hj^O^,  3H2O), 
the  red,  neutral,  crystallizable  coloring-matter  of  madder.  Alizarin 
does  not  exist  ready  formed  in  the  plant,  but  is  derived,  by  fermen- 
tation, from  rubian,  a yellowish  resinoid  substance.  Alizarin  is  now 
produced  artificially  from  anthracene,  one  of  the  solid  constituents 
of  coal-tar.  8.  Mulberry-juice  [Mori  Succus,  B.  P.)  contains  a 
violet-red  coloring-matter  which  has  not  been  chemically  examined. 
9.  Red  lead  (p.  187).  10.  Red  oxide  of  iron,  of  shades  varying 

from  light  to  brown  red,  is  found  native.  The  common  names  of  it 
are  Armenian  bole,  Berlin-red,  colcothar,  English  red,  red  ochre, 
burnt  ochre,  red  earth,  terra  di  sienna,  mineral  purple,  stone  red, 
and  Indian  red.  11.  Red  Sandal-wood  [Pterocarpi  Lignum,  B.  P. 
and  U.  S.  P.),  the  billets  and  chips  of  Pterocarpus  santalinus,  owes 
its  color  to  santalin  (CigHjg03),  a resinoid  matter.  12.  Red-Poppy 
Petals  [Rhcedos  Petula,  B.  P.),  from  the  papaver  rhceas,  contain  a 
red  coloring  principle  which  has  not  yet  been  isolated.  13.  Red- 
Rose  Petals  [Rosce  Gallicce  Petala,  B.  P.  and  U.  S.  P.)  also  yield 
a red  substance  which  has  not  been  analyzed.  14.  Safflotver, 
Dyer's  Saffron  or  Bastard  Saffron,  the  florets  of  Carthamus  tine- 


416 


COLORING-MATTERS. 


torius,  contains  an  unimportant  yellow  dye,  and  5 per  cent,  cartha- 
min  an  uncrystallizable  red  dye,  the  pigment  of  the  old 

])ink  saucers.  Carthamin  seems  to  possess  acid  characters,  and  (like 
silicic  acid  and  other  substances)  to  be  soluble  in  water  for  a certain 
time  after  liberation  from  its  alkaline  solution ; for  fabrics  are  dyed 
with  safflower  by  immersion  in  a bath  made  of  an  infusion  in  dilute 
alkali  neutralized  by  citric  acid  immediately  before  use,  the  cartha- 
niin  probably  penetrating  the  cells  and  vessels  of  the  fibres  in  a solu- 
ble form,  there  becoming  insoluble  and  imprisoned  and  thus  giving 
permanent  color  to  the  wool,  silk,  or  other  material.  Mixed  with 
French  chalk,  carthamin  is  used  as  a cosmetic  under  the  name  of 
vegetable  rouge — carmine  being  animal  rouge,  and  red  oxide  of 
iron  mineral  rouge.  15.  Lac-dye  a cheap  form  of  cochineal,  and 
is  also  yielded  by  a species  of  Coccus.  16.  Logwood  [HcBmatoxyli 
Lignum,  B.  P.)  contains  a yellow  substance,  licematoxylin 
OgH.^O  or  SH^O),  which,  under  the  influence  of  air  and  alkali, 
assumes  an  intense  red  color.  17.  Red  enamel  colors,  for  glass- 
staining  and  ceremic  operations,  are  produced  either  by  cuprous  sili- 
cate or  purple  of  Cassius  (p.  218). 

Blue. — 1.  Cobalt  oxide  precipitated  in  combination  or  admixture 
with  alumina  or  phosphate  of  calcium  forms  Thenar d's  blue,  cobalt- 
blue,  Hoffne  fs  blue,  and  cobaltic  ultramarine.  2.  Smalt,  Saxony 
blue,  or  King's  blue,  is  rough  cobalt  glass  in  fine  powder  (p.  207). 

3.  Copper-blue,  mountainMue,  and  English  or  Hambro'  blue  are 
carbonates  or  oxycarbonates  of  copper.  4.  Indigo  (p.  258).  5.  Lit- 
mus, lichen-blue,  turnsole,  orchil  or  archil,  and  cudbear  products 
of  the  action  of  air  and  alkalies  on  certain  colorless  principles,  as 
orcin  (0711^02),  derived  from  different  species  of  lichen — Roccella, 
Variolaria,  and  Lecanora.  6.  Prussian  blue  (p.  303)  and  Turn- 
bidVs  blue  [\).  304),  the  ferro-  and  ferridcyanides  of  iron,  are  met 
with  under  the  names  of  Erlangen,  Louisa,  Saxon,  Paris,  or  Berlin 
blue.  7.  Ultramarine  is  made  on  a large  scale  by  roasting  a mix- 
•ture  of  fine  white  clay,  carbonate  of  sodium,  sulphur,  and  charcoal. 
Its  constitution  is  not  well  made  out.  Acids  decompose  it,  sulphu-  | 
retted  hydrogen  escaping.  j 

Green. — 1.  Cupro-arsenical  green  pigments  (p.  152).  2.  Chlo-  j 

rophyll.  Leaf-green,  or  Chromule.  A method  of  extracting  chlo-  j 
rophyll  is  given  under  “ Extracts,*'  vide  Index.  It  is  resinoid,  soluble  j 
in  alcohol  and  ether,  insoluble  in  water,  and,  according  to  Fremy,  r 
consists  of  a blue  substance,  phyllocyanin  (Og^IIfigN^Oj^  ?),  and  a j 
jeWovf,  phylloxanthin ; the  yellow  tints  in  fading  autumnal  leaves,  | 
he  says,  are  due  to  the  latter  principle,  the  former  being  the  first  to  j 
fade.  3.  Sap-green,  buckthorn-,  vegetable-,  or  bladder-green  is  ob-  j 
tained  by  evaporating  to  dryness  a mixture  of  lime  and  the  juice  j 
[Rliamm  Succus,  B.  P.)  of  the  berries  of  the  Buckthorn  [Rhamnus  j 
catharhcus).  It  is  soluble  in  water,  slightly  in  alcohol,  and  insolu-  1 
ble  in  ether  and  oils.  4.  Green  ultramarine  is  made  by  a process  ! 
similar  to  that  for  blue  ultramarine.  5.  Mixtures  of  blue  and  yellow  ( 
pigments  and  dyes  are  common  sources  of  green  colors.  6.  Glass  ■ 
and  earthenware  are  colored  green  by  oxide  of  chromium  and  black  | 
oxide  of  copper.  1 


COLORING-MATTERS. 


417 


Brown. — 1.  Umber,  Sienna,  or  Chestniit-hrown  is  found  native. 
By  heat  it  is  darkened  in  tint,  and  is  then  known  as  burnt  umber. 
It  is  a mixture  of  oxide  of  iron,  silica,  and  alumina.  2.  Sepia  is  a 
dried  fluid  from  the  ink-bag  of  cuttlefishes  {Sepiadce) ; by  its  ejection 
into  adjacent  water  the  animal  obtains  opportunity  of  escape  from 
enemies.  3.  Catechu  (p.  318)  furnishes  a brown  coloring-matter. 

Black. — 1.  Blacklead  (p.  26),  bone-black  (p.  95),  or  ivory-black, 
and  lampblack,  the  latter  a deposited  soot  from  incomplete  com- 
bustion of  resin  and  tar,  are  varieties  of  carbon.  2.  Burnt  sugar 
or  caramel  (p.  364).  3.  Indian  ink  is  usually  a dried  mixture  of 

fine  lampblack  and  size,  or  thin  glue.  4.  Black  ink  is  essentially 
tannates  and  gallates  of  iron  suspended  in  water  containing  a little 
gum  in  solution.  5.  Printer's  ink  is  well  boiled  linseed  or  other  oil, 
mixed  with  good  lampblack,  vermilion,  or  other  pigment.  6.  Black 
dyes  are  of  the  same  nature  as  ink. 

White  Pigments. — 1.  Chalk  or  Whiting  (p.  94).  2.  French 

chalk,  steatite,  or  soapstone,  a silicate  of  magnesium.  3.  Heavy 
white  (p.  87).  4.  Pearl-vdiite  (p.  224).  5.  Plaster  of  Paris  (p.  90). 
6.  Starch  (p.  355).  7.  White-lead  (p.  185).  8.  /Anc-white  (p.  113). 
9.  Oxides  of  tin  and  zinc  and  phosphate  of  calcium  are  employed 
for  giving  a white  opacity  to  glass. 

Aniline  Colors.  Coal-tar  colors. — Within  the  last  ten  years 
nearly  every  shade  of  color  seen  in  the  animal  or  vegetable  kingdoms 
has  been  successfully  imitated  by  certain  dyes  and  pigments  primarily 
derived  from  a mineral,  coal.  Coal  distilled  for  gas  furnishes  tar  or 
gas-tar.  Coal-tar  contains  some  aniline  ; but  especially  it  contains  a 
liquid  convertible  into  aniline,  namely  benzol  (C^-H^H),  first  discovered 
by  Faraday  in  compressed  oil-gas.  From  aniline,  by  oxidation, 
Bunge  obtained  the  violet  color-reaction,  the  body  producing  which 
Perkin  afterwards  studied  and  isolated,  and  manufactured  under  the 
name  of  mauve.  Aniline-red  [fuchsine,  magenta,  or  rosaniline), 
aniline-yellow,  aniline-green,  aniline-blue,  and,  in  short,  aniline-dyes, 
lakes,  and  pigments  of  every  hue  of  the  rainbow,  are  now  common 
articles  of  trade.  Their  application  has  revolutionized  the  arts  of 
the  dyer  and  color  printer. 


QUESTIONS  AND  EXERCISES. 

866.  Explain  the  production  of  color. 

867.  Mention  the  chief  yellow  coloring-matters. 

868.  What  is  annatto  ? 

869.  Name  the  colorific  constituent  of  madder. 

870.  State  the  source  of  Litmus. 

871.  Distinguish  between  Prussian  blue  and  Turnbulhs  blue. 

872.  How  is  blue  ultramarine  obtained  ? 

873.  Describe  the  coloring  principle  of  green  leaves. 

874.  By  what  agents  is  glass  colored  green  ? 

875.  Whence  is  sepia  obtained? 

876.  Describe  the  chemistry  of  black  ink. 

877.  Write  a few  sentences  on  aniline  colors. 


418 


CHEMICAL  TOXICOLOGY. 


CHEMICAL  TOXICOLOGY. 

In  cases  of  criminal  and  accidental  poisoning,  the  substances  pre- 
sented to  the  chemical  analyst  for  examination  are  usually  articles  of 
food,  medicines,  vomited  matters,  or  the  liver,  kidney,  intestines, 
stomach  and  contents,  removed  in  course  of  post-mortem  examina- 
tion. In  these  cases  some  special  operations  are  necessary  before  the 
poison  can  be  isolated  in  a state  of  sufficient  purity  for  the  applica- 
tion of  the  usual  tests;  for  in  most  instances  the  large  quantity  of 
animal  or  vegetable,  or,  in  one  word,  organic  matter  present  pre- 
vents or  masks  the  characteristic  reactions  on  which  the  tests  are 
founded.  These  operations  will  now  be  described  ;*  they  form  the 
chemical  part  of  the  subject  of  toxicology  {ro^vxov,  toxicon,  poison, 
and  ^6yo^,  logos,  discourse). 

Substances  occurring  in  the  form  of  an  apparently  definite  salt  or 
unmixed  with  organic  matter  need  no  special  treatment,  they  are 
analyzed  by  the  ordinary  methods  already  given,  attention  being 
restricted  to  poisonous  compounds  only. 

Examination  of  an  organic  mixture  suspected  to  con- 
tain: Mercury,  ArsenicuxM,  Antimony,  Lead,  Copper, 
OR  Zinc;  Sulphuric  Acid,  Nitric  Acid,  Hydrochloric 
Acid,  Oxalic  Acid,  or  Hydrocyanic  Acid;  Caustic 
Alkalies;  Strychnia  or  Phosphorus;  Morphia  or 
OTHER  Poisonous  Alkaloids. 

Preliminary  Examination. 

Odor.^  Appearance.^  Tante. — Smell  the  mixture,  with  the 
view  of  ascertaining  the  presence  or  absence  of  any  nota- 
ble quantity  of  free  hydrocyanic  acid.  Look  carefully  for 
any  small  solid  particles,  such  as  arsenic,  corrosive  subli- 
mate, or  verdigris,  and  for  any  appearance  which  may  be 
regarded  as  abnormal,  any  character  unusual  to  the  coffee, 
tea,  beer,  medicine,  vomit,  coats  of  stomach,  kidney,  liver, 
or  other  organ,  tissue,  or  solid  matter  under  examination. 
If  liquid  or  semifluid,  taste  the  mixture,  or  add  to  a small 
portion  some  solution  of  carbonate  of  sodium,  with  the 
view  of  ascertaining  by  excessive  sourness  or  strong  effer- 
vescence the  presence  of  any  large,  poisonous  quantity  of 
sulphuric,  nitric,  or  h3'drochloric  acid.  If  so  excessively 
alkaline  as  to  require  the  addition  of  a veiy  large  quantity 

* Materials  for  these  experiments  are  readily  obtained  for  educa- 
tional purposes  by  dissolving  the  poison  in  infusions  of  tea,  coffee, 
porter,  or  in  water  to  which  some  mucilage  of  starch  or  linseed-meal, 
pieces  of  bread,  potato,  and  fat  have  been  added. 


MERCURY,  ARSENICUM,  ANTIMONY,  ETC.  419 


of  acid  before  neutralization  is  effected,  a noxious  quantity 
of  a corrosive  or  caustic  alkali  is  present. 

Special  insti'uctions  may  induce  the  operator  to  suspect 
the  presence  of  one  particular  poison.  Direct  examina- 
tion for  the  latter  may  then  be  made,  either  at  once,  if  the 
substance  has  an  aqueous  character,  or  when  filtration 
or  treatment  with  warm  hydrochloric  or  acetic  acid  has 
afforded  a more  or  less  colorless  liquid. 

Fluids. — A vomit  or  the  contents  of  a stomach,  if  set 
aside  in  a long  narrow  vessel  (test-glass  or  ale-glass),  or, 
better,  exposed  on  a filter  during  a night,  will  often  yield 
a more  or  less  clear  limpid  portion  at  the  bottom  or  top  of 
the  solid  matter.  This  fluid  (separated  by  a pipette  or 
otherwise)  will  sometimes  respond  to  tests  without  further 
preparation,  and  always  requires  less  preparatory  treatment 
than  a semisolid  mixture.  If  none  passes  through  a filter, 
a portion  often  collects  in  the  upper  part. 

General  procedure. — If  the  preliminary  examination 
does  not  indicate  the  method  to  be  pursued,  proceed  as 
follows,  treating  a portion  (not  more  than  one-fourth)  of 
the  mixture  for  the  poisonous  metals,  another  for  the  acids, 
and  a third  for  alkaloids,  reserving  the  remainder  for  any 
special  experiments  which  may  suggest  themselves  in  the 
course  of  analysis. 

Examination  for  Mercury.^  Arsenicum.^  Antimony^  Lead^ 
Copper^  Zinc. 

If  a liquid,  acidulate  with  hydrochloric  acid  and  boil  for 
a short  time.  If  solid  or  semisolid,  cut  up  the  matter  into 
small  pieces,  add  enough  water  to  form  a fluid  mixture,  stir 
in  ten  or  twenty  per  cent,  of  ordinary  liquid  hydrochloric 
acid,  and  boil  until,  from  partial  aggregation  and  solution 
of  tlie  solid  matter,  filtration  can  be  easily  effected. 

Heat  a portion  of  the  clear  liquid  with  a thin  piece  of 
bright  copper  or  copper  gauze,  about  an  inch  long  and  a 
quarter  of  an  inch  broad,  for  about  ten  or  twenty  minutes  ; 
metallic  mercury.^  arsenicum^  or  antimony  will  be  deposited 
on  the  copper,  darkening  it  considerably  in  color.  Pour 
off  the  liquid  from  the  copper,  carefully  rinse  the  latter 
with  a little  cold  water,  dry  the  piece  of  metal  by  holding 
it  over  or  near  a flame  (using  fingers,  not  tongs,  or  it  may 
become  sufficiently  hot  for  loss  of  mercury  or  arsenicum  to 
occur  by  A^olatilizatioii),  introduce  it  into  a narrow  test- 
tube  or  piece  of  glass  tubing  closed  at  one  end,  and  heat 


420 


CHEMICAL  TOXICOLOGY. 


the  bottom  of  the  tube  in  a flame,  holding  it  horizontally 
that  the  upper  part  of  the  tube  may  be  kept  cool,  and  par- 
tially closing  the  mouth  with  the  finger  to  prevent  escape 
of  vapor.  Under  these  circumstances  an}’’  Mercury  will 
volatilize  from  the  copper  and  condense  on  the  cool  part  of 
the  tube  in  a ring  or  patch  of  white  sublimate,  readily 
aggregating  into  visible  globules  on  being  pressed  b}"  the 
side  of  a thin  glass  rod  inserted  into  the  tube ; Arsenicum 
will  volatilize  from  the  copper,  and,  absorbing  oxygen  from 
the  air  in  the  tube,  condense  on  the  cool  part  of  the  glass 
in  a ring  or  patch  of  white  sublimate  of  arsenic  (gray  or 
even  darker  if  much  arsenicum  as  well  as  arsenic  be  pre- 
sent), not  running  into  globules  when  rubbed,  but  occur- 
ring in  small  crystals,  the  characteristic  octahedral  form 
of  which  is  readily  seen  by  aid  of  a good  hand  lens,  or  the 
lower  part  of  a microscope ; Antimony  volatilizes  from  the 
copper,  if  strongly  heated,  and,  absorbing  ox3'gen,  immedi- 
ately condenses  as  a slight  white  deposit  close  to  the  metal. 

Confirmatory  Tests. — 1.  Nothing  short  of  the  production  of 
globules  should  be  accepted  as  evidence  of  the  presence  of  mercury. 

It  will  usually  have  existed  as  corrosive  sublimate. 

2.  To  confirm  indications  of  the  presence  of  arsenicum,  a portion 
of  the  acid  liquid  may  be  subjected  to  the  hydrogen  tests  (pp.  149, 
151)  ; or  the  tube  containing  the  white  crystalline  arsenic  may  be 
broken,  and  the  part  on  which  the  sublimate  occurs  boiled  for  some 
time  in  water,  and  the  hydrosulphuric-acid,  ammonio-nitrate-of-silver, 
and  ammonio-sulphate-of-copper  tests  (pp.  151,  153)  applied  to  the 
aqueous  solution. 

3.  For  antimony,  a portion  of  the  acid  liquid  must  always  be  intro- 
duced into  the  hydrogen-apparatus  with  the  usual  precautions.  ( Vide  I 

p.  160.)  •: 

For  Lead  and  Copper^  pass  hj^drosulphuric  acid  gas 
through  the  clear  acid  liquid  for  some  time,  warming  the 
liquid  if  no  precipitate  is  produced,  or  diluting  and  par-  j 
tially  neutralizing  the  acid  by  ammonia  if  much  acid  has 
been  added.  Collect  on  a filter  any  black  precipitate  that  |i 
may  have  formed  ; wash,  dissolve  in  a few  drops  of  aqua  ! 
regia,  dilute,  and  apply  the  tests,  such  as  ammonia  for 
copper,  sulphuric  acid  for  lead,  and  any  other  of  the  or-  r 
dinary  reagents  (pp.  168,  189). 

Copper  may  often  be  at  once  detected  in  a small  quantity  of  j 
acidulated  liquid  by  immersing  the  point  of  a penknife  or  a piece  of  j 
bright  iron  wire — a deposit  of  copper,  in  its  characteristic  color,  i, 
quickly  or  slowly  appearing,  according  to  the  amount  present  (p.  ji 

168).  l! 


MINERAL  ACIDS,  OXALIC  ACID,  ETC.  421 

Zinc, — To  the  acid  liquid  through  which  sulphuretted 
hydrogen  has  been  passed,  add  excess  of  ammonia  (or  to 
the  original  acid  fluid  add  excess  of  ammonia,  and  then 
sulphydrate  of  ammonium)  ; a precipitate  falls  which  may 
contain  alumina,  phosphates,  and  zinc ; it  is  usually  black- 
ish from  the  presence  of  sulphide  of  iron.  Collect  the 
precipitate  on  a filter,  wash,  dissolve  in  a little  hydro- 
chloric acid,  add  a few  drops  of  nitric  acid,  boil,  pour  in 
excess  of  ammonia,  filter,  and  test  the  filtrate  with  sulphy- 
drate of  ammonia — a white  precipitate  indicates  zinc. 

Examination  for  Mineral  Acids,^  Oxalic  Acid^  or 
Hydrocyanic  Acid. 

To  detect  Hydrochloric.^  Nitric.^  or  Sulphuric  Acid  in 
any  liquid  containing  organic  matter,  dilute  with  water 
and  apply  to  small  portions  the  usual  tests  for  each  acid, 
disregarding  indications  of  small  quantities.  (Vide  pp. 
240,  256,  m.) 

Excessive  sourness,  copious  evolution  of  carbonic  acid  gas  on  the 
addition  of  carbonate  of  sodium,  and  abundant  evidence  of  acid  on 
applying  the  various  tests  to  small  portions  of  the  fluid  presented  for 
analysis,  collectively  form  sufficient  evidence  of  the  occurrence  of  a 
poisonous  amount  of  either  of  the  three  common  mineral  acids.  Small 
quantities  of  the  hydrochloric,  nitric,  and  sulphuric  radicals  occurring 
as  metallic  salts  or  acids,  are  common  normal  constituents  of  food, 
hence  the  direction  to  disregard  insignificant  indications.  If  the 
fluid  under  examination  is  a vomit  or  the  contents  of  a stomach,  and 
an  antidote  has  been  administered,  free  acid  will  not  be  found,  but, 
instead,  a large  amount  of  corresponding  salt. 

For  Oxalic  Acid.,  filter  or  strain  a portion  of  the  liquid, 
if  not  already  clear,  and  add  solution  of  acetate  of  lead  so 
long  as  a precipitate  occurs ; collect  the  precipitate,  which 
is  partly  oxalate  of  lead,  on  a filter,  wash,  transfer  it  to  a 
test-tube  or  test-glass,  add  a little  water,  and  pass  hydro- 
sulphuric  gas  through  the  mixture  for  a short  time ; the 
lead  is  thus  converted  into  the  insoluble  form  of  sulphide, 
while  oxalic  acid  is  set  free  in  the  solution.  Filter,  boil 
to  get  rid  of  hydrosulphuric  gas,  and  apply  the  usual  tests 
for  oxalic  acid  (see  p.  282)  to  the  clear  filtrate. 

The  contents  of  a stomach  containing  oxalic  acid  are  often 
of  a dark-brown  color  with  a tinge  of  green  (altered  blood 
and  mucus),  and  the  viscid  mixture  generally,  though 
slowly,  affords  some  clear,  limpid,  almost  colorless  liquid 
by  filtration  on  standing. 

For  Hydrocyanic  Acid.^  the  three  chief  tests  may  be  ap- 
36 


422 


CHEMICAL  TOXICOLOGY. 


plied  at  once  to  the  liquid  or  semiliquid  organic  mixture, 
whether  it  has  an  odor  of  hydrocyanic  acid  or  not.  First: 
half  fill  a small  porcelain  crucible  with  the  material,  add 
eight  or  ten  drops  of  strong  sulphuric  acid,  stir  gently 
with  a glass  rod,  and  invert  ever  the  mouth  of  the  crucible 
a watch-glass  moistened  with  a small  drop  of  solution  of 
nitrate  of  silver;  a white  film  on  the  silver  solution  is 
probably  cyanide  of  silver,  formed  by  the  action  of  the 
gaseous  hydrocy^anic  acid  on  the  nitrate  of  silver.  Second  : 
prepare  a small  quantit}^  of  the  organic  mixture  as  before, 
slightly  moistening  the  centre  of  the  watch-glass  with 
solution  of  potash;  here  again  the  heat  generated  by  the 
action  of  the  strong  acid  is  sufficient  to  volatilize  some  of 
the  hydroc^^anic  acid,  which,  reacting  on  the  potash,  forms 
cyanide  of  potassium.  On  removing  the  watch-glass  and 
stirring  into  it  successively  solution  of  a ferrous  salt,  a 
ferric  salt,  and  hydrochloric  acid,  flocks  of  prussian  blue 
are  produced  if  hydrocyanic  acid  is  present.  Third:  pro- 
ceed as  before,  moistening  the  watch-glass  with  sulphydrate 
of  ammonium  ; after  exposure  to  the  hydrocyanic  gas  for 
five  or  ten  minutes,  add  a drop  of  solution  of  ammonia, 
evaporate  to  dryness  at  a low  temperature,  and  add  a drop 
of  hydrochloric  acid  and  of  solution  of  perchloride  of  iron  ; 
a blood-red  color,  due  to  sulphocj^anate  of  iron,  is  pro- 
duced if  cyanogen  is  present. 

If  the  above  reactions  are  not  well  marked,  the  organic  mixture 
may  be  carefully  and  slowly  distilled  in  a small  retort,  the  neck  of 
which  passes  into  a bottle  .and  dips  beneath  the  surface  of  a little 
w^ater  at  the  bottom  of  the  bottle,  and  the  reagents  then  applied  to 
separate  portions  of  the  distillate. 

The  examination  of  organic  mixtures  for  hydrocyanic  acid  must 
be  made  without  delay,  as  the  poison  soon  begins  to  decompose,  and 
in  a day  or  two  is  usually  destroyed. 

Examination  for  Phosphorus. 

A paste  containing  phosphorus  is  commonly  employed  for  destroy- 
ing vermin.  In  cases  of  poisoning  the  phosphorus  is  commonly  in  suf- 
ficient quantity  to  be  recognized  by  its  characteristic  unpleasant 
smell.  A stomach  in  which  it  occurs  not  unfrequently  exhibits 
slight  luminosity  if  opened  in  a dark  room.  When  the  phosphorus 
is  too  small  in  quantity  or  too  much  diffused  to  afford  this  appearance, 
a portion  of  the  material  is  placed  in  a flask,  water  acidulated  by 
sulphuric  acid  added,  a long  wide  glass  tube  fitted  to  the  neck  of 
the  flask  by  a cork,  and  the  mixture  gently  boiled.  If  phosphorus  is 
prcvsent  (even  I part  in  2,000,000,  according  to  De  Try)  the  top  of 
the  column  of  steam  as  it  condenses  in  the  tube  will  appear  distinctly 


STRYCHNIA  AND  MORPHIA. 


423 


phosphorescent  when  viewed  in  a dark  room.  From  its  liability  to 
oxidation  phosphorus  cannot  be  detected  after  much  exposure  of  an 
organic  mixture  to  air. 

Examination  for  Strychnia  and  Morphia. 

Strychnia. — If  solid  or  semisolid,  digest  the  matter  with 
water  and  about  10  per  cent,  of  hydrochloric  acid  till  fluid, 
filter,  evaporate  to  dryness  over  a water-bath.  If  the  or- 
ganic mixture  is  already  liquid,  it  is  simply  acidulated  with 
hydrochloric  acid  and  evaporated  to  dryness.  The  acid 
residue  is  next  treated  with  spirit  of  wine  as  long  as  any- 
thing is  dissolved,  the  filtered  tincture  evaporated  to  dry- 
ness over  the  water-bath,  and  the  residue  digested  in  water 
and  filtered.  This  slightly  acid  aqueous  solution  must  now 
be  rendered  alkaline  by  ammonia,  and  well  shaken  in  a 
bottle  or  long  tube  with  about  half  an  ounce  of  chloroform, 
and  set  by  till  the  chloroform  has  subsided.  The  chloro- 
form (which  contains  the  strychnia)  is  then  removed  by  a 
pipette,  the  presence  of  any  aqueous  liquid  being  carefully 
avoided,  and  evaporated  to  diyness  in  a small  basin  over  a 
water-bath,  the  residue  moistened  with  concentrated  sul- 
phuric acid,  and  the  basin  kept  over  the  water-bath  for 
sev^eral  hours.  (It  is  highly  important  that  the  sulphuric 
acid  used  in  this  operation  should  be  free  from  nitrous 
compounds.  Test  the  acid,  therefore,  by  adding  powdered 
sulphate  of  iron,  which  becomes  pink  if  nitrous  bodies  are 
present.  If  these  are  found,  the  acid  should  be  purified 
by  strongly  heating  with  sulphate  of  ammonium,  seventy 
or  eighty  grains  to  a pint.)  The  charred  material  is  ex- 
hausted with  water,  filtered,  excess  of  ammonia  added, 
the  filtrate  shaken  with  about  a quarter  of  an  ounce  of 
chloroform,  the  mixture  set  aside  for  the  chloroform  to 
separate,  and  the  chloroform  again  removed.  If,  on  evapo- 
rating a small  portion  of  this  chloroform  solution  to  dry- 
ness, adding  a drop  of  sulphuric  acid  to  the  residue,  and 
warming,  any  darkening  in  color  or  charring  takes  place, 
the  strychnia  is  not  sufficiently  pure  for  chemical  detection; 
in  that  case  the  rest  of  the  chloroform  must  be  removed 
by  evaporation,  and  the  residue  redigested  in  warm  sul- 
phuric acid  for  two  or  three  hours.  Dilution,  neutraliza- 
tion of  acid  by  ammonia,  and  agitation  witli  chloroform  are 
again  practised,  and  the  residue  of  a small  portion  of  the 
chloroform  solution  once  more  tested  with  sulphuric  acid. 
If  charring  still  occurs,  the  treatment  must  be  repeated  a 


424 


CHEMICAL  TOXICOLOGY. 


third  time.  Finally  a part  of  the  chloroform  solution  is 
taken  up  by  a pipette,  and  drop  after  drop  evaporated  on 
one  spot  of  a porcelain  crucible-lid  until  a fairly  distinct 
dry  residue  is  obtained.  A drop  of  sulphuric  acid  is 
placed  on  the  spot,  another  drop  placed  near,  a minute 
fragment  of  red  chromate  of  potassium  placed  in  the 
second  drop,  and  when  the  acid  has  become  tinged  with 
the  chromate,  one  drop  drawn  across  the  other ; the  char- 
acteristic evanescent  purple  color  is  then  seen,  if  strychnia 
is  present.  Other  tests  {vide  p.  248)  may  be  applied  to 
similar  spots. 

This  is  Girdwood  and  Kogers’s  method  for  the  detection  of  strych- 
nia when  mixed  wnth  organic  matter.  It  is  tedious  but  trustworthy, 
and,  though  apparently  complicated,  very  simple  in  principle ; thus: 
strychnia  is  soluble  in  acidulated  water  or  alcohol,  or  in  chloroform, 
readily  removed  from  an  alkaline  liquid  by  agitation  with  chloroform, 
and  not  charred  or  otherwise  attacked  when  heated  to  212^  F.  with 
sulphuric  acid : much  of  the  organic  matter  of  the  food  is  insoluble 
in  water ; of  that  soluble  in  w^ater,  much  is  insoluble  in  alcohol ; and 
of  that  soluble  in  both  menstrua,  all  is  charred  and  destroyed  by 
warm  sulphuric  acid  in  a shorter  or  longer  time. 

Morphia^  and  the  Meconic  Acid  with  which  it  is  associ- 
ated in  Opium, — To  the  liquid  or  the  semifluid  mixture 
warmed  for  some  time  with  a small  quantity  of  acetic  acid, 
filtered,  and  concentrated  if  necessary,  add  solution  of 
acetate  of  lead  until  no  further  precipitate  is  produced. 
Filter  and  examine  the  precipitate  for  meconic  acid,  reserv- 
ing t\\Q  filtrate  for  the  detection  of  morphia. 

The  Precipitate, — Wash  the  precipitate  (meconate  of 
lead,  etc.)  with  water,  place  it  in  a test-tube  or  test-glass 
with  a small  quantity  of  water,  pass  hydrosulphuric  acid 
gas  through  the  mixture  for  a short  time,  filter,  slightly 
warm  in  a small  basin,  well  stirring  to  promote  removal  of 
excess  of  the  gas,  and  add  a drop  of  neutral  solution  of 
perchloride  of  iron  ; a red  color,  due  to  the  formation  of 
meconate  of  iron,  is  produced  if  meconic  acid  is  present. 
This  color  is  not  destroyed  on  boiling  the  liquid,  as  is  the 
case  with  ferric  acetate,  nor  is  it  bleached  by  solution  of 
corrosive  sublimate,  thus  distinguishing  it  from  the  ferric 
sulphocyanate.  It  is  discharged  by  hydrochloric  acid. 

The  Filtrate, — The  solution  from  which  meconic  acid 
has  been  removed  by  acetate  of  lead  is  evaporated  to  a 
small  bulk  over  a water-bath,  excess  of  carbonate  of  potas- 
sium added,  and  evaporation  continued  to  dryness.  Tlie 
residue  is  then  treated  with  alcoiiol,  which  dissolves  the 


CHEMICAL  TOXICOLOGY. 


425 


morphia.  The  alcoholic  solution  evaporated  similarly  may 
leave  the  morphia  sufficiently  pure  for  the  application  of 
the  usual  tests  {vide  page  341)  to  small  portions  of  the 
residue.  If  no  reaction  is  obtained,  add  a drop  of  sul- 
phuric acid  and  a little  water  to  the  residue  and  shake  with 
ether,  in  which  the  salt  of  morphia  is  insoluble.  The  treat- 
ment with  ether  may  be  repeated  until  nothing  more  is 
removed,  the  acid  aqueous  liquid  saturated  with  carbonate 
of  potassium,  the  mixture  evaporated  to  drjmess,  the  resi- 
due digested  in  alcohol,  filtered,  and  portions  of  the  alco- 
holic liquid  evaporated  to  obtain  spots  of  morphia  for  the 
application  of  the  ordinary  tests. 

if  much  organic  matter  is  believed  to  remain  in  the  fil- 
trate after  the  acetate  of  lead  treatment,  or  if  a considerable 
excess  of  acetate  of  lead  has  been  employed,  the  filtered 
liquid  should  be  subjected  to  a current  of  sulphuretted 
h3alrogen  until  no  more  sulphide  of  lead  is  precipitated, 
the  mixture  filtered,  and  the  filtrate,  with  the  washings  from 
the  sulphide  of  lead,  evaporated  to  a small  bulk,  excess  of 
carbonate  of  potassium  added,  the  whole  well  mixed  and 
agitated  with  twice  or  thrice  its  bulk  of  a mixture  of  ether 
and  acetic  ether  (ether  alone  might  not  dissolve  the  mor- 
phia). On  standing  the  ethereal  liquid  rises  to  the  surface  ; 
it  is  carefully  removed,  evaporated  to  dryness,  and  the 
residue  tested  or  further  purified  in  the  manner  described 
in  the  preceding  paragraph. 

The  examination  for  morphia  must  be  conducted  with  great  care, 
and  with  as  large  a quantity  of  material  as  can  be  spared ; for  its 
isolation  from  other  organic  matter  is  an  operation  of  considerable 
difficulty,  especially  when  only  a minute  proportion  of  alkaloid  is 
present.  Fortunately  the  detection  of  meconic  acid  does  not  include 
similar  difficulties ; and,  as  its  reactions  are  quite  characteristic,  its 
presence  is  held  to  be  strong  evidence  of  the  existence  of  opium  in 
an  organic  mixture. 

Examination  for  Other  Poisonous  Alkaloids* 

Stasis  Process. — Minutely  subdivide  any  solid  matter; 
to  this  and  the  liquid  portion  of  the  vomit,  etc.,  add  about 
twice  their  weight  of  the  strongest  spirit  of  wine  contain- 
ing sufficient  tartaric  acid  to  fairly  acidify  the  mixture.  Di- 
gest the  whole  in  a fiask  at  a temperature  of  150°  or  160°  F. ; 
set  aside  to  cool;  filter.  The  solution,  which  will  contain 
the  whole  of  the  alkaloid,  should  then  be  evaporated  nearly 
to  dryness  in  vacuo.,  or  at  all  events  at  a temperature  not 

36* 


426 


CHEMICAL  TOXICOLOGY. 


exceeding  100°  F.,  lest  volatile  alkaloids  should  be  dissi- 
pated. The  residue  is  next  exhausted  with  cold  anhydrous 
alcohol ; filtered  ; and  the  filtrate  evaporated  to  dryness 
with  the  precautions  already  stated.  The  extract  is  dis- 
solved in  a very  small  quantity  of  water,  treated  with  excess 
of  powdered  bicarbonate  of  sodium  or  potassium,  and  w’ell 
shaken  with  five  or  six  times  its  volume  of  pure  ether  (with 
perhaps  a little  acetic  ether).  This  ethereal  liquid  contains 
the  alkaloid.  Small  portions  should  be  evaporated  in 
watch-glasses  and  tasted,  or  tested  physically  and  chemi- 
cally, according  as  the  knowledge  of  collateral  circum- 
stances by  the  operator,  or  his  experience,  or  the  reactions 
recorded  on  pp.  349-354,  may  suggest. 

If  a volatile  alkaloid  (conia,  nicotia,  hyosc^^amia,  lobe- 
lina)  is  indicated,  the  ethereal  solution,  which  may  still 
contain  animal  matter,  is  removed,  agitated  with  aqueous 
solution  of  potash,  decanted,  and  shaken  with  pure  diluted  ! 
sulphuric  acid.  On  standing,  the  aqueous  portion,  contain-  | 
ing  the  alkaloid  as  acid  sulphate,  subsides ; the  upper  j 
ethereal  portion  containing  the  animal  matter  is  rejected  ; ! 
the  acid  aqueous  liquid  is  made  alkaline  with  caustic  potash  ! 
or  soda;  ether  added;  well  shaken;  the  ethereal  liquid  j 
decanted,  evaporated  to  dryness  in  vacuo ^ or  at  a low  tern-  I 
perature ; and  (to  get  rid  of  all  traces  of  ammonia)  again  | 
moistened  with  ether  and  dried.  The  residue  is  now  tested  j 
for  the  suspected  alkaloid  b3"  taste,  smell,  and  the  applica-  i 
tion  of  appropriate  reagents  (pp.  349-354). 

If  a non-volatile  alkaloid  (aconitia,  atropia,  brucia,  col-  f 
chicia,  emetia,  physostigmia,  solania,  veratria,  as  well  as 
morphia,  codeia,  and  strychnia)  is  indicated,  further  purifi- 
cation is  effected  by  decanting  the  ethereal  liquid  from  the 
lower  aqueous  solution  of  bicarbonate  of  sodium,  removing 
the  ether  by  evaporation,  digesting  the  residue  in  alcohol, 
filtering,  evaporating  the  alcohol,  treating  the  residue  with 
dilute  sulphuric  acid,  setting  aside  for  a few  hours,  filtering,  , 
concentrating,  adding  powdered  carbonate  of  potassium, 
and  finall3^  anhydrous  alcohol.  The  alcoholic  liquid,  on 
evaporation,  ^fields  the  alkaloid  in  a fit  state  for  testing  in 
the  manner  alread}^  stated. 

Sonnenschien^s  Process.  — Digest  with  diluted  hydro- 
chloric acid,  evaporate  to  the  consistence  of  s^’nip,  dilute, 
set  aside  for  some  hours,  filter.  Add  solution  of  phospho- 
mol3^bdic  acid  so  long  as  any  precipitate  falls  or  cloudiness 
occurs;  collect  the  precipitate  on  a small  filter;  wash  it  with 
water  containing  phosphomolybdic  and  nitric  acid,  and, 


CHEMICAL  TOXICOLOGY. 


421 


while  still  moist,  place  it  in  a flask.  Decompose  this  com- 
pound of  phosphomolybdic  acid  and  alkaloid  by  adding 
caustic  baryta  until  the  stirred  mixture  is  distinctly  alka- 
line. Distil  off  volatile  alkaloids,  condensing  and  collect- 
ing by  help  of  a long  tube,  so  bent  that  the  apparatus  shall 
act  as  a retort,  the  end  of  the  tube  being  attached  to  a bulb 
or  a series  of  bulbs  containing  dilute  hydrochloric  acid. 
The  acid  liquid  evaporated  gives  a residue  of  hydrochlorates 
of  alkaloids.  The  latter  will  afford  characteristic  reactions 
with  the  tests  for  the  suspected  alkaloid,  and,  on  being 
moistened  with  baiyta-water  and  warmed,  will  afford  fumes 
of  volatile  alkaloids  whose  odor  is  usually  characteristic. 
The  residue  in  the  flask  will  contain  non-volatile  alkaloids. 
It  is  treated  with  carbonic  acid  gas  to  neutralize  and  pre- 
cipitate the  excess  of  baryta  as  insoluble  carbonate  of 
barium  ; the  mixture  is  evaporated  to  dryness  over  a water- 
bath  ; and  the  residue  digested  in  alcohol.  The  alcoholic 
solution  evaporated  generally  yields  the  alkaloids  in  a fit 
state  for  testing. 

Phosphomolybdic  acid  forms  with  ammonia,  in  acid  solutions,  a 
remarkably  insoluble  compound,  and  it  comports  itself  in  a similar 
manner  with  those  compounds  which  are  analogous  to  ammonia — the 
nitrogenized  organic  bases — consequently  forming  an  excellent  re- 
agent for  their  detection.  It  may  be  prepared  in  the  following 
manner : Molybdate  of  ammonium  is  precipitated  by  phosphate  of 
sodium;  the  yellow  precipitate,  having  been  washed,  is  diffused 
through  water,  and  heated  with  sufficient  carbonate  of  sodium  to  dis- 
solve it.  The  solution  is  then  evaporated  to  dryness,  and  calcined 
to  drive  off  the  ammonia.  In  case  any  of  the  molybdic  compound 
be  reduced  by  this  operation,  the  residue  must  be  moistened  with 
nitric  acid  and  again  calcined.  The  dry  mass  is  then  dissolved  in 
cold  water,  the  solution  strongly  acidulated  with  nitric  acid,  and 
water  added  until  ten  parts  of  the  solution  contain  one  of  the  dry 
salt.  The  liquid,  which  is  of  a golden-yellow  color,  must  be  pre- 
served from  ammoniacal  fumes.  It  precipitates  all  the  alkaloids 
(with  the  exception  of  urea)  when  a mere  trace  only  is  present.  The 
precipitates  are  yellow,  generally  flocculent,  insoluble  in  water, 
alcohol,  ether,  and  the  dilute  mineral  acids,  with  the  exception  of 
phosphoric  acid.  Nitric,  acetic,  and  oxalic  acids,  concentrated  and 
boiling,  dissolve  them.  These  compounds  are  decomposed  by  the 
alkalies,  certain  metallic  oxides,  and  the  alkaline  salts,  which  sepa- 
rate the  alkaloid.  To  give  an  idea  of  the  sensibility  of  this  reagent, 
it  may  be  stated  that  the  0.000071  gramme  of  strychnia  gives  an  ap- 
preciable precipitate  with  one  cubic  centimetre  of  the  solution  of 
phosphomolybdic  acid. 


428 


CHEMICAL  TOXICOLOGY. 


ANTIDOTES. 

Vide  “Antidote”  in  the  Index. 


QUESTIONS  AND  EXERCISES. 

878.  In  examining  food  and  similar  matter  for  poison,  why  must 
not  the  ordinary  tests  for  the  poison  be  at  once  applied  ? 

879.  What  preliminary  operations  should  be  performed  on  a 
vomit  in  a case  of  suspected  poisoning  ? 

880.  How  would  you  proceed  in  searching  for  corrosive  sublimate 
in  wine  ? 

881.  By  what  series  of  operations  ’would  you  satisfy  yourself  of  the 
presence  or  absence  of  arsenic  in  the  contents  of  a stomach  ? 

882.  Describe  the  treatment  to  which  decoction  of  coffee  should 
be  subjected  in  testing  it  for  tartar-emetic. 

883.  State  the  method  by  which  the  occurrence  of  lead  in  water  is 
demonstrated. 

884.  Give  a process-  for  the  detection  of  copper  in  jam. 

885.  How  would  you  detect  zinc  in  a vomit  ? 

88G.  How  may  the  presence  o|  a poisonous  quantity  of  sulphuric 
acid  in  gin  be  proved  ? 

887.  In  examining  ale  for  free  nitric  acid  what  reactions  would  be 
selected  ? 

888.  Show  how  you  would  conclude  that  a dangerous  quantity  of 
hydrochloric  acid  had  been  added  to  cider. 

889.  Describe  the  manipulations  necessary  in  testing  for  hydro- 
cyanic'4ci'd  in  the  contents  of  a stomach. 

890.  By  what  method  is  oxalic  acid  discovered  in  infusion  of 
coffee  ? 

891.  How  is  the  phosphorus  detected  in  organic  mixtures  ? 

892.  Give  the  process  by  which  strychnia  is  isolated  from  partially 
digested  food. 

893.  Mention  the  experiments  by  which  the  presence  of  laudanum 
in  porter  is  demonstrated. 

894.  Name  the  appropriate  antidotes  in  cases  of  poisoning  by : 
a,  alkaloids;  antimonials ; c,  arsenic;  d,  barium  salts;  e,  copper 
compounds;  /,  hydrochloric  acid;  g,  hydrocyanic  acid;  /i,  prepara- 
tions of  lead  ; i,  corrosive  sublimate  ; nitric  acid  ; k,  oxalic  acid  ; /, 
salts  of  silver ; m,  oil  of  vitriol ; n,  tin  liquors ; o,  zinc  solutions ; p, 
carbolic  a^id. 


MORBID  URINE  — ALBUMEN. 


429 


EXAMINATION  OF  MORBID  URINE  AND 
CALCULI. 

The  various  products  of  the  natural  and  continuous  decay  of 
animal  tissue  and  the  refuse  matter  of  food  are  eliminated  from  the 
system  chiefly  as  faeces,  urine,  and  expired  air.  Air  exhaled  from  the 
lungs  carries  off  from  the  blood  much  carbon  (about  8 ounces  in  24 
hours),  in  the  form  of  carbonic  acid  gas,  and  some  aqueous  vapor — 
the  latter,  together  with  a small  amount  of  oily  matter,  also  escaping 
by  the  skin.  Directing  the  breath  to  a cold  surface  renders  moisture 
evident ; and  breathing  through  a tube  into  lime-water  demonstrates 
the  presence  of  a considerable  quantity  of  carbonic  acid  gas.  The 
faeces  consist  mainly  of  the  insoluble  debris  of  the  system,  the  solu- 
ble matters  and  water  forming  the  urine.  These  excretions  vary  con- 
siderably, according  to  the  food  and  general  habits  of  the  individual 
and  external  temperature.  But  in  disease  the  variations  become 
excessive ; their  detection  by  the  medical  practitioner,  or  by  the 
pharmacist  for  the  medical  practitioner,  is  therefore  a matter  of  im- 
portance. 

A complete  analysis  of  faeces,  urine,  or  expelled  air  cannot  be  per- 
formed in  the  present  state  of  our  knowledge.  Nor  can  any  analysis 
of  faeces  or  air  be  made  with  sufficient  ease  and  rapidity  to  be  prac- 
tically available  in  medical  diagnosis.  But  with  regard  to  urine, 
certain  abnormal  substances  and  abnormal  quantities  of  normal  con- 
stituents may  be  chemically  detected  in  the  course  of  a few  minutes 
by  any  one  having  already  some  knowledge  of  chemical  manipulation. 

Healthy  human  urine  contains,  in  1000  parts,  957  of  water,  14  of 
urea,  1 of  uric  acid,  15  of  other  organic  matter,  and  13  of  inorganic 
salts.  The  acidity  of  urine  Thudichum  considers  to  be  due  to  cryj)- 
tophanic  acid,  H2O5H7NO5. 

Examination  of  Morbid  Urine  for  Albumen,  Sugar, 

Bile,  and  Excess  of  Urea  ; and  Urinary  Sediment 

FOR  Urates  (or  Lithates),  Phosphates,  Oxalate  of 
Calcium,  and  Uric  Acid. 

Albumen — To  detect  albumen-,  acidulate  a portion  of  the 
clear  urine  in  a test-tube  with  a few  drops  of  acid  (to  keep 
phosphates  in  solution — nitric  is  best,  acetic  not  so  good) 
and  boil;  flocks  or  coagula  will  separate  if  albu  nen  be 
present. 

This  experiment  should  first  be  made  on  normal  urine  c(  ntaining 
a drop  or  two  of  solution  of  white  of  egg.  A coagulum  of  pure 
albumen  is  white,  greenish  if  bile  pigment  is  present,  and  brownish- 
red  if  the  urine  contains  blood.  The  influence  of  acids  and  alkalies 
on  the  precipitation  of  albumen  is  noticed  on  page  39G. 


430 


MORBID  URINE 


The  occurrence  of  albumen  in  the  urine  may  be  temporary  and  of 
but  little  importance  ; or  it  may  indicate  the  existence  of  a serious 
affection,  known  as  Bright’s  disease. 

Sugar. — To  a portion  of  the  clear  urine  in  a test-tube 
add  five  or  ten  drops  of  solution  of  sulphate  of  copper ; 
pour  in  solution  of  potash  or  soda  until  the  precipitate  first 
formed  is  redissolved  ; slowly  heat  the  solution  to  near  the 
boiling-point ; a yellow,  yellowish-red,  or  red  precipitate 
(cuprous  oxide)  is  formed  if  sugar  is  present. 

This  experiment  should  first  be  made  on  urine  containing  a drop 
or  two  of  solution  of  grape-sugar  (page  361).  The  hydrate  of  cop 
per  precipitated  by  the  alkali  is  insoluble  in  excess  of  pure  potash 
or  soda,  but  readily  dissolves  if  organic  matter,  especially  sugar,  is 
present.  The  copper  salt  may  not  contain  iron. 

Other  tests  may  be  applied  if  necessary  (vide  page  361). 

A minute  amount  of  sugar  is  said  to  occur  in  normal  urine  and  a 
disfinct  trace  is  occasionally  present.  In  larger  quantities  it  is  a 
characteristic  constituent  of  the  urine  of  diabetic  patients,  greatly 
increasing  the  specific  gravity  of  the  excretion.  Small  hydrometers 
(termed  urinometers)  are  commonly  employed  for  quickly  and  readily 
ascertaining  the  specific  gravity  of  urine  ; they  range  from  1000  to 
1050,  the  interval  of  1015  to  1025  being  marked  as  “ H.  S.,”  or 
healthy  state.  (Vide  “Specific  Gravity’^f and  “Hydrometers”  in 
Index.) 

Bile. — This  is  best  detected  by  the  general  test  (Pettenkofer’s) 
described  on  pa^giiAfif  • ^ little  of  the  urine  may  be  placed  on  a 

white  plate  an®  sti^ong  citric  acid  dropped  on  it ; a peculiar  play  of 
colors — green,  yello^w,  violet,  etc. — occurs  if  (the  coloring  matter  of) 
bile  is  present. 

Excels  of  Urea. — Nearly  one-half  of  the  solid  matter  in 
the  urine  is  urea.  Its  proportion  varies  considerably;  but 
per  cent,  may  be  regarded  as  an  average  amount.  Con- 
centrate urine  slightly  by  evaporation  in  a small  dish,  pour 
the  liquid  into  the  test-tube,  set  the  tube  aside  till  cold,  or 
cool  it  by  letting  cold  water  run  over  the  outside,  add  an 
equal  bulk  of  strong  nitric  acid  and  again  set  aside;  scaly 
crystals  of  nitrate  of  urea  are  deposited  more  or  less 
quickly. 

With  regard  to  the  amount  of  urea  in  urine,  it  is  impossible  to 
sharply  define  excess  or  deficiency.  If  nitric  acid  gives  crystals' 
without  concentration,  excess  is  certainly  present.  A rough  estimate 
may  be  formed  by  mixing  a few  drops  of  the  urine  and  acid  on  a 
piece  of  glass  and  setting  aside ; the  time  which  elapses  before  crys- 
tals form  is  an  indication  of  the  quantity  in  the  specimen.  The  time 
will  vary  according  to  the  temperature  and  state  of  moisture  of  the 
atmosphere;  but  with  care  some  useful  comparative  results  may  iip 
this  way  be  obtained. 


UREA. 


431 


Tests. — Urea  in  solution  in  water  may  be  detected  by  the  above 
reaction  with  nitric  acid,  and  by  the  readiness  with  which  it  yields 
ammonia  on  being  boiled  with  alkalies.  In  putrid  urine  its  conver- 
sion into  an  ammoniacal  salt  has  already  been  effected. 

CH.N^O  + = (NHJ2CO3. 

Urea.  Water.  Garb,  of  ammon. 

Formula  of  Urea. — The  empirical  formula  of  urea  is  CH^N20. 

(CO)"] 

Its  rational  formula  may  be  thus  written: — H2  VNg;  that  is, 

II J 

it  may  fie  regarded  as  one  of  the  organic  bases  already  referred  to, 
a primary  diamine,  in  which  the  bivalent  radical  CO  occupies  the 
place  of  H2.  The  other  atoms  of  hydrogen  may  be  displaced  by 
various  radicals,  and  many  compound  ureas  be  thus  obtained. 

Artificial  Urea. — Urea  may  be  prepared  artificially  by  Williams’s 
modification  of  Wohler’s  method.  Cyanide  of  potassium,  of  the  best 
commercial  quality  (containing  about  90  per  cent,  of  real  cyanide), 
is  fused  at  a very  low  red  heat  in  a shallow  iron  vessel ; red  lead 
is  added  in  small  quantities  at  a time,  the  temperature  being  kept 
down  by  constant  stirring.  When  the  red  lead  ceases  to  cause  fur- 
ther action  the  mixture  (cyanate  of  potassium  and  lead)  is  allowed 
to  cool,  the  product  finely  powdered,  exhausted  with  cold  water, 
nitrate  of  barium  added  till  no  more  precipitate  (carbonate  of  ba- 
rium) falls,  the  mixture  filtered,  and  the  filtrate  treated  with  nitrate 
of  lead  so  long  as  cyanate  of  lead  is  thrown  down.  The  latter  is 
thoroughly  washed,  and  dried  at  a low  temperature.  Equivalent 
quantities  of  cyanate  of  lead  and  sulphate  of  ammonium,  digested  in 
a small  quantity  of  water  at  a gentle  heat  and  filtered,  yield  a solu- 
tion from  which  urea  crystallizes  on  cooling. 

Another  Process. — Basaroff  has  found  that  urea  is  produced  when 
ordinary  carbonate  ^ ammonium  is  heated  in  hermetically  sealed 
tubes  to  aboul^fo^  F.  for  a few  hours.  The  same  chemist  had  pre- 
viously obtained  urea  by  similarly  heating  pure  carbamate  of  ammo- 
nium, so  that  fKe'source  of  the  urea  in  the  former  case  is  probably 
the  carbamate  of  ammonium  believed  to  occur  in  the  carbonate  (see 
page  78). 

NH,NH2C02  ~ H2O  = CH,N20. 


Urinary  Sediments. 

Warm  the  sediment  with  the  supernatant  urine  and  filter. 


Insoluble. 

Soluble. 

Phosphates,  oxalate  of  calcium,  and  uric 
acid. 

Warm  with  acetic  acid,  and  filter. 

Urates  — of  ammoni- 
um, calcium,  or  so- 
dium, chiefly  the 
latter. 

Insoluble. 

Oxalate  of  calcium  and  uric 
acid. 

Warm  with  hydrochloric 
acid,  filter. 

Soluble. 

Phosphates. 
Add  ammo- 
nia, white  ppt. 
= phosphate 
of  calcium,  or 

They  are  redeposit- 
ed as  the  liquid  cools, 
and  if  sufficient  in 
quantity  may  be  fur- 
ther examined  for  am- 
monium, calcium,  so- 
dium, and  the  uric 

Insoluble. 

Uric  acid. 
Apply  mu- 
rexid  test  (p. 
320). 

Soluble. 

Oxalate  of  cal- 
cium. 

May  be  re- 
precipitated by 
ammonia. 

ammonio-mag- 
nesium phos- 
phate, or  both. 

radical  by  the  appro- 
priate tests. 

Notes. — Urinary  deposits  are  seldom  of  a complex  character;  the 
action  of  heat  and  acetic  and  hydrochloric  acids  generally  at  once 
indicates  the  character  of  the  deposit,  rendering  filtration  and  pre- 
cipitation unnecessary. 

The  urates  are  often  of  a pink  or  red  color,  owing  ;to  the  presence 
of  a pigment  termed  purpurme;  hence  the  common  name  of  red 
gravel  for  such  deposits.  Purpurine  is  soluble  in  alcohol,  and  may 
be  removed  by  digesting  a red  deposit  in  that  solvent.  It  is  seldom 
necessary  to  determine  whether  the  urate  be  that  of  ammonium,  cal- 
cium, or  sodium  (see  also  Uric  Acid,  page  320). 

The  phosphate  of  calcium  and  the  ammonio-magnesium  phos- 
phate are  usually  both  present  in  a phosphatic  deposit,  the  magne- 
sium salt  forming  the  larger  proportion.  They  may,  if  necessary, 
and  if  sufficient  in  quantity,  be  separated  by  collecting  on  a filter, 
w^ashing,  and  boiling  with  solution  of  carbonate  of  sodium.  The 
carbonates  of  calcium  and  magnesium  thus  formed  are  collected  on  a 
filter,  washed,  dissolved  in  a drop  or  two  of  hydrochloric  acid — chlo- 
ride of  ammonium,  ammonia,  and  carbonate  of  ammonium  added, 
the  mixture  boiled  and  filtered ; any  calcium  originally  present  will 
then  remain  insoluble  as  carbonate  of  calcium,  w'hile  any  magnesium 
will  be  reprecipitated  from  the  filtrate  as  ammonio-magnesium  phos- 
phate on  the  addition  of  phosphate  of  sodium,  the  mixture  being 
also  well  stirred. The  chief  portion  of  excreted  phosphates  is  car- 

ried off  by  the  faeces,  that  remaining  in  the  urine  being  kept  in  solu- 


URINARY  SEDIMENTS. 


433 


tion  by  the  influence  of  acid  phosphate  of  sodium,  and,  frequently, 

lactic  acid. -Occasionally,  an  hour  or  two  after  a hearty  meal,  the 

urine  becomes  sufficiently  alkaline  for  the  phosphates  to  be  deposited, 

and  the  urine  when  passed  is  turbid  from  their  presence. The  am- 

moniacal  constituent  of  the  magnesium  salt  does  not  occur  normally, 
but  is  produced  from  urea  as  soon  as  urine  becomes  alkaline. 

Oxalate  of  calcium  is  seldom  met  with  in  excessive  amounts,  but 
very  often  in  small  quantities  mixed  with  phosphates. 

Free  uric  acid  is  in  most  cases  distinctly  crystalline,  and  nearly 
always  of  a yellow,  red,  or  brown  color. 

Artificial  Sediments. — For  educational  practice,  artificial  deposits 
may  be  obtained  as  follows:  1.  Eub  up  in  a mortar  a few^  grains  of 
serpent’s  excrement  (chiefly  urate  of  ammonium)  with  an  ounce  or 
two  of  urine  ; this  represents  a sediment  of  urates.  2.  Add  a few 
drops  of  solution  of  chloride  of  calcium  and  of  phosphate  of  sodium 
to  urine  ; the  deposit  may  be  regarded  as  one  of  phosphates.  3.  To 
an  ounce  or  two  of  urine  add  very  small  quantities  of  chloride  of 
calcium  and  oxalate  of  ammonium  ; the  precipitate  is  oxalate  of  cal- 
cium. 4.  To  urine  acidulated  by  hydrochloric  acid  add  a little  ser- 
pent’s excrement ; the  sediment  is  uric  acid. 

Other  deposits  than  the  foregoing  are  occasionally  observed.  Thus 
liippuric  acid  (HCgHgNO^),  a normal  constituent  of  human  urine, 
and  largely  contained  in  the  urine  of  herbivorous  animals,  is  some- 
times found  associated  with  uric  acid  in  urinary  sediment,  especially  in 
that  of  patients  whose  medicine  contains  benzoic  acid  (p.  301).  Its 
appearance,  as  observed  by  the  aid  of  the  microscope,  is  characteristic 
— namely,  slender,  four-sided  prisms,  having  pointed  ends.  Cystin 
(C3H7HSO2)  (from  xvguk;,  kustis,  a bladder,  in  allusion  to  its  origin) 
rarely  occurs  as  a deposit  in  urine.  It  is  not  soluble  in  warmed  urine 
or  dilute  acetic  acid,  and  scarcely  in  dilute  hydrochloric  acid,  hence 
would  be  met  with  in  testing  for  free  uric  acid.  It  is  very  soluble 
in  ammonia,  recrystallizing  from  a drop  of  the  solution  placed  on  a 
piece  of  glass  in  characteristic  microscopic  six-sided  plates.  Organ- 
ized sediments  may  be  due  to  the  corpuscles  of  pus,  mucus,  or  blood, 
fat-globules,  spermatozoa,  cylindrical  casts  of  the  tubes  of  the  kid- 
neys, epithelial  cells  from  the  walls  of  the  bladder,  or  foreign  matters, 
such  as  fibres  of  wool,  cotton,  small  feathers,  dust;  these  are  best 
recognized  by  the  microscope,  as  will  be  seen  by  the  following  para- 
graphs and  figures  on  the  microscopic  appearances  of  both  crystalline 
and  organized  urinary  sediments. 

Microscopic  Examination  of  Urinary  Sediments. 

Urine  containing  insoluble  matter  is  usually  more  or  less  opaque. 
For  microscopical  examination  a few  ounces  should  be  set  aside  in 
a conical  test-glass  for  an  hour  or  two,  the  clear  supernatent  urine 
poured  off  from  the  sediment  as  far  as  possible,  a small  drop  of  the 
residue  placed  on  a slip  of  glass  and  covered  with  a piece  of  thin 
glass  and  examined  under  the  microscope  with  different  magnifying- 
powers. 

SI 


^ 434 


MORBID  URINE. 


The  respective  appearances  of  the  various  crystalline  and  organized 
matteVs  are  given  in  the  following  figures,  which  were  drawn  by 
mv  friend  K B.  Brady,  F.L.S.,  from  natural  specimens  (as  seen 
wfth  a two-third  inchob  ective  and  No.  1 eye-piece,  z.  e.,  magnified 
60  diaLters)  in  the  collections  of  St.  Bartholomew's  Hospital, 
Dr.  Sedgwick,  W.  W.  Stoddart,  F.C.S.,  Mr.  M addington,  and  the 

Uric  Acid  occurs  in  many  forms,  most  of  which  are  given  in  the 
first  two  figures.  Flat,  more  or  less  oval  crystals,  sometimes  attached 


to  each  other,  their  outline  then  resembling  an  8,  a cross,  or  a star, 
are  common.  Single  and  grouped  quadratic  prising  rJm  urTe 
cula  and  crystals  recalling  dumb-bells  are  met  with.  From  urine 
acidulated  by  hydrochloric  acid,  square  crystals,  two  opposite  sides 
smooth  and  two  jagged,  are  generally  deposited  : acidulated  by  acetic 

smootnanuuvoj  = acid  more  typical  forms  are  ob- 


) 


tained.  A drop  of  solution  of 
potash  or  soda  placed  on  a glass 
slip  will  dissolve  a deposit  of 
uric  acid,  a drop  of  any  acid  re- 
precipitating it  in  minute  but 
characteristic  crystals. 

Cystin  is  very  rarely  met  with 
as  a urinary  deposit ; that  from 
which  the  figure  was  taken  was 
found  in  the  urine  of  a patient 
in  St.  Bartholomew’s  Hospital. 
Lamellm  of  cystin  always  as- 
sume an  hexagonal  character ; 
but  the  angles  are  sometimes  ill 
defined  and  the  plates  super- 
posed : in  the  latter  case,  a drop 
of  solution  of  ammonia  placed 


on  the  glass  at  once  dissolves  the  deposit,  well-marked  six-sided  crys- 
tals appearing  as  the  drop  dries  up. 


URINARY  SEDIMENTS. 


435 


Triple  Phosphate  (phosphate  of  magnesium  and  ammonium)  is 
deposited  as  soon  as  urine  becomes  alkaline,  the  ammoniacal  constitu- 
ent being  furnished  by  the  de- 
composition of  urea.  It  occurs 
in  large  prismatic  crystals,  form- 
ing a beautiful  object  when 
viewed  by  polarized  light — 
sometimes  also  in  ragged  stel- 
late or  arborescent  crystals,  re- 
sembling those  of  snow.  Both 
forms  may  be  artificially  pre- 
pared by  adding  a small  lump 
of  carbonate  of  ammonium  to  a 
few  ounces  of  urine  set  aside  in 
a test-glass. 

Amorphous  deposits  are 
either  earthy  phosphates  (a 
mixture  of  phosphates  of  mag- 
nesium and  calcium)  or  urates 
(of  calcium,  magnesium,  ammo- 
nium, potassium,  or  sodium — chiefly  the  latter).  They  may  be  dis- 
tinguished by  the  action  of  a drop  of  acetic  acid  placed  near  the 
sediment  on  the  glass  slip,  the  effect  being  watched  under  the  micro- 
scope ; phosphates  dissolve,  while  urates  gradually  assume  character- 
istic forms  of  uric  acid.  Urates  redissolve  when  warmed  with  the 
supernatant  urine. 

Urates  of  Sodium  and  Magnesium.,  though  generally  amorphous, 
occasionally  take  a crystalline  form — bundles  or  tufts  of  small  needles 
— as  shown  in  the  cut. 

Oxalate  of  UaZcmm  commonly  occurs  in  octahedra  requiring  high 
magnifying  power  for  their  detection.  The  crystals  are  easily  over- 
looked if  other  matters  are  pre- 
sent, but  are  more  distinctly  seen 
after  phosphates  have  been  re- 
moved by  acetic  acid.  In  certain 
aspects  the  smaller  crystals  look 
like  square  plates  traversed  by 
a cross.  A dumb-bell  form  of 
this  deposit  is  also  sometimes 
seen,  resembling  certain  forms 
of  uric  acid  and  the  coalescing 
spherules  of  a much  rarer  sedi- 
ment— carbonate  of  calcium. 

Oxalate  of  calcium  is  insoluble 
in  acetic  but  soluble  in  hydro- 
chloric acid.  The  octahedra  are 
frequently  met  with  in  the  urine 
of  persons  who  have  partaken 
of  garden  rhubarb  ; the  crystals 
may  often  be  deposited  artificially  (according  to  Waddington,)  by 
dropping  a fragment  of  oxalic  acid  into  several  ounces  of  urine  and 
setting  aside  for  several  hours. 


Urates,  a,  of  Sodium,  b,  of  Magnesium. 
Oxalate  of  Calcium. 


436 


MORBID  URINE. 


Carbonate  of  Calcium  is  rarely  found  in  the  urine  of  man,  but 
frequently  in  that  of  the  horse  and  other  herbivorous  animals. 
Human  urine  containing  carbonate  of  calcium  often  reddens  litmus 
paper;  and  it  is  only  after  the  removal,  on  standing,  of  the  excess  of 
carbonic  acid  that  the  salt  is  deposited.  It  consists  of  minute  sphe- 
rules, varying  in  size,  the  smaller  ones  often  in  process  of  coalescence. 
The  dumb-bell  form  thus  produced  is  easily  distinguished  from  similar 

groups  of  uric  acid  or  oxalate  of 
calcium  by  showing  a black  cross 
in  each  spherule  when  viewed  by 
polarized  light.  Acetic  acid  dis- 
solves carbonate  of  calcium,  libe- 
rating carbonic  acid  gas,  with 
visible  effervescence  (under  the 
microscope)  if  the  slide  has  been 
previously  warmed  and  a group 
of  crystals  be  attacked. 

Hippuric  Acid. — The  pointed 
rhombic  prisms  and  acicular  crys- 
tals are  characteristic,  and  easily 
recognized.  The  broader  crj'stals 
may  possibly  be  mistaken  for 
triple  phosphate,  and  the  nar- 
rower for  certain  forms  of  uric 
acid ; but  insolubility  in  acetic 
acid  distinguishes  them  from  the  former,  and  solubility  in  alcohol 
from  the  latter.  These  tests  may  be  applied  while  the  deposit  is 
under  microscopic  observation.  An  alcoholic  solution  of  hippuric  acid 
evaporated  to  dryness,  and  the  residue  treated  with  water,  gives  a 
solution  from  which  characteristic  crystalline  forms  of  hippuric  acid 
may  be  obtained  on  allowing  a drop  to  dry  upon  a slip  of  glass. 

The  organized  deposits  in  urine  entail  greater  care  in  their  determi- 
nation, and  usually  require  a higher  magnifying  power  for  their 
proper  examination,  than  those  of  crystalline  form.  The  figures 
are  drawn  to  230  diameters.  The  following  notes  will  assist  the 
observer. 

Casts  of  uriniferous  tubuli 
are  fibrinous  masses  of  various 
forms,  and  often  of  considerable 
length — sometimes  delicate  and 
transparent,  occasionally  granu- 
lar, and  often  beset  with  fat- 
globules.  Epithelial  debris  are 
frequently  present  in  urine  in 
the  form  of  nucleated  cells,  regu- 
lar and  oval  when  full,  but  angu- 
lar and  unsymmetrical  when  ])ar- 
tially  emptied  of  their  contents 
— sometimes  perfect,  but  more 
frequently  a good  deal  broken 
up. 


URINARY  SEDIMENTS. 


437 


Blood  is  easily  recognized.  Urine  containing  it  is  high-colored, 
and  the  corpuscles  appear  under  the  microscope  as  reddish  circular 
disks,  either  single  or  laid  to- 
gether in  strings  resembling 
piles  of  coin.  Their  color  and 
somewhat  smaller  size  serve  to 
distinguish  them  from  pus-cor- 
puscles. In  doubtful  cases  a 
drop  of  blood  from  the  finger 
should  be  diluted  with  water 
and  used  for  comparison.  After 
urine  containing  blood  has  stood 
for  some  time,  the  corpuscles 
lose  their  regular  outline  and 
become  angular.  (See  a in  the 
figure.)  Day,  of  Geelong,  tests 
for  blood  in  urine,  or  in  stains 
on  clothing,  by  adding  a few 
drops  of  a recently  prepared 
alcoholic  solution  of  the  inner 
unoxidized  portions  of  guaiacum  resin  and  then  a small  quantity  of 
Robbins’s  aqueous  or  ethereal  solution  of  peroxide  of  hydrogen,  when 
a blue  color  results.  If  the  stain  is  on  a dark-colored  fabric,  the 
moistened  parts  may  be  pressed  with  white  blotting  paper,  when 
blue  impressions  will  be  obtained.  Contact  with  many  substances 
causes  the  blue  reaction  or  oxidation  of  guaiacum  ; the  peculiarity  of 
blood  is  that  it  does  not  produce  this  effect  unless  peroxide  of  hydro- 
gen or  a similar  antozonic  liquid  is  present.  Bodies  such  as  per- 
manganate of  potassium,  whose  oxygen  is,  apparently,  in  the  form 
of  ozone,  also  gives  rise  to  a blue  color  with  guaiacum ; peroxide  of 
hydrogen  and  other  compounds  whose  oxygen  is  in  the  opposite, 
positive,  or,  according  to  Schdnbein,  antagonistic  condition,  produce 
no  such  effect.  It  would  seem  as  if  blood  or  some  other  constituent 
of  blood  has  the  power  of  converting  positive  into  negative  oxygen, 
and  thus  cause  an  effect  which  negative  oxygen  alone  is  able  to  pro- 
duce ; for  of  all  substances  which,  like  blood,  do  not  alone  cause  guai- 
acum to  become  blue,  blood  is  the  only  one  that  so  affects  antozo- 
nides  (themselves  inactive)  as  to  enable  them  to  act  as  ozonides,  that 
is  to  oxidize  the  guaiacum.  Both  the  venous  and  arterial  fluid  from 
any  red-blooded  animal  will  produce  this  blue  reaction.  Fruit  stains 
are  darkened  by  ammonia,  which  does  not  alter  the  color  of  blood. 
Iron  stains  or  iron-mould  yield  no  color  to  w^ater,  whereas  the  red 
coloring-matter  of  blood  is  soluble  in  water.  The  peroxide  of  hydro- 
gen should  be  free  from  more  than  a trace  of  acid. 

Pus  and  Mucus. — Purulent  urine  deposits,  on  standing,  a light- 
colored  layer,  easily  diffused  through  the  liquid  by  shaking.  Acetic 
acid  does  not  dissolve  the  sediment;  and  solution  of  potash,  of 
official  strength,  converts  it  into  a gelatinous  mass.  Under  the  micro- 
scope, pus-corpuscles  appear  rounded  and  colorless,  rather  larger 
than  blood-disks,  and  somewhat  granular  on  the  surface.  They 
generally  show  minute  nuclei,  which  are  more  distinctly  seen  after 

37* 


438 


MORBID  URINE. 


treatment  with  acetic  acid.  (See  the  portion  of  the  figure  marked  a.) 
Mucus  possesses  no  definite  microscopic  characters,  but  commonly 

has  imbedded  in  it  pus,  epithe- 
lium, and  air-bubbles.  Mucus  is 
coagulated  in  a peculiar  and 
characteristic  manner  by  acetic 
acid : and  this  reaction,  together 
with  the  ropy  appearance  it 
imparts  to  urine,  prevents  its 
being  confounded  with  pus. 
Day’s  test  for  pus  consists  in 
adding  a drop  or  two  of  oxidized 
tincture  of  guaiacum,  to  the 
urine  or  other  liquid,  when  a 
clear  blue  color  is  produced. 
It  is  necessary  to  moisten  dry 
pus  with  water  before  apply- 
ing the  test.  The  test  liquid 
is  made  by  exposing  a saturated 
alcoholic  solution  of  guaiacum 
to  the  air  until  it  has  absorbed  a sufficient  quantity  of  oxygen  to 
give  it  the  property  of  turning  green  when  placed  in  contact  with 
iodide  of  potassium.  Day’s  test  for  mucus  consists  in  the  application, 
first,  of  oxidized  tincture  of  guaiacum,  which  by  itself  undergoes  no 
change  in  the  presence  of  mucus,  and  then  in  the  addition  of  carbolic 
acid  or  creasote,  which  quickly  changes  the  color  of  the  guaiacum  to 
a bright  blue.  Neither  carbolic  acid  nor  creasote  alone  will  render 
guaiacum  blue.  In  testing  for  mucus  on  cloths,  or  when  it  is  mixed 
with  blood,  it  is  necessary  to  use  the  carbolic  acid  pure,  but  when  the 
mucus  is  in  a liquid  state  it  is  better  to  use  carbolic  acid  diluted  with 
alcohol. 

Saliva. — Saliva  is  an  aqueous  fluid  containing  less  than  I per 
cent,  of  solid  matter,  of  which  one- third  is  an  albuminoid  substance, 
termed  pt^alm  (from  rttvsKov,  spittle),  a body  that  has  power  of  con- 
verting starch  into  dextrin  and 
grape-sugar.  Alkaline  salts,  in- 
cluding a trace  of  sulphocyanide 
of  potassium,  and  calcareous 
compounds,  are  also  present. 

Day’s  test  for  saliva  in  urine, 
etc.,  is  similar  to  that  for  mucus, 
with  the  exception  that  the  bine 
reaction  produced  by  the  oxi- 
dized tincture  of  guaiacum  and 
alcoholic  solution  of  carbolic 
acid  is  highly  intensified  by  the 
addition  of  Eobbins’s  aqueous 
or  ethereal  solution  of  peroxide 
of  hydrogen. 

Fatty  matter  occurs  either  as 
minute  globules  partially  dif- 


URINARY  CALCULI. 


439 


fused  through  the  urine  (as  shown  at  a)  or  in  more  intimate  emulsion 
(as  at  h in  the  figure).  When  present  in  larger  quantity,  it  collects 
as  a sort  of  skim  on  the  surface  after  standing. 

Spermatozoa  are  liable  to  escape  notice,  on  account  of  their  small 
size  and  extreme  transparency.  Suspected  urine  should  be  allowed 
to  settle  some  hours  in  a conical  test-glass,  and  the  drop  at  the  bot- 
tom examined  under  a high  power.  The  drawing  shows  their  tad- 
pole-like appearance. 


Sarcina  ventriculi  is  an  alga  of  very  rare  occurrence  in  urine, 
though  not  unfrequent  in  the  matters  vomited  during  certain  diseases 
of  the  stomach.  The  upper  figures  (a)  are  copied  from  Dr.  Thudi- 
chum’s  drawing  (from  urine) ; the  larger  fronds  (&)  are  from  vomited 
matter. 

Extraneous  bodies,  such  as  hair,  wool,  or  fragments  of  feathers, 
are  often  found  in  urinary  deposits ; and  ludicrous  mistakes  have 
been  made  by  observers  not  on  their  guard  in  respect  to  such  casual 
admixtures. 

Examination  of  Ueinary  Calculi. 

The  term  calculus  is  the  diminutive  of  calx,  a lime-  or  chalk-stone. 

Knowledge  of  the  composition  of  a calculus  or  urinary  deposit 
affords  valuable  diagnostic  aid  to  the  physician  ; hence  the  import- 
ance of  a correct  analysis  of  these  substances. 

Nature  of  Calculi. — Urinary  calculi  have  the  same  composition 
as  unorganized  urinary  sediments.  They  consist,  in  short,  of  sedi- 
ments that  have  been  deposited  slowly  within  the  bladder,  particle 
on  particle,  layer  on  layer,  the  several  substances  becoming  so  com- 
pact as  to  be  less  easily  acted  on  by  reagents  than  when  deposited 
after  the  urine  has  been  passed — the  urates  less  readily  soluble  in 
warm  water,  the  calcic  phosphate  insoluble  in  acetic  acid  until  it  has 
been  dissolved  in  hydrochloric  acid  and  reprecipitated  by  an  alkali. 

Preliminary  Treatment. — If  the  calculus  is  whole,  saw  it  in  two 
through  the  centre,  and  notice  whether  it  is  built  up  of  distinct 
layers  or  apparently  consists  of  one  substance.  If  the  latter,  use 
about  a grain  of  the  sawdust  for  the  analysis ; if  the  former,  carefully 


440 


MORBID  URINE. 


scrape  off  portions  of  each  layer,  and  examine  them  separately.  If 
the  calculus  is  in  fragments,  select  fair  specimens  of  about  half  a 
grain  or  a grain  each,  and  reduce  to  a fine  powder  by  placing  on  a 
hard  surface  and  crushing  under  the  blade  of  a knife. 

Analysis, — Comnaence  the  analysis  by*  heating  a portion 
about  the  size  of  a pin’s  head,  on  platinum  foil,  in  order  to 
ascertain  whether  organic  matter,  inorganic  matter,  or  both, 
are  present.  If  both,  the  ash  is  examined  for  inorganic  sub- 
stances, and  a fresh  portion  of  the  calculus  for  uric  acid 
by  the  murexid  test.  (In  the  absence  of  uric  acid  an}" 
slight  charring  may  be  considered  to  be  due  to  indefinite 
animal  matter.)  If  composed  of  organic  matter  only,  the 
calculus  will  in  nearly  all  cases  be  uric  acid,  the  indication 
being  confirmed  by  applying  the  murexid  test  in  a watch- 
glass  to  another  fragment,  half  the  size  of  a small  pin’s 
head.  If  organic  only,  the  ash  on  the  platinum  foil  may 
be  examined  for  phosphates,  and  a separate  portion  of 
the  calculus  for  oxalates.  Even  a single  drop  of  liquid  ob- 
tained in  any  of  these  experiments  maybe  filtered  by  placing 
it  on  a filter  not  larger  than  a sixpence  and  previously  moist- 
ened with  water,  and  adding  three  or  four  drops  of  water 
one  after  the  other  as  each  passes  through  the  paper.  If 
the  calculus  is  suspected  to  contain  more  than  one  sub- 
stance, boil  about  half  a grain  of  the  powder  in  half  a test- 
tubeful  of  distilled  water  for  a few  minutes  and  pour  it  on 
a small  filter;  then  proceed  according  to  the  following 
Table 


Insoluble. 

Phosphates,  oxalates  of  calcium,  and  free 
uric  acid. 

Boil  with  two  or  three  drops  of  hydrochloric 
acid  and  filter. 

Soluble. 

Urates. 

These  will  pro- 
, bably  be  redepos- 
ited as  the  solu- 
tion cools.  Small 

Insoluble. 

Uric  acid. 
Apply  the 
murexid 
test 

(p.  320). 

Soluble. 

Phosphates  and  oxalate  of 
calcium. 

Add  excess  of  ammonia,  and  then 
excess  of  acetic  acid  ; filter. 

quantities  may  be 
detected  by  eva- 
porating the  solu- 
tion to  dryness. 
They  are  tested 
for  ammonium,  so- 
dium, calcium,  and 

Insoluble. 

Soluble. 

the  uric  radical  by 
the  appropriate  re- 

Oxalate of 

Phosphates. 

agents. 

calcium. 

They  may  be  repre- 
cipitated by  ammonia. 

/ 


QUESTIONS  AND  EXERCISES. 


441 


Varieties  of  Calculi. — Calculi  composed  entirely  of  uric  acid  are 
common ; a minute  portion  heated  on  platinum  foil  chars,  burns,  and 
leaves  scarcely  a trace  of  ash.  The  phosphates  frequently  occur 
together,  forming  what  is  known  as  the  fusible  calculus,  from  the 
readiness  with  which  a fragment  aggregates,  and  even  fuses  to  a 
bead,  when  heated  on  a loop  of  platinum  wire  in  the  blowpipe-flame. 
The  phosphates  may,  if  necessary,  be  further  examined  by  the  method 
described  in  connection  with  urinary  deposits.  Oxalate  of  calcium 
often  occurs  alone,  forming  a dark-colored  calculus  having  a very 
rough  surface,  hence  termed  the  mulberry  calculus.  Smaller  calculi 
of  the  same  substance  are  called,  from  their  appearance,  hempseed 
calculi.  Calculi  of  cystin  are  rarely  met  with.  Xaviliin  (from 
xanthos,  yellow,  in  allusion  to  the  color  it  yields  with  nitric 
acid)  still  less  often  occurs  as  a calculus.  The  earthy  concretions,  or 
chalk-stones,  which  frequently  form  in  the  joints  of  gouty  persons, 
are  composed  chiefly  of  urates,  the  sodium  salt  being  that  most  com- 
monly met  with.  Gall-stones  or  biliary  calcidi,  occasionally  form 
in  the  gall-bladder:  they  contain  cholesterin  (from  chole,  bile, 
and  (jrfpfoj,  stereos,  solid),  a fatty  substance  of  alcoholoid  constitution, 
soluble  in  rectifled  spirit  or  ether,  and  crystallizing  from  such  solu- 
tions in  well-defined,  square,  scaly  crystals.  Phosphatic  and  other 
calculi  of  many  pounds  weight  are  often  found  in  the  stomach  and 
larger  intestines  of  animals. 


QUESTIONS  AND  EXERCISES. 

895.  In  breathing,  how  much  carbon  (in  the  form  of  carbonic  acid 
gas)  is  exhaled  from  the  lungs  every  24  hours  ? 

896.  How  may  the  presence  of  carbonic  acid  gas  in  expired  air  be 
demonstrated  ? 

897.  Mention  an  experiment  showing  the  escape  of  moisture  from 
the  lungs  during  breathing. 

898.  State  the  method  of  testing  for  albumen  in  urine. 

899.  Give  the  tests  for  sugar  in  urine. 

900.  What  is  the  average  composition  of  healthy  urine  ? 

901.  Give  the  tests  for  urea. 

902.  Write  the  rational  formulae  of  some  compound  ureas  in  which 
methyl  or  ethyl  displace  hydrogen. 

903.  Describe  an  artificial  process  for  the  production  of  urea,  giving 
equations. 

904.  Sketch  out  a plan  for  the  chemical  examination  of  urinary 
sediments. 

905.  A deposit  is  insoluble  in  the  supernatant  urine  or  in  acetic 
acid  ; of  what  substances  may  it  consist  ? . 

906.  Which  compounds  are  indicated  when  a deposit  redissolves 
on  warming  it  with  the  supernatant  urine  ? 

907.  Name  the  salts  insoluble  in  warmed  urine  but  dissolved  on  the 
addition  of  acetic  acid. 


442  OFFICINAL  GALENICAL  PREPARATIONS. 


908.  Mention  the  chemical  characters  of  cystin.  At  what  stage 
of  analysis  would  it  be  recognized? 

909.  Describe  the  microscopical  appearance  of  the  following  urin- 
ary deposits : — ^ 


Uric  Acid. 

Cystin. 

Triple  phosphate. 
Earthy  phosphates. 
Urates. 

Oxalate  of  Calcium. 
Carbonate  of  Calcium. 
Hippuric  Acid. 


Tube-casts. 
Epithelial  debris. 
Blood. 

Pus. 

Mucus. 

Fat. 


Spermatozoa. 

Sarcina. 


Extraneous  Bodies. 


910.  How  are  Day’s  tests  for  blood,  pus,  and  saliva  applied  ? 

911.  What  is  the  general,  physical,  and  chemical  nature  of  urinary 
calculi  ? 

912.  How  are  urinary  calculi  prepared  for  chemical  examination  ? 

913.  Draw  out  a chart  for  the  chemical  examination  of  urinary 
calculi. 

914.  Why  is  the  fusible  calculus”  so  called,  and  what  is  its  com- 
position ? 

915.  State  the  characters  of  “ mulberry”  and  “ hempseed”  calculi. 

916.  What  are  the  “ chalk-stones”  of  gout  and  “ gall-stones”  or 

biliary  calculi  ?” 


THE  GALENICAL  PREPARATIONS  OF 
THE  BRITISH  PHARMACOPCEIA. 


The  preparation  of  Confections,  Decoctions,  Enemas,  j 
Extracts,  Glycerines,  Infusions,  Inhalations,  Juices,  Lini-  [ 
ments.  Lozenges,  Mixtures,  Ointments,  Pills,  Plasters,  i 
Poultices,  Powders,  Spirits,  Suppositories,  Syrups,  Tine-  | 
tures,  and  Wines,  includes  a number  of  mechanical  rather  | 
than  chemical  operations,  and  belongs  to  the  domain  of  | 
pure  Pharmacy.  The  medical  or  pharmaceutical  pupil  will  ! 
have  had  ample  opportunity  of  practicall}^  studying  these  i 
compounds  before  working  at  experimental  chemistry,  and  , 
will^pr^ably  have  prepared  many  of  them  according  to 
tlre'^directions  of  the  Pharmacopoeia;  if  not,  he  is  referred  : 
to  the  pages  of  the  last  edition  of  that  work  for  details.  i 
Among  the  extracts  of  the  British  Pharmacopoeia,  how-  | 
ever,  there  are  five  (namely,  those  of  Aconite,  Belladonna, 
Hemlock,  Henbane,  and  Lettuce)  which  are  not  simply  i 
evaporated  infusions,  decoctions,  or  tinctures,  like  most  : 


OFFICINAL  GALENICAL  PREPARATIONS.  443 


others,  but  are  evaporated  juices  from  which  vegetable 
albumen,  the  supposed  source  of  fermentation  and  decay, 
has  been  removed,  and  chlorophyll  (the  green  coloring- 
matter  of  plant-juice)  retained  practically  unimpaired  in 
tint.  In  order  that  attention  may  be  concentrated  on  the 
process  by  which  these  are  prepared,  rather  than  on  the 
extracts  themselves,  it  is  advisable  to  make  an  extract  of 
some  ordinary  green  vegetable,  such  as  cabbage  or  turnip- 
tops.  Bruise  the  green  leaves  of  a good-sized  cabbage  in 
a mortar,  and  press  out  the  juice;  heat  it  gradually  to 
130°,  and  remove  the  green  flocks  of  chlorophyll  which 
separate,  by  filtration  through  calico.  When  the  liquor 
has  all  passed  through  the  filter,  set  the  chlorophyll  aside 
for  a time,  heat  the  strained  liquor  to  200°  to  coagulate 
albumen  ; remove  the  latter  by  filtration  and  throw  away ; 
evaporate  the  filtrate  by  a water-bath  to  the  consistence 
of  thin  syrup  ; then  add  to  it  the  chlorophyll,  and,  stirring 
the  whole  together  assiduously,  continue  the  evaporation 
at  a temperature  not  exceeding  140°,  until  the  extract  is 
of  a suitable  consistence  for  forming  pills.  A higher  tem- 
perature than  that  indicated  would  cause  the  alteration  of 
the  chlorophyll  to  a dark-brown  substance,  the  extraet  no 
longer  having  the  green  tint  which  custom  and  the  British 
Pharmacopoeia  demand. 


QUESTIONS  AND  EXEKCISES. 

917.  Enumerate  the  different  classes  of  official  galenical  prepara- 
tions. 

918.  Describe  the  general  process  for  the  preparation  of  green 
extracts : — 

Aconite.  Hemlock. 

Belladonna.  Henbane. 

Lettuce. 

919.  Why  is  vegetable  albumen  excluded  in  the  preparation  of 
green  extracts  ? 

920.  How  may  chlorophyll  be  removed  from  vegetable  Mces^;attd 
again  be  introduced  into  their  evaporated  residues,  withouvde^tro^^ 
ing  its  color. 

921.  For  what  reason  is  exposure  of  chlorophyll  to  heat  avoided 
in  the  manufacture  of  green  extracts  ? 


444  OFFICINAL  CHEMICAL  PREPARATIONS. 


THE  CHEMICAL  PREPARATIONS  OF 
THE  PHARMACOPCEIAS. 

The  process  by  which  every  official  chemical  substance 
is  prepared  has  already  been  described,  and  the  strict 
chemical  character  of  the  processes  illustrated  by  experi- 
ments and  explained  by  aid  of  equations.  Should  the 
reader,  in  addition,  desire  an  intimate  acquaintance  with 
those  details  of  manipulation  on  which  the  successful  and 
economic  manufacture  of  chemical  substances  depends,  he 
is  advised  to  prepare,  if  he  has  not  done  so  already,  a few 
ounces  of  each  of  the  salts  mentioned  in  the  Pharmacopoeias 
or  commonly  used  in  Pharmacy.  An  additional  guide  in 
these  operations  will  be  the  Pharmacopoeia  itself. 

The  production  of  many  chemical  and  galenical  sub- 
stances on  a commerical  scale  can  only  be  successfully  car- 
ried on  in  manufacturing-laboratories  and  with  some  knowl- 
edge of  the  circumstances  of  supply  and  demand,  value 
of  raw  material,  and  of  by-products.  Commercial  Chem- 
istry and  Pharmacy,  however,  can  best  hope  for  success 
when  founded  on  the  working  out  of  abstract  principles. 
The  problem  of  manufacturing-success  is  solved  with  cer- 
tainty by  wisely  applied  science. 


Memorandum, — The  next  subjects  of  experimental  study 
will  be  determined  by  the  nature  of  the  student’s  future 
pursuits.  In  most  cases  the  operations  of  quantitative 
analysis  will  engage  attention.  These  should  be  of  a volu- 
metric and  gravimetric  character ; for  details  concerning 
them  see  the  following  pages. 


QUANTITATIVE  ANALYSIS. 


445 


QUANTITATIVE  ANALYSIS. 

INTEODUCTORY  REMARKS. 

General  Principles. — The  proportions  in  which  chemical  substances 
unite  with  each  other  in  forming  compounds  are  definite  and  invari- 
able (p.  41).  Quantitative  analysis  is  based  on  this  law.  When, 
for  example,  aqueous  solutions  of  a salt  of  silver  and  a chloride  are 
mixed,  a white  curdy  precipitate  is  produced  containing  chlorine  and 
silver  in  atomic  proportions,  that  is,  35.5  parts  of  chlorine  to  108  of 
silver.  No  matter  what  the  chloride  or  what  the  salt  of  silver,  the 
resulting  chloride  of  silver  is  invariable  in  composition.  The  formula 
AgOi  is  a convenient  picture  of  this  compound  in  these  proportions. 
The  weight  of  a definite  compound  being  given,  therefore,  the  pro- 
portional amounts  of  its  constituents  can  be  ascertained  by  simple 
calculation.  Thus,  for  instance,  8.53  parts  of  chloride  of  silver  con- 
tain 2.11  parts  of  chlorine  and  6.42  of  silver : for  if  143.5  (the  molec- 
ular weight)  of  chloride  of  silver  contain  35.5  (the  atomic  weight) 
of  chlorine,  8.53  of  chloride  of  silver  will  be  found  to  contain  2.11  of 
chlorine : — 

143.5  : 35.5  : : 8.53  : ic 

8.53 
1.065 
17.75 

284.0 

143.5)302.815(2.11 

287.0 
15.81 
14.35 

1.465 

1.435  x = 2.ll. 

And  if  143.5  of  chloride  of  silver  contain  108  of  silver,  8.53  of  chlo- 
ride of  silver  will  contain  6.42  of  silver.  To  ascertain,  for  example, 
the  amount  of  silver  in  a substance,  containing,  say,  nitrate  of  silver, 
all  that  is  necessary  is  to  take  a weighed  quantity  of  the  substance, 
dissolve  it,  precipitate  the  whole  of  the  silver  by  adding  hydrochloric 
acid  or  other  chloride  till  no  more  chloride  of  silver  falls,  collect  the 
precipitate  on  a filter,  wash,  dry,  and  weigh.  The  amount  of  silver 
in  the  dried  chloride,  ascertained  by  calculation,  is  the  amount  of 
silver  in  the  quantity  of  substance  on  which  the  operation  was  con- 
ducted ; a rule-of-three  sum  gives  the  quantity  per  cent. — the  form 
in  which  the  results  of  quantitative  analysis  are  usually  staled. 
38 


446 


QUANTITATIVE  ANALYSIS. 


Occasionally  a constituent  of  a substance  admits  of  being  isolated 
and  weighed  in  the  uncombined  state.  Thus  the  amount  of  mercury 
in  a substance  may  be  determined  by  separating  and  weighing  the 
mercury  in  the  metallic  condition  ; if  occurring  as  calomel  (HgCl)  or 
corrosive  sublimate  (HgCl.^),  the  proportion  of  chlorine  may  then  be 
ascertained  by  calculation  (Hg  = 200;  Cl  = 35.5). 

Nature  of  Gravimetric  Quantitative  Analysis. — As  above  stated, 
a body  may  be  isolated  and  iveighed  and  its  quantity  thus  ascertained ; 
or  it  may  be  separated  and  weighed  in  combination  with  another 
body  whose  combining  proportion  is  well  known  ; this  is  quantitative 
analysis  by  the  gravimetric  method. 

Nature  of  Volumetric  Quantitative  Analysis. — Quantitative  an- 
alysis by  the  volumetric  method  consists  in  noting  the  volume  of  a 
liquid  required  to  be  added  to  the  substance  under  examination  before 
a given  effect  is  produced.  Thus,  for  instance,  a solution  of  nitrate  of 
silver  of  known  strength  may  be  used  in  experimentally  ascertain- 
ing an  unknown  amount  of  chlorine  in  any  substance.  The  silver 
solution  is  added  to  a solution  of  a definite  quantity  of  the  substance 
until  flocks  of  chloride  of  silver  cease  to  be  precipitated : every  108  | 
parts  of  silver  added  (or  170  of  nitrate  of  silver:  Ag=108,  N=14 
03=48 ; total  170)  indicates  the  presence  of  35.5  of  chlorine,  or  an 
equivalent  quantity  of  any  chloride.  The  preparation  of  standard 
solutions,  such  as  that  of  nitrate  of  silver,  to  which  allusion  is  here  \ 
made,  requires  considerable  care  ; but  when  made,  certain  analyses  | 
can  be  executed  with  far  more  rapidity  and  ease  than  by  gravimetric  | 
processes.  ; 

Note. — The  quantitative  analysis  of  solids  and  liquids  often  in-  i 
volves  determinations  of  temperature  and  specific  gravity.  These  i 
processes  will  now  be  explained,  after  which  an  outline  of  volumetric  | 
and  gravimetric  quantitative  analysis  will  be  given.  The  scope  of  : 
this  work  precludes  any  attempt  to  describe  all  the  little  mechanical  ! 

details  observed  by  quantitative  analysts ; essential  operations,  how-  1 
ever,  are  so  fully  treated  that  expert  manipulators  will  meet  with  i 
little  difficulty.  I 

Measurement  of  Atmospheric  Pressure.  I 

The  Barometer. — The  analysis  of  gases  and  vapors  involves,  also, 
determinations  of  the  varying  pressure  of  the  atmosphere  as  indi-  ! 
cated  by  the  barometer  (from  jSapoj,  bar  os,  weight,  and  me-  > 

tron,  measure).  The  ordinary  mercurial  barometer  is  a glass  tube 
33  or  34  inches  long,  closed  at  one  end,  filled  with  mercury,  and  in- 
verted in  a small  cistern  or  cup  of  mercury.  The  mercury  remains 
in  the  tube  owing  to  the  weight  or  pressure  of  the  atmosphere  on  the  i 
exposed  surface  of  the  liquid,  the  average  height  of  the  column 
being  nearly  30  inches.  In  the  popular  form  of  the  instrument,  the  i 
wheel-barometer,  the  cistern  is  formed  by  a recurvature  of  the  tube ; \ 
on  the  exposed  surface  of  the  mercury  a float  is  placed,  from  which  ; 

• a thread  passes  over  a pulley  and  moves  an  index  whenever  the  i 
column  of  mercury  ilses  or  falls.  As  supplied  to  the  public  these  i 
barometers  are  usually  inclosed  in  ornamental  frames  with  thermo-  ; 


MEASUREMENT  OF  TEMPERATURE. 


U1 


meters  attached.  In  the  wheel-barometer  the  glass  tube  and  con- 
tained column  of  mercury  are  altogether  inclosed,  the  index  alone 
being  visible.  In  the  other  variety  the  upper  end  of  the  glass  tube 
and  mercurial  column  are  exposed  and  the  height  of  the  mercury  is 
ascertained  by  direct  observation. 

The  aneroid  barometer  (from  a,  a,  ivithout,  and  neros,  fluid) 
consists  of  a small,  shallow,  vacuous  metal-drum,  the  sides  of  which 
approach  each  other  when  an  increase  of  atmospheric  pressure  occurs, 
their  elasticity  enabling  them  to  recede  toward  their  former  position 
on  a decrease  of  pressure.  This  motion  is  so  multiplied  and  altered 
in  direction  by  levers,  etc.,  as  to  act  on  a hand  traversing  a plate  on 
which  is  marked  numbers  corresponding  with  those  showing  the 
height  of  the  mercurial  column  of  the  ordinary  barometer  by  which 
the  aneroid  was  adjusted.  The  Bourdon  barometer  (from  the  name 
of  the  inventor)  is  a modified  aneroid,  containing,  in  the  place  of  the 
round  metal  box,  a flattened  vacuous  tube  of  metal,  bent  nearly  to 
a circle.  These  barometers  are  also  useful  for  measuring  the  pres- 
sure in  steam-boilers,  etc.  Under  the  name  of  'pressure-gauges  they 
are  sold  to  indicate  pressures  of  500  pounds  and  upwards  per  square 
inch.  From  their  portability  (they  can  be  made  of  1 to  2 inches  in 
diameter  and  I inch  thick)  they  are  excellent  companions  for  trav- 
ellers wishing  to  know  the  heights  of  hills,  mountains,  and  other 
elevations. 

For  further  information  concerning  the  influence  of  pressure  on 
the  volume  of  a gas  or  vapor  see  page  469 ; and  for  descriptions  of 
the  methods  of  analyzing  gases,  refer  to  Ganot^s  Physics”  (trans- 
lated by  Atkinson),  Miller’s  “Chemical  Physics,”  and  “Analysis  of 
Gases”  in  Watts’s  “ Dictionary  of  Chemistry.” 


MEASUREMENT  OF  TEMPERATURE. 

General  Principles. — As  a rule,  all  bodies  expand  on  the  addi- 
tion, and  contract  on  the  abstraction  of  heat,  the  alteration  in 
volume  being  constant  and  regular  for  equal  increments  or  decre- 
ments of  temperature.  The  extent  of  this  alteration  in  a given  sub- 
stance, expressed  in  parts  or  degrees,  constitutes  the  usual  method 
of  intelligibly  stating,  with  accuracy,  precision,  and  minuteness,  a 
particular  condition  of  warmth  or  temperature,  that  is,  of  sensible 
heat.  The  substance  commonly  employed  for  this  purpose  is  mer- 
cury, the  chief  advantages  of  which  are  that  it  will  bear  a high  tem- 
perature without  boiling,  a low  temperature  without  freezing,  does 
not  adhere  to  glass  to  a sufficient  extent  to  “ wet”  the  sides  of  any 
tube  in  which  it  may  be  inclosed,  and,  from  its  good  conducting- 
power  for  heat,  responds  rapidly  to  changes  of  ^temperature.  Plati- 
num, earthenware,  alcohol,  and  air  are  also  occasionally  used  for 
thermometric  purposes. 

The  Thermometer. — The  construction  of  an  accurate 
thermometer  is  a matter  of  great  difficulty  ; but  the  follow- 
ing are  the  leading  steps  in  the  operation.  Select  a piece 


448 


QUANTITATIVE  ANALYSIS. 


of  glass  tubing  having  a fine  capillary  (capillus^  a hair) 
bore,  and  about  a foot  long.;  heat  one  extremity  in  the 
blowjiip e-flame  until  the  orifice  closes,  and  the  glass  is  sufii- 
cientl}^  soft  to  admit  of  a bulb  being  blown  ; heat  the  bulb 
to  expel  air,  immediately  plunging  the  open  extremity  of 
the  tube  into  mercury  ; the  bulb  having  cooled,  and  some 
mercury  having  entered  and  taken  the  place  of  expelled  air, 
again  heat  the  bulb  and  tube  until  the  mercury  boils  and 
its  vapor  escapes  through  the  bore  of  the  tube ; again 
plunge  the  extremity  under  mercury,  which  will  probably 
now  completely  fill  the  bulb  and  tube.  When  cold  the 
bulb  is  placed  in  melting  ice.  The  top  of  the  column  of 
mercury  in  the  capillary  tube  should  then  be  within  an  inch 
or  two  of  the  bulb ; if  higher,  some  of  the  mercury  must 
be  expelled  by  heat ; if  lower,  more  metal  must  be  intro- 
duced as  before.  The  tube  is  now  heated  near  the  open  end 
and  a portion  drawn  out,  until  the  diameter  is  reduced  to 
about  one-tenth.  The  bulb  is  next  warmed  until  the  mer- 
curial column  rises  above  the  constricted  part  of  the  tube^ 
which  is  then  rapidly  fused  in  the  blowpipe-flame,  and  the 
extremity  of  the  tube  removed. 

The  instrument  is  now  ready  for  graduation.  The  bulb 
is  placed  in  boiling-water  (a  medium  having,  caeteris  paid- 
bu8^  an  invariable  temperature),  and,  when  the  position  of 
the  top  of  the  mercurial  column  is  constant,  a mark  is 
made  on  the  tube  by  a scratching  diamond  or  a file.  This 
operation  is  repeated  with  melting  ice  (also  a medium 
having  an  invariable  temperature).  The  space  between 
these  two  marks  is  divided  into  a certain  number  of  inter- 
vals termed  degrees.  Unfortunately  this  number  is  not 
uniform  in  all  countries  : in  England  it  is  180,  as  proposed 
by  Fahrenheit;  in  France  100,  as  proposed  by  Celsius 
(the  Centigrade  scale),  a number  generally  adopted  by  sci- 
entific men  ; in  some  parts  of  the  Continent  the  divisions 
ai*e  80  for  the  same  interval,  as  suggested  by  Ecaumur. 
Whichever  be  the  number  selected,  similar  markings  should 
be  continued  beyond  tlie  boiling-  and  freezing-points  as 
far  as  the  length  of  the  stem  admits. 

Thermometric  Scales. — On  tlie  Centigrade  and  Iteaumur  scales 
the  freezing  point  of  water  is  made  zero,  and  the  boiling  point  100 
and  80  respectively ; on  the  Fahrenheit  scale  the  zero  is  placed  32 
degrees  below  the  congealing-point  of  water,  the  boiling-point  of 
which  becomes,  consequently,  212.  Even  on  the  Fahrenheit  system 
temperatures  below  the  freezing-point  of  water  are  often  spoken  of 
as  “ degrees  of  frost ;”  thus  1 0 degrees  as  marked  on  the  thermom- 


THERMO  METRIC  SCALES. 


449 


eter  would  be  regarded  as  “ 13  degrees  of  frost.’*  It  is  to  be  regret- 
ted that  the  freezing-point  of  water  is  not  universally  regarded  as 
the  zero-point,  and  the  number  of  intervals  between  that  and  the 
boiling-point  everywhere  the  same. 

The  degrees  of  one  scale  are  easily  converted  into  those  of 
another,  if  their  relations  be  remembered,  namely:  180  (F.),  100 
(C.),  80  (R.) ; or  18,  10,  and  8 ; or,  best,  9,  5,  and  4. 

Formulae  for  the  conversion  of  degrees  of  one  thermometric 
scale  into  those  of  another, 

F=Fahrenheit.  C—Centigrade. 

R=Reaumur.  D=The  observed  degree. 

If  above  the  freezing-point  of  water  (32^  F ; 0^  C ; 0^  R), 

FintoC (D— 32)-4-9x5. 

F “ R 32)-^9x4. 

C F R-t-  5 X 94-32. 

R “ F D-4-  4 X94-32. 

If  below  freezing,  but  above  0^  F ( — 17^.77  C;  — 14^.22  R), 

F into  0 — (32 — D)-^9x5. 

F “ R -_(32— D)-^9x4. 

0 ‘‘  F 32— (D~.5x9). 

R F 32— (D-~4x9). 

If  below  OO  F (—170.77  C ; —140.22  R). 

F into  0 _(D-t-32)-^9  x5. 

F “ R _(D-l-32)-f-9  X4. 

C “ F ._(D-^  5 x9)— 32. 

R F -_(D-i-  4 x9)— 22. 

For  all  degrees  : — 

C into  R D-f-5x4. 

R C D-4-4X5. 

In  ascertaining  the  temperature  of  a liquid,^  the  bulb  of 
a thermometer  is  simply  inserted  and  the  degree  noted. 
In  determining  the  boiling-point,  also,  the  bulb  is  inserted 
ill  the  liquid,  if  a pure  substance.  In  taking  the  boiling- 
point  of  a. liquid  which  is  being  distilled  from  a mixture, 
the  bulb  of  the  thermometer  should  be  near  to  but  not 
beneath  the  surface. 

The  following  are  the  boiling  points  of  a few  substances 


met  with  in  pharmacy  : — 

Centigrade.  Fahrenheit. 

Alcohol,  absolute 78.3  173 

“ 84  per  cent 79.5  175 

“ 49  per  cent,  (proof  spirit)  . . 81.4  178.5 

amylic  132.2  270 

Benzol 80.6  177 

Bromine 63.0  145.4 

Benzoic  acid 239.0  462 

( -arbolic  acid 187.8  370 


38* 


450 


QUANTITATIVE  ANALYSIS. 


Centigrade.  Fahrenheit. 


C 111  or  0 form 61  142 

Ether  (B.  P.) (below)  40.5  105 

“ pure 35  95 

Mercury  in  vacuo  (as  in  a thermometer)  304  580 

“ in  air  (barom.  at  30  inches)  . . 350  662 

Water  (barom.  at  29.92  inches)  . . . 100  212 

“ ( “ 29.33  “ ) ...  99.5  211 

‘‘  ( “ 28.74  “ ) . . . 99  210 

Saturated  solutions  of — 

Cream  of  tartar 101  214 

Common  salt 106.6  224 

Sal  ammoniac 113.3  236 

Nitrate  of  sodium 119  246 

Acetate  of  sodium 124.4  256 

Chloride  of  calcium 179.4  355 


By  ‘‘  gentle  heat,”  U.  S.  P.,  is  meant  any  temperature  between 
900  and  lOOO  F. 

To  Determine  Melting-points  of  Fat, — Heat  a fragment 
of  the  substance  (spermaceti  or  wax  for  example)  till  it 
liquefies,  and  then  draw  up  a small  portion  into  a thin 
glass  tube,  about  the  size  of  a knitting-needle.  Immerse 
the  tube  in  cold  water  contained  in  a beaker,  and  slowly 
heat  the  vessel  till  the  thin  opaque  cylinder  of  solid  fat 
melts  and  becomes  transparent : a delicate  thermometer 
placed  in  the  water  indicates  the  point  of  change  to  the 
fifth  of  a degree.  Remove  the  source  of  heat,  and  note  | 
the  congealing-point  of  the  substance ; it  will  be  identical  | 
with  or  close  to  the  melting-point.  f 

Pyrometers, — Temperatures  above  the  boiling-point  of  » 
mercuiy  are  determined  by  ascertaining  to  what  extent  a 
bar  of  platinum  or  porcelain  has  elongated.  The  bar  is  f 
inclosed  in  a cavity  of  a suitable  case,  a plug  of  platinum  ii 
or  porcelain  placed  at  one  end  of  the  bar,  and  the  whole 
exposed  in  the  region  whose  temperature  is  to  be  found. 
After  cooling,  the  distance  to  which  the  bar  has  forced  the  , 
plug  along  the  cavity  is  accurately  measured  and  the  cor-  ;! 
responding  degree  of  temperature  noted.  The  value  of 
the  distanc  e is  fixed  for  low  temperatures  by  comparison 
with  a mercurial  thermometer,  and  the  scale  carried  up-  : 
wards  through  intervals  of  equivalent  length.  Such  ther-  .v 
mometers  are  conventionally  distinguished  from  ordinary  j 
instruments  by  the  name  pyrometer  (from  rtvp,  piir,^  fire,  Ji 
and  ^trpoj/,  metron^  measure).  ! 

The  following  mellwg-j^oints  of  olTicial  substances  are  |- 
given  in  the  British  Pharmacopnpia  : — • i 


QUESTIONS  AND  EXERCISES. 


451 


In  degrees  Tn  degrees 
Centigrade.  Fahrenheit. 


Acetic  acid,  glacial 

8.9 

48 

a a 

congeals  at 

I.I 

34 

Benzoic  acid  . . 

120 

248 

Carbolic  acid  . . 

35 

95 

Oil  of  theobroma  . 

50 

122 

Phosphorus  . . 

43.3 

no 

Prepared  lard  . . 

. (about) 

38 

100 

“ suet . . 

39.5 

103 

Spermaceti  . . 

38 

100 

White  wax  . . 

(not  under) 

65.5 

150 

Yellow  wax  . . 

60 

140 

The  order  of  fusibility  of  a few  of  the  metals  is  as  fol- 
lows : — 


Mercury  . . . . , 

In  degrees 
Centigrade. 

In  degrees 
Fahrenheit. 

~ 39 

Potassium  . . . 

. . . . 4-  62.5 

+ 144.5 

Sodium  . . . . , 

. . . . 97.6 

207.7 

Tin 

. . . . 227.8 

442 

Bismuth 

. . . . 264 

507 

Lead 

. . . . 325 

617 

Zinc 

. . . . 411.6 

773 

Antimony  ... 

. . . . G21 

1150 

Silver  . . . . , 

. . . . 1023 

1873 

Copper  . . . . , 

. . . . 1091 

1996 

Gold  .....' 

. . . . 1102 

2016 

Cast  iron  . . . 

. . . . 1530 

2786 

QUESTIONS  AND  EXERCISES. 

922.  On  what  fundamental  laws  are  the  operations  of  quantitative 
analysis  based  ? 

923.  What  is  the  general  nature  of  gravimetric  quantitative 
analysis  ? 

924.  Describe  the  general  principle  of  volumetric  quantitative 
analysis. 

925.  flow  are  variations  in  atmospheric  pressure  quantitatively 
determined  ? 

926.  Explain  the  construction  and  mode  of  action  of  a mercurial 
barometer. 

927.  In  what  respect  does  a wheel-barometer  differ  from  an  instru- 
ment in  which  the  readings  are  taken  from  the  top  of  the  column  of 
mercury  ? 

928.  Describe  the  principle  of  action  of  an  aneroid  barometer. 

929.  On  what  general  principles  are  thermometers  constructed  ? 

930.  What  material  is  employed  in  making  thermometers  ? 


452 


QUANTITATIVE  ANALYSIS. 


931.  AYhy  is  mercury  selected  as  a thermometric  indicator  ? 

232.  Describe  the  manufacture  of  a mercurial  thermometer. 

933.  How  are  thermometers  graduated  ? 

934.  Give  formulae  for  the  conversion  of  the  degrees  of  one  ther- 
mometric  scale  into  those  of  another,  [a)  when  the  temperature  is 
above  the  freezing-point  of  water,  (5)  below  32^  F.  but  above  0°  F., 
and  (c)  below  0°  F. 

935.  Name  the  degree  C.  equivalent  to  60^  F. 

936.  What  degree  C.  is  represented  by  — 4^  F.  ? 

937.  Mention  the  degree  F.  indicated  by  20^  C. 

938.  Convert  100^  R.  into  degrees  C.  and  F. 

939.  State  the  boiling-points  of  alcohol,  chloroform,  ether,  mer- 
cury, and  water  on  either  thermometric  scale. 

940.  Describe  the  details  of  manipulation  in  estimating  the  melt- 
ing-point of  fats. 

941.  In  what  respect  do  pyrometers  differ  from  thermometers  ? 

942.  Mention  the  melting-points  of  glacial  acetic  acid,  oil  of  theo- 
broma,  lard,  suet,  and  wax. 

943.  Give  the  fusing-pomts  of  tin,  lead,  zinc,  copper,  and  cast-iron. 


ESTIMATION  OF  WEIGHT. 

DEFINITIONS. 

All  bodies,  celestial  and  terrestrial,  attract  each  other,  the  amount 
of  attraction  being  in  direct  proportion  to  the  quantity  of  matter  of 
which  they  consist,  and  in  inverse  proportion  to  the  squares  of  their 
distances.  This  is  gravitation.  When  gravitation  in  certain  direc- 
tions is  exactly  counterbalanced  by  gravitation  in  opposite  directions, 
a body  (e.  g.  the  earth)  remains  suspended  in  space.  Such  a body, 
in  relation  to  other  bodies,  has  gravity  but  not  weight.  Weight  is 
the  effect  of  gravity,  being  the  excess  of  gravitation  in  one  direction 
over  and  above  that  exerted  in  the  opposite  direction.  Weight, 
truly,  in  any  terrestrial  substance,  is  the  excess  of  attraction  which 
it  and  the  earth  have  for  each  other  over  and  above  the  attraction 
of  each  in  opposite  directions  by  the  various  heavenly  bodies.  But. 
practically,  the  weight  of  any  terrestrial  substance  is  the  effect  of 
the  attraction  of  the  earth  only.  Specific  weight  is  the  definite  or 
precise  weight  of  a body  in  relation  to  its  bulk  ; it  is  more  usually 
but  not  quite  correctly  termed  specific  gravity — gravity  belonging 
to  the  earth,  not  to  the  substance. 


QUESTIONS. 

944.  What  is  understood  by  gravitation  ? 

945.  State  the  difference  between  weight  and  gravity. 

946.  Mention  a case  in  which  a body  has  gravity  but  no  apparent 
w^eight. 

947.  Practically,  what  causes  the  weight  of  terrestrial  substances  ? 


WEIGHTS  AND  MEASURES. 


453 


Weights  and  Measures. 


The  Balance. — The  balance  used  in  the  quantitative  operations  of 
analytical  chemistry  must  be  accurate  and  sensitive.  The  points  of 
suspension  of  the  beam  and  pans  should  be  polished  steel  or  agate 
knife-edges,  working  on  agate  planes.  It  should  turn  easily  and 
quickly,  without  too  much  oscillation,  to  or  of  a grain,  or 

of  a milligramme,  when  1000  grains,  or  50  or  60  grammes,  are 
placed  in  each  scale.  (Grammes  are  weights  of  the  metric  system, 
a description  of  which  is  given  on  the  next  two  or  three  pages.)  The 
beam  should  be  light  and  strong,  capable  of  supporting  a load  of 
1500  grains  or  100  grammes  ; its  oscillations  are  observed  by  help  of 
a long  index  attached  to  its  centre,  and  continued  downward  for 
some  distance  in  front  of  the  supporting  pillar  of  the  balance.  The 
instrument  should  be  provided  with  screws  for  purposes  of  adjust- 
ment, a mechanical  contrivance  for  supporting  the  beam  above  its 
bearing  when  not  in  use  or  during  the  removal  or  addition  of  weights, 
spirit  levels  to  enable  the  operator  to  give  it  a horizontal  position, 
and  be  inclosed  in  a glass  case  to  protect  from  dust.  It  should  be 
placed  in  a room  the  atmosphere  of  which  is  not  liable  to  be  con- 
taminated by  acid  fumes,  in  a situation  free  from  vibration  ; and  a 
vessel  containing  lumps  of  quicklime  should  be  placed  in  the  case  to 
keep  the  inclosed  air  dry  and  prevent  the  formation  of  rust  on  the 
steel  knife-edges  or  other  parts.  During  weighing,  the  doors  of  the 
balance  should  be  shut,  in  order  that  currents  of  air  may  not  un- 
equally influence  the  pans. 

The  Weights. — These  should  be  preserved  in  a box  having  a sepa- 
rate compartment  for  each.  They  must  not  be  lifted  directly  with 
the  Angers,  but  by  a small  pair  of  forceps.  If  grain-weights,  they 
should  range  from  1000  grs.  to  gr.,  a weight  being  fashioned  of 
gold  wire  to  act  as  a ‘‘  rider”  on  the  divided  beam,  and  thus  indicate 
by  its  position  lOOths  and  lOOOths  of  a grain.  From  to  10  grs. 
the  weights  may  be  of  platinum ; thence  upward  to  1000  grs.  of 
brass.  The  relation  of  the  weights  to  each  other  should  be  decimal. 
Metric  decimal  weights  may  range  from  100  grammes  to  1 gramme, 
of  brass,  and  thence  downward  to  1 centigramme,  of  platinum,  a 
gold  centigramme  rider  being  employed  to  indicate  milligrammes  and 
tenths  of  a milligramme. 

Weights  and  Measures  of  the  TJ.  S.  Pharmacopoeia— The 

weights  and  measures  used  by  physicians  and  apothecaries  in  the 
United  States,  when  prescribing  and  preparing  medicines,  are  the 
following — as  stated  in  the  U.  S.  Pharmacopoeia. 

Wei^its. — These  are  derived  from  the  troy  'pound,  and  are  exhi- 
bited in  the  following  table,  with  their  signs  annexed  : — 


One  pound,  K = 12 

One  ounce,  § = 8 

One  drachm,  ^ = 3 

One  scruple,  9 . . 

One  grain  gr.  . . 


ounces  = 5760  grains, 

drachms  = 480  grains, 

scruples  = 60  grains. 

. . . = 20  grains. 

. . . = 1 grain. 


In  order  to  avoid  the  danger  of  mistakes  from  confounding  the 
troy  and  avoirdupois  pounds,  the  term  pound  is  disused  in  the  for- 


454 


QUANTITATIVE  ANALYSIS. 


TTiiilae  of  the  U.  S.  Pharmacopoeia,  and  the  desired  weight  is  expressed 
in  ounces,  each  containing  four  hundred  and  eighty  grains.  This 
ounce  is  always  printed  troyounce,  to  guard  against  the  error  of  sub- 
stituting for  it  the  avoirdupois  ounce,  consisting  of  four  hundred  and 
thirty-seven  and  a half  grains.  The  drachm  and  scruple  are  also 
disused,  and  replaced  by  their  equivalents  in  grains. 

It  is  highly  important  that  persons  engaged  in  preparing  medi- 
cines should  be  provided  with  troy  weights.  But  those  who  are  not 
so  provided  can  make  their  avoirdupois  weights  available  as  substi- 
tutes for  troy  weights,  by  bearing  in  mind  that  42.5  grains,  added  to 
the  avoirdupois  ounce,  will  make  it  equal  to  the  troy  ounce ; and 
that  1240  grains,  deducted  from  the  avoirdupois  pound,  will  reduce 
it  to  the  troy  pound. 

Measures. — These  are  derived  from  the  wine  gallon,  and  are  given 
in  the  following  table,  with  their  signs  annexed : — 


One  gallon,  0 = 8 pints  = 61,440  minims. 

One  pint,  0 = 16  fluidounces  = 7,680  minims. 

One  fluidounce,  fg  = 8 fluidrachms  = 480  minims. 

One  fluidrachm,  f^  = 60  minims. 

One  minim,  tt^  = 1 minim. 


In  this  work  the  term  gallon  is  not  used,  that  measure  being  j 
always  expressed  in  pints.  i 

At  the  temperature  of  60^,  a pint  of  distilled  water  weighs  7291.2  I 
grains,  a fluidounce  455.7  grains. 

The  Metric  System  of  weights  (the  word  metric  is  from  the  Greek  j 
metron,  measure)  is  greatly  to  be  preferred  to  all  others,  the  i 
relation  of  the  metric  weights  of  all  denominations  to  measures  of  ! 
length,  capacity,  and  surface  being  so  simple  as  to  be  within  the  per-  i 
feet  comprehension  of  a child  ; while  under  the  British  and  American  ; 
plans  the  weights  have  no  such  relation,  either  with  each  other  or  with  | 
the  various  measures.  Moreover  the  metric  system  is  in  perfect  har-  i 
mony  with  the  universal  method  of  counting;  it  is  a decimal  sy-stem.  i 
[It  is  perhaps  impossible  to  realize,  much  more  express,  the  ad-  i 
vantages  we  enjoy  from  the  fact  that  in  every  country  of  the  world  i 
the  system  of  numeration  is  identical.  That  system  is  the  decimal.  ! 
Whatever  language  a man  speaks,  his  method  of  numbering  is  deci-  | 
mal ; his  talk  concerning  number  is  decimal ; his  written  or  printed  I 
signs  signifying  number  are  decimal.  With  the  figures  1,  2,  3,  4,  5,  ' 
6,  7,  8,  9,  0 he  represents  all  possible  variation  in  number,  the  posi-  i 
tion  of  a figure  in  reference  to  its  companions  alone  determining  its 
value,  a figure  on  the  left  hand  of  any  other  figure  in  an  allocation  of 
numeral  symbols  (for  example,  1871)  having  ten  times  the  value  of 
that  figure,  while  the  figure  on  the  right  hand  of  any  other  has  a ; 
tenth  of  the  value  of  that  other.  When  the  youngest  pupil  is  asked  ' 
how  many  units  there  are  in  1871,  he  smiles  at  the  simplicity  of  the  i 
question,  and  says  1871.  How  many  tens?  187,  and  1 over.  How  , 
many  hundreds?  18,  and  71  over.  How  many  thousands ? 1,  and  > 
871  over.  But  if  he  is  asked  how  many  scruples  there  are  in  1871  : 
grains,  how  many  drachms,  how  many  ounces — he  first  inquires  which  ' 
drachms  or  which  ounces  are  meant,  avoirdupois  ounces,  troy  ounces,  ! 


WEIGHTS  AND  MEASURES. 


455 


w wine  ounces,  and  then  brings  out  his  slate  and  pencil.  And  so 
with  the  pints  or  gallons  in  1871  fluidounces,  or  the  feet  and  yards 
in  1871  inches,  or  the  pence,  shillings,  and  pounds  in  1871  farthings ; 
to  say  nothing  of  cross  questions,  such  as  the  value  of  1871  articles 
at  2 dollars  *and  20  cents  per  dozen,  or  of  the  perplexity  caused  by 
the  varying  values  of  several  individual  weights  or  of  measures  of 
length,  capacity,  and  surface  in  different  parts  of  the  country.  What 
is  desired  is,  that  there  should  be  an  equally  simple  decimal  relation 
among  weights  and  measures  and  coins  as  already  universally  exists 
among  numbers.  This  condition  of  things  having  already  been  in- 
troduced into  most  other  countries,  there  is  no  good  reason  why  it 
should  not  be  accomplished  in  the  United  States  and  Great  Britain.] 
The  Metric  System  of  weights  and  measures  is  founded  on  the 
metre.  The  engraving  represents  a pocket  folding  measure,  the 
tenth  part  of  a metre  in  length,  divided  into  10  centimetres,  and 
each  centimetre  into  10  millimetres. 


iinp'in 

TTll|llll 

iD'iiaj! 

lUillLIJ. 

— 

12 

3 

± Cr^ 

6 

7 

8 

9 

The  Decimetre. 


The  units  of  the  system  with  their  multiples  and  submultiples  are 
as  follows : — 

Units. 

Length. — The  Unit  of  Length  is  the  Metre,  derived  from  the 
measurement  of  the  Quadrant  of  a Meridian  of  the  Earth.  (Prac- 
tically it  is  the  length  of  certain  carefully  preserved  bars  of  metal, 
from  which  copies  have  been  taken.) 

Surface. — The  Unity  of  Surface  is  the  Are,  which  is  the  Square 
of  Ten  Metres. 

Capacity. — The  Unity  of  Capacity  is  the  Litre,  which  is  the 
Cube  of  a Tenth  Part  of  a Metre. 

Weight. — The  Unit  of  Weight  is  the  Gram,  which  is  the  Weight 
of  that  quantity  of  distilled  water,  at  its  maximum  density  (4^  0.), 
which  fills  a Cube  of  the  One-hundredth  part  of  the  Metre. 

Table. 

Note. — Multiples  are  denoted  by  the  Greek  words Deka,”  Ten, 
“ Hecto,”  Hundred,  “ Kilo,”  Thousand. 

Subdivisions,  by  the  Latin  words,  “ Deci,”  One-tenth, 


‘ Centi,”  One-hundredth, 

Milli,’’  One-thousandth. 

Quantities. 

Length. 

Surface. 

Capacity. 

Weight. 

1000 

Kilo-metre 

. . . 

Kilo-litre 

Kilo-gram 

100 

Hecto-metre 

Hectare 

Hecto-litre 

Hecto-gram 

10 

Deka-metre 

I)eka-litre 

l)eka-gram 

1 (Units)  METRE 

ARE 

LITRE 

GRAM 

.1 

l)eci-metre 

. . . 

Deci-litre 

Deci-gram 

.01 

Centi-metre 

Centiare 

Centi-litre 

Centi-gram 

.001 

Milli-metre 

Milli-litre 

Milli-gram 

456 


QUANTITATIVE  ANALYSIS. 


When  the  metric  method  is  exclusively  adopted  these  Units  and 
Table,  comprising  the  entire  System  of  AVeights  and  Measures,  re- 
present all  that  will  be  essential  to  be  learned  in  lieu  of  the  numerous 
and  complicated  Tables  hitherto  in  use.  Adopting  the  style  of  ele- 
mentary books  on  Arithmetic,  the  Table  may  be  expanded  in  the 
following  manner : — 


10  Milligrams 
10  Centigrams 
10  Decigrams 
10  Grams 
10  Dekagrams 
10  Hectograms 


make  1 centigram. 
“ 1 decigram. 

“ 1 gram. 

‘‘  1 dekagram. 

“ 1 hectogram, 

1 kilogram. 


10  Millilitres  make  1 centilitre, 
etc. 


10  Millimetres  make  1 centimetre, 
etc. 


The  following  approximate  equivalents  of  metrical  units  should  be 
committed  to  memory  ; — 

1 Metre  = 3 feet  3 inches  and  3 eighths. 

1 Are  = a square  whose  side  is  11  yards. 

1 Litre  = If  pint. 

1 Gramme  = ih^  grains. 

The  Metric  Ton  of  1000  Kilo-grammes  = 19  cwt.  2 qrs.  20  lbs.  10  ozs. 
The  Kilo-gramme  = 2 lbs.  3f  ozs.  nearly. 

The  Hect-are  = 2^  acres  nearly. 

For  exact  equivalents,  in  many  forms,  see  pages  461  and  462. 
(The  word  gramme  is,  in  English,  usually  written  gram.) 


Decimal  Coinage. — In  most  countries  where  the  metric  system  of 
weights  and  measures  is  employed,  a decimal  division  of  coins  is  also 
adopted.  This  course,  conjoined  with  the  ordinary  decimal  method 
of  enumerating,  which  fortunately  is  in  universal  use,  renders  calcu- 
lations of  all  kinds  most  simple — easy  to  an  extent  which  cannot  be 
conceived  in  countries  like  England,  where  the  operations  of  weigh- 
ing, measuring,  paying,  and  counting  have  only  the  most  absurdly 
intricate  relations  to  each  other.  i 


The  General  Council  under  whose  authority  the  British  Pharma-  j 
copoeia  is  issued  encourages  medical  practitioners  and  pharmacists  in  j 
the  adoption  of  the  metric  sj^stem,  and  gives  the  annexed  statement  j 
of  metric  weights  and  measures.  j 


WEIGHTS  AND  MEASURES. 


457 


WEIGHTS  AND  MEASUEES  OF  THE  METEICAL 
SYSTEM. 


(From  the  British  Pharmacopoeia,  of  1867.) 

WEIGHTS. 


Milligramme  = the  thousandth  part  of  one  grm.  or  0.001  grin. 

Centigramme  = the  hundredth  “ 0.01  “ 

Decigramme  = the  tenth  “ 0.1  “ 

Gramme  = weight  of  a cubic  centimetre  of 

water  at  4^  C.  1.0  ‘‘ 

Decagramme  ==  ten  grammes  10.0  “ 

Hectogramme  = one  hundred  grammes  100.0  “ 

Kilogramme  = one  thousand  grammes  1000.0  (1  kilo.) 


MEASURES  OF  CAPACITY. 

1 Millilitre  = 1 cub.  centim.  or  the  mea.  of  1 gram,  of  water. 

1 Centilitre  = 10  “ 10  “ “ 

1 Decilitre  = 100  “ “ 100  “ “ 

1 Litre  = 1000  “ 1000  “ (1  kilo.). 


MEASURES  OF  LENGTH. 

1 Millimetre  = the  thousandth  part  of  one  metre  or  0.001  metre. 

1 Centimetre  = the  hundredth  “ 0.01  “ 

1 Decimetre  = the  tenth  “ 0.1  “ 

1 Metre  = the  ten-millionth  part  of  a quarter  of  the  meridian 

of  the  earth. 

The  National  Convention  for  revising  the  Pharmacopoeia  of  the 
United  States  also  recognizes  the  claims  of  the  metric  system  of 
weights  and  measures  by  giving,  in  the  recent  (fifth)  edition  of  the 
Pharmacopoeia,  Tables  of  the  units  of  the  metrical  system  with  their 
multiples  and  submultiples,  similar  to  the  foregoing,  and  the  follow- 
ing Tables  showing  the  relation  to  each  other  of  the  metrical  and 
official  or  Troy  systems. 


39 


458 


QUANTITATIVE  ANALYSTS 


RELATION  OF  WEIGHTS  OF  THE  U.  S.  PHARMACOPCEIA  TO  METRICAL  WEIGHTS. 


Fraction  of  a grain  in 

Grains  in  equivalent 

Drachms,  Ounces,  and 
Pounds  in  equivalent 

Milligrammes. 

Metrical  weights. 

metrical  weights. 

Grain. 

Milligramme. 

Grains. 

Centigrammes. 

Drachms.  Grammes. 

= 

1.012 

1 

= 6.479 

1 = 3.887 

eV 

= 

1.079 

Decigrammes. 

2 = 7.775 

-50 

=3 

1.295 

2 

= 1.295 

Decagrammes. 

48 

= 

1.349 

3 

= 1.943 

3 = 1.166 

1 

?0 

= 

1.619 

4 

= 2.591 

4 = 1.555 

ih 

= 

1.799 

5 

= 3.239 

5 ==  1.943 

TU 

= 

2.159 

6 

= 3.887 

6 = 2.332 

1 

2o 

= 

2.591 

7 

= 4.535 

7 = 2.721 

1 

2¥ 

= 

2.699 

8 

= 5.183 

Ounces. 

1 

2 0 

= 

3.239 

9 

= 5.831 

1 = 3.1103 

1 

T6 

= 

4.049 

10 

= 6.479 

2 = 6.2206 

1 

T3 

= 

4.319 

12 

= 7.775 

3 = 9.3309 

T2 

= 

5.399 

15 

= 9.718 

Hectogrammes. 

To 

= 

6.479 

Grammes. 

4 = 1.2441 

i 

= 

8.098 

16 

= 1.036 

5 = 1.5551 

i 

= 

10.798 

20 

= 1.295 

6 = 1.8661 

T 

= 

12  958 

24 

= 1.555 

7 = 2.1772 

i 

= 

16.197 

25 

= 1.619 

8 = 2.4882 

k 

= 

21.597 

30 

= 1.943 

9 = 2.7992 

1 

2 

= 

32.395 

40 

= 2.591 

10  = 3.1103 

50 

60 

= 3.239 

= -3.887 

11  = 3.4213 

Pounds. 

1 = 3.7324 

2 = 7.4648 

Kilogrammes. 

3 = 1.1197 

WEIGHTS  AND  MEASURES. 


459 


RELATION  OP  METRICAL  WEIGHTS  TO  WEIGHTS  OF  THE  U.  S.  PflARMACOPCEIA. 


Metrical 

Weights. 

Exact 

Approximate 

Metrical 

Approximate 

equivalents 
in  grains. 

equivalents 
in  grains. 

Weights,  equivalents 
® in  grains. 

equivalents  in 
Troy  Weight. 

Milligrammes. 

Grammes. 

1 

= 

.0154 

1 

■e? 

1 = 

15.434 

gr.  XV. 

2 

= 

.0308 

1 

3 2 

2 = 

30.868 

:^ss. 

3 

== 

.0463 

2V 

3 = 

46.302 

*9ij- 

4 

= 

.0617 

tV 

4 = 

61.736 

Si- 

5 

= 

.0771 

1 

T3 

5 = 

77.170 

9iv. 

6 

= 

.0926 

1 

IT 

6 = 

92.604 

5iss. 

7 

= 

.1080 

1 

■9 

7 = 

108.038 

9vs3. 

8 

= 

.1234 

1 

8 

8 = 

123.472 

5ij* 

9 

= 

.1389 

1 

y 

9 = 

138.906 

9vij. 

Centigrammes. 

Decagrammes. 

1 

= 

.1543 

1 

6 

1 = 

154.340 

%iiss. 

2 

= 

.3086 

i 

2 = 

308.680 

5^- 

3 

= 

.4630 

A 

3 = 

463.020 

5viiss. 

4 

= 

.6173 

A 

4 = 

617.360 

5x. 

5 

= 

.7717 

i 

5 = 

771.701 

Sxiij. 

6 

=r 

.9260 

To 

6 = 

926.041 

5xv. 

7 

= 

1.0803 

1 

7 = 

1,080.381 

Sxviij- 

8 

= 

1.2347 

n 

8 = 

1,234.721 

5xx. 

9 

= 

1.3890 

u 

9 = 

1,389.062 

3xxiij. 

Decigrammes. 

Hectogrammes. 

1 

= 

1.543 

n 

1 = 

1,543.402 

.?iiJ  9^. 

2 

= 

3.086 

3 

2 = 

3,086.804 

3 

= 

4.630 

3 == 

4,630.206 

.^ix  3v. 

4 

= 

6.173 

6 

4 = 

6,173.609 

Ibi  ^vij. 

5 

= 

7.717 

5 = 

7,717.011 

Ibi  |iv. 

6 

= 

9.260 

9 

6 = 

9,260.413 

Ibi  |vij. 

7 

= 

10.803 

11 

7 = 

10,803.816 

Ibi  gx  3iv. 

8 

= 

12.347 

12,1 

8 = 

12,347.218 

^i.i  §i  5^- 

9 

= 

13.890 

14 

9 = 

13,890.620 

Ibij  gv. 

Kilogramme. 

1 = 

15,434.023 

J^ij  gviij. 

Myriogramme. 

1 = 

154,340.23  1 

ffixxvi 
gix.  3iv. 

The  following  Tables,  from  the  British  Pharmacopoeia,  the  United 
States  Pharmacopoeia,  and  the  Diary  of  Messrs.  De  La  Rue,  will  be 
found  useful  for  reference  : — 


WEIGHTS  AND  MEASURES  OF  THE  BRITISH  PHAR- 
MACOPCEIA  OF  1867. 

WEIGHTS. 

I Grain  gr. 

I Ounce  oz.  = 437.5  grains. 

1 Pound  lb.  ==  16  ounces  = 7000  “ 


4G0 


QUANTITATIVE  ANALYSIS. 


MEASURES  OF  CAPACITY. 


1 Minim 

min. 

1 Fluidrachm 

fl.  dr.  = 

60  minims. 

1 Fluidounce 

fi.  oz.  = 

8 fluidrachms. 

1 Pint 

0.  = 

20  fluidounces. 

1 Gallon 

c.  = 

8 pints. 

MEASURES  OF  LENGTH. 

1 line  = L 

inch. 

1 inch  = 39^^  seconds-pendulum. 

12  = 1 foot. 

36  “ = 3 feet  = 1 yard. 

Length  of  pendulum  vibrating  seconds  of  mean  ] 

time  in  the  latitude  of  London,  in  a vacuum  at  >39.1393  inches. 

the  level  of  the  sea j 

(1  cubic  inch  of  distilled  water  at  62^  F.  and  30  inch  Barom.  = 252.458 
grains.) 


RELATION  OF  MEASURES  TO  WEIGHTS. 


1 Minim  is  the  measure  of 
1 Fluidrachm  “ 

1 Fluidoiince  ‘‘  1 ounce  or 

1 Pint  1.25  pound  or 

1 Grallon  10  pounds  or 


0.91  grain  of  water,  j 

54.68  grains  of  water.  | 

437.5  “ I 

8750.0  ) 

70,000.0 


RRLATION  OF  WEIGHTS  AND  MEASURES  OF  THE  U.  S.  PH ARMACOPCEIA  TO  j 
EACH  OTHER.  | 

la  distilled  water  at  a temperature  of  60^.  j 


One  Pound  = 0.7900031  Pint  = 6067.2238  Minims. 

One  Ounce  = 1.0533376  Fluidounce  = 505.6013  Minims. 

One  Drachm  = 1.0533376  Fluidrachm  = 63.2002  Minims. 

One  Scruple  = 21.0667  Minims.  | 

One  Grain  = 1.0533  Minim,  j 

One  Gallon  = 10.1265427  Pounds  = 58328.8862  Grains,  i 

One  Pint  = 1.2658178  Pound  = 7291.1107  Grains.  I 

One  Fluidounce  = 0.9493633  Ounce  = 455,6944  Grains,  i 

One  Fluidrachm  = 0.9493633  Drachm  = 56.9618  Grains,  i 

One  Minim  = 0.9493  Grain.  » 


RELATION  OF  MEASURES  OF  THE  U. 

One  Gallon  = 
One  Pint  = 

One  Fluidounce  = 
One  Fluidrachm  = 
One  Minim  = 


. PHARMACOPCEIA  TO  CUBIC  MEASURE. 

31.  Cubic  Inches. 

28.875  Cubic  Inches. 

1.80468  Cubic  Inch. 

0.22558  Cubic  Inch. 

0.00375  Cubic  Inch. 


I 


Metrical  Measures  of  Length. 


WEIGHTS  AND  MEASURES. 


461 


T— I ^ CO 

O CD  (M  rH  CO  00 
O O CO  (M  t— I CO 
O O O CO  (M  rH 
O O O O CO 
O O O O O CO 

o o o o o o 
o o o o o o 


GO  cq 
CO  CO 


CO  oq 

O CO 


bJO'O 

p§  II 


rC  rO 

CO  t> 

c 

bo"^ 

c cq 


CO  cq 
CO  00 
^ CO 
in 

o in 
o o 
o o 
o o 


CO  m lo 
I— I CO  lO 
00  I-H  CO 
CO  00  rH 
^ CO  00 
to  -rti  CO 
O to 

O O to 


o o o 
to  o o 
to  to  o 
CO  to  to 
!— I CO  to 


00  T 


i CO 


CO  00  I _ 
TjH  CO  00 
to  ^ CO 
to 

to 


CO  CO 
CO  CO 
Oi  CO 

o Cb 

r— t O 
O nH 
O O 

o o 


CO  rH  O O O O 
CO  CO  rH  O O O 
CO  CO  CO  T— I O O 
CO  CO  CO  CO  1— I o 
05  CO  CO  CO  CO  rH 
O 05  CO  CO  CO  CO 
rH  O 05  CO  CO  CO 
O rH  O Oi  CO  cd 
rH  O 05  CO 
r-H  O 05 
rH  O 


rH  05  O 05  (rq  O 
GO  O 05  C5  05  (M 
oq  GO  O CO  05  05 
CO  cq  CO  o GO  05 
O CO  cq  CO  O GO 
o o CO  cq  CO  o 


o o 
o o 
cq  o 

05 

05  05 
00  05 

) o cd 

I GO  O 
5 cq  GO 
CO  cq 


t-rHOOCDOOOO 
C0  1'-0t^05000 
05  CO  t'-  I'-  o-  o o 

coo5coj:ioi'^o5o 

O CO^  05  o 05 

o o'  cd  ^ cd  o 

Oj  05  CO  o 
00  CO  05  CO  1^- 
CO  05  CO 
CO  05 


^ 'H 


<D  5-1 


<D  ^ 

S H§ 


-4-j  f]:)  p O) 


S o s 

o S .2 


<u 


G ’o  o O r-H 

pgfia 


V.  O’t 


CO  CO 
rfl  05 
1—1  o 
05  -O 


p ^ 

'S'S 

s.§ 

o 
G 0^ 
0;  ^ 
^05 
tiO 

05  05 
05  r- 
CO  Ttl 

in  o 

cq*  cd 


f—  o 

be  CO 
C O 


— o 

be  05 

O QO 


1— I I-H 

L'-  rH  CO 
rH 

cq  rH 

O 'cjH  rH 

o cq  L'- 

O O 'P 

o o (cq 


to  ^ 
CO  to  cq 
00  'rti  1-^ 
05  00  to 
O 00  ^ 
O 05  00 
O O 00 
O O 05 


CO  O 05 
GO  05  lO 
CO  cq  05 
m GO  cb 
05  CO  cq 
CO  to  00 
o 05  CO 

o cd  to 

05 


CO  o cq 
CO  cq  o 
O CO  CO 

CO  CO  cq 

05  o CO 
rH  O CO 


H 05 


05  00 

05  CO  1— I 
cq  05 
rfl  <05  CO 
CO  cq  05 

ip  -p  05 

<o  cd  cq* 

rH  i^  'ciH 
O CO 
rH  IH- 

o 


. . (D 

s 

03  o 

^ e.  ?H 

p-  ^ 03 
2 13  G 
S S cG 
02 

2 s 

G d o 
CQ  cc  pH 
° o o 

G rH 

.2  O S 

g £ s 


o ^ 
H G 
G -H 
G ^ 

02 

to 

I— i O 

r—  rH 

<05 

o ^ 
o ^ 
CO  o 
00  'p 
o o 


G (O 
G H 


G o 
(O  03 
03 

03  03 
^ u 
G G 
G G 
cr*  cr* 
02  02 

05  CO 
CO  GO 
CO  CO 
CO  <05 


G G 
G G 
cr*  CG 
02  02 


39* 


Metrical  Measures  of  Capacity. 


462 


QUANTITATIVE  ANALYSIS. 


A 

cS  t'- 

bco 


IIS  I 

M t>l  o 
C t-  c 

C (?q  -fH 

l!l 


o 

3 

s 


^S.s 

eo 


!C<?1— IQCiOOCrs 
I'-Oi— IC<^O00'>^t^lO 
(ML'-iOi— l(^qOOO'^ 
O (M  »-0  1— I O OO 
oocMt'-m,-H(rqo 

OOOcMl-^iOrHC^ 

oooocMt^ir:),— I 


o ^ 

(rq  o 

CS| 
O CS| 

o.  o 
o o 


r—  t- 

Oi  O 
O 05 

o o 
(rq  o 

(M 
O O'! 


o o o o 


00  1-^  t"  »o 
o 1'-  O 1^- 
o CO  L—  o 
05  o CO  t- 
o 05  to  CO 
O o 05  to 

C<1  O O 05 

oi  o o 

Ol  o 

O?  C<1 


CO.— 

It-  CO  O !>•  I'-  CO  I 

I t'-  CO  o 

O ^ CO  ^ ^ 

o O t-H  ^ to  O -C^ 

O00_ji:^«oor^ 

rH  CO  O 
I— I CO 

rH  I'- 


iOCOC<ll^-COOOr-lt'- 
COuOCOr-ICOiOQOO 
OCOiOCOr-HCOlOQO 
O O CO  1(0  CO'  rH  CO  uo 
OOOCOiC-COr—iCO 
OOOOCOiOCOr— I 


CO  t-  .— I lO  <M  KO  (M  c 

O (C^  O 1(0  .— I KO  r 

.— I o (oq  I'-  o 1(0  .— I 1 

CO  t— I o (cq  t'-  o 1(0  r 

O CO  r-H  O (Tq  t'-  o * 


o <o  (^ 

^ BB 

o ’43  *43 


S .B-B  S 

0>  jO  ^ 

• N ^ 3 o 

■5  O 5^ 

§3  2-2 

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1 c:rain  = 0.064799  pram.  1 troy  =31.103496  prams.  1 lb.  av(l.=  0.453593  kilpr.  1 cwt.  = 50.802377  kilogrs. 


SPECIFIC  GRAVITY. 


463 


QUESTIONS  AND  EXERCISES. 

948.  Mention  some  advantages  of  a decimal  system  of  weights  and 
measures. 

949.  What  is  the  name  of  the  chief  unit  of  the  metric  decimal 
system  of  weights  and  measures  ? 

950.  Mention  the  names  of  the  metric  units  of  surface,  capacity, 
and  weight,  and  state  how  they  are  derived  from  the  unit  of  length. 

951.  How  are  multiples  of  metric  units  indicated  ? 

952.  State  the  designations  of  submultiples  of  metric  units. 

953.  How  many  metres  are  there  in  a kilometre  ? 

954.  How  many  millimetres  in  a metre  ? 

955.  How  many  grams  in  5 kilograms  ? 

956.  How  many  milligrams  in  13j  grams  ? 

957.  In  1869  centigrams  how  many  grams  ? 

958.  In  a metre  measure  5 centimetres  wide  and  1 centimetre 
thick  how  many  cubic  centimetres  ? 

959.  How  many  litres  are  contained  in  a cubic  metre  of  any 
liquid? 

960.  State  the  British  equivalent  of  the  metre. 

961.  How  many  square  yards  in  an  are  ? 

962.  How  many  fluidounces  in  a litre  ? 

963.  How  many  ounces  in  a kilogram  ? 

964.  Give  the  relation  of  a metric  ton  (1000  kilos.)  to  a British 
ton. 

965.  How  many  grains  are  there  in  1 ton  ? 

966.  How  many  ounces  in  1 ton  ? 

967.  How  many  grains  of  water  in  1 fluidrachm  ? 

968.  How  many  minims  in  1 pint  ? 

969.  How  many  grains  in  1 pint  of  water  ? 

970.  Whence  is  the  British  unit  of  length  derived. 


Specific  Weight  or  Specific  Gravity. 

The  specific  weight  of  a substance  is  its  weight  in  comparison 
with  weights  of  similar  bulks  of  other  substances.  This  compara- 
tive heaviness  of  solids, and  liquids  is  conventionally  expressed  in 
relation  to  water : they  are  considered  as  being  lighter  or  heavier 
than  water.  Thus,  water  being  regarded  as  unity  = 1,  the  relative 
weight,  or  specific  w^eight,  of  ether  is  represented  by  the  figures 
.720  (it  is  nearly  three-fourths,  .750,  the  weight  of  water),  oil  of 
vitriol  by  1.843  (it  is  nearly  twice,  2.000,  as  heavy  as  water).  The 
specific  weight  of  substances  is,  moreover,  the  weight  of  similar 
volumes  at  sixty  degrees  (60*^  F.) ; for  the  weight  of  a definite  volume 
of  any  substance  will  vary  according  to  temperature,  becoming 
heavier  when  cooled,  and  lighter  when  heated,  different  bodies  (gases 
excepted)  differing  in  their  rate  of  contraction  and  expansion.  While, 
then,  specific  weight,  or  conventionally  specific  gravity^  is  truly  the 
comparative  weight  of  equal  bulks,  the  numbers  which  in  America 
and  Great  Britain  commonly  represent  specific  gravities  are  the 


4G4 


QUANTITATIVE  ANALYSIS. 


comparative  weights  of  equal  bulks  at  60^  F.,  water  being  taken  as 
unity.*  The  standard  of  comparison  for  gases  was  formerly  air,  but 
is  now  usually  hydrogen. 

« 

Specific  Gravity  of  Liquids. 

Procure  any  small  bottle  bolding  from  100  to  1000 
grains,  and  having  a narrow  neck ; counterpoise  it  in  a 
delicate  balance ; fill  it  to  about  halfway  up  the  neck  with 
pure  distilled  water  having  a temperature  of  60°  F. ; 
ascertain  the  weight  of  the  water,  and,  for  convenience, 
add  or  subtract  a drop  or  two,  so  that  the  weight  shall  be 
a round  number  of  grains ; mark  the  neck  by  a diamond 
or  file-point  at  the  part  cut  by  the  lower  edge  of  the  curved 
surface  of  the  water.  Consecutively  fill  up  the  bottle  to  the 
neck-mark  with  several  other  liquids,  cooled  or  warmed  to 
G0°  F.,  first  rinsing  out  the  bottle  once  or  twice  with  a 
small  quantity  of  each  liquid,  and  note  the  weights;  the 
respective  figures  will  represent  the  relative  weights  of 
equal  bulks  of  the  liquids.  If  the  capacit}"  of  the  bottle 
is  10,  100,  or  1000  grains,  the  resulting  weights  will,  with- 
out calculation,  show  the  specific  gravities  of  the  liquids ; 
if  any  other  number,  a rule-of-three  sum  must  be  w^orked 
out  to  ascertain  the  w^eight  of  the  liquids  as  compared  wdth 
1 (or  1.000)  of  w^ater.  Bottles  conveniently  adjusted  to 
contain  250,  500,  or  1000  grains,  or  100  or  50  grammes  of 
water,  when  filled  to  the  top  of  their  perforated  stopper, 
and  other  forms  of  the  instrument,  are  sold  by  all  chemical 
apparatus  makers. 

The  following  are  the  stated  specific  gravities  of  official  liquids : — 


Acid,  acetic,  B,  P 1.044 

“ U.  S.  P 1.047 

diluted,  B.  B.  and  U.  S.  P 1.006 

“ “ glacial 1.065  to  1.066 

“ carbolic 1.065 

hydriodic,  diluted 1.112 


* The  true  weight  of  the  body  is  its  weight  in  air  plus  the  weight 
of  an  equal  bulk  of  air  and  minus  the  weight  of  a bulk  of  air  equal 
to  tlie  bulk  of  brass  or  other  weights  employed  ; or,  in  other  words,  its 
weight  in  vacuo  uninfluenced  by  the  buoyancy  of  the  air  ; but  such  a 
correction  of  the  weight  of  a body  is  seldom  necessary  or,  indeed, 
desirable.  Density  is  sometimes  improperly  regarded  as  synonymous 
with  specific  yravity.  It  is  true  that  the  density  of  a body  is  in  exact 
proportion  to  its  specific  gravity  ; but  tlie  former  is  more  correctly  the 
comparative  bulk  of  equal  weights,  while  specific  gravity  is  the  com- 
parative weight  of  equal  bulks. 


SPECIFIC  GRAVITY. 


465 


Acid,  liydrocliloric,  B.  P.  and  U.  S.  P 1.160 

“ “ diluted,  B.  P 1.052 

“ “ U.  S.  P 1.038 

“ hydrocyanic,  B.  P.  and  U.  S.  P 0.997 

‘‘  lactic,  U.  S.  P 1.212 

Nitric,  B.  P.  and  U.  S.  P.  1.420 

“ ‘‘  diluted,  B.  P 1.101 

“ U.  S.  P 1.068 

“ nitro-hydrochloric 1.074 

“ phosphoric  diluted,  B.  P . . 1.080 

“ U.  S.  P 1.056 

sulphuric,  B.  P.  and  U.  S.  P 1.843 

“ “ aromatic 0.927 

“ “ diluted,  B.  P 1.094 

“ “ U.  S.  P 1.082 

“ sulphurous,  solution  of,  B.  P 1.040 

“ ‘‘  “ U.  S.  P 1.035 

Alcohol,  U.  S.  P 0.835 

absolute 0.795 

“ (rectified  spirit,  84  per  cent.) 0.838 

“ (proof  spirit,  49  per  cent.)  0.920 

“ dilutum,  U.  S.  P 0.941 

“ fortius,  U.  S.  P 0.817 

‘‘  amylic,  B.  P.  and  U.  S.  P 0.818 

Ammonia,  aromatic  spirit  of,  B.  P 0.870 

“ stronger  water  of,  U.  S.  P 0.900 

solution  of,  B.  P 0.959 

“ strong  solution  of,  B.  P 0.891 

Antimony,  solution  of  chloride  of,  B.  P 1.470 

Arsenic,  hydrochloric  solution  of,  B.  P 1.009 

Arsenical  solution  [Liquor  Arsenicdlis),  B.  B.  . . 1.009 

Benzol,  B.  P 0.850 

Bismuth  and  ammonia,  solution  of  citrate  of,  B.  P.  1.122 

Bromine . 2.966 

Chlorine  solution  of,  B.  P 1.003 

Chloroform,  B.  P.  and  U.  S.  P 1.490 

“ spirit  of,  B.  P 0.871 

Cinchona,  liquid  extract  of  yellow,  B.  P.  (about)  . 1.100 

Creasote,  U.  S.  P 1.046 

‘‘  1.071 

Ether,  B.  P 0.735 

“ U.  S.  P 0.750 

“ pure,  B.  P 0.720 

“ fortior,  U.  S.  P 0.728 

Glycerine,  B.  P.  and  U.  S.  P 1.250 

Iron,  solution  of  pernitrate  of,  B.  P 1.107 

“ “ U.  S.  P 1.065 

“ “ “ persulpate  of,  B.  P 1.441 

“ “ U.  S.  P.  ....  1.320 

“ strong  solution  of  perchloride  of,  B.  P.  . . . 1.338 
“ tincture  of  perchloride  of,  B.  P.  and  U.  S.  P.  0.992 


466 


QUANTITATIVE  ANALYSTS. 


liead,  solution  of  subacetate  of,  B.  P 1.260 

“ “ “ ‘‘  “ U.  S.  P 1.267 

Lime,  saccharated  solution  of,  B,  P 1.052 

“ solution  of  chlorinated,  B.  P * . . 1.035 

Mercury  (at  0^  C.=  320  F.) 13.596 

“ (at  150.55  C.=:60O  F.) 13.560 

“ acid  solution  of  nitrate  of 2.246 

“ “ “ “ “ U.  S.  P.  . . . 2.165 

Nitre,  sweet  spirit  of 0.845 

“ “ U.  S.  P 0.837 

Oil  of  mustard,  B.  P 1.015 

Potash,  solution  of,  B.  P 1.058 

“ ‘‘  “ U.  S.  P 1.065 

Soda,  “ B.  P 1.047 

“ U.  S.  P 1.071 

“ “ chlorinated,  B.  P 1.103 

“ “ ‘‘  “ U.  S.  P 1.045 

Squill,  oxymel  of,  B.  P 1.320 

Syrup,  B.  P 1.330 

“ U.  S.  P 1.317 

“ of  buckthorn,  B.  P 1.320 

“ of  ginger 

“ of  hemidesmus,  B.  P 1.335 

“ of  iodide  of  iron,  B.  P 1.385 

‘‘  of  lemons,  B.  P 1.340 

“ of  mulberries,  B.  P 1.330 

“ of  orange-flower,  B.  P 1.330 

“ of  “ peel,  B.  P 

“ of  phosphate  of  iron,  B.  P 

“ of  poppies,  B.  P 1.320 

‘‘  of  red  poppy,  B.  P 1.330 

“ of  “ roses,  B.  P 1.335 

“ of  rhubarb,  B.  P 

“ of  senna,  B.  P 1.310 

“ of  squill,  B.  P 

“ of  tolu,  B.  P 1.330 

Treacle,  B.  P (about)  1.400 


Hydrometers. — The  specific  gravity  of  liquids  may  be  ascertained, 
without  scales  and  weights,  by  means  of  an  hydrometer — an  instru- 
ment usually  of  glass,  having  a graduated  stem  and  a bulb  or  bulbs 
at  the  lower  part.  The  specific  gravity  of  a liquid  is  indicated  by 
the  depth  to  which  the  hydrometer  sinks  in  the  liquid,  the  zero  of 
the  scale  marking  the  depth  to  which  it  sinks  in  pure  water.  Hydro- 
meters constructed  for  special  purposes  are  known  under  the  names 
of  saccharometer,  galactometer,  elmometer,  urinometer,  alcoliometer. 
Hydrometers  require  a considerable  quantity  of  liquid  to  fairly  float 
them,  and  specific  .gravities  observed  with  them  are  less  delicate  and 
trustworthy  than  those  obtained  by  the  balance,  nevertheless  they 
are  exceedingly  useful  for  many  practical  purposes  where  the  employ- 
ment of  a delicate  balance  would  be  inadmissible. 


SPECIFIC  GRAVITY. 


467 


Specific  Gravity  of  Solids  in  Mass. 

Weigh  a piece  (50  to  250  grains)  of  any  solid  substance 
heavier  than  water  in  the  usual  manner.  Then  weigh  it  in 
water,  by  suspending  it  from  a shortened  balance  pan  by 
a fine  thread  or  hair  and  immersing  in  a vessel  of  water. 
The  buoyant  properties  of  the  water  will  cause  the  solid 
to  apparently  lose  weight ; this  loss  in  weight  is  the  exact 
weight  of  an  equal  hulk  of  water.  The  weight  of  the  sub- 
stance and  the  weight  of  an  equal  bulk  of  water  being  thus 
ascertained,  a rule-of-three  sum  shows  the  proportional 
weight  of  the  substance  to  1.000  of  water.  To  express 
the  same  thing  by  rule,  divide  the  weight  in  air  by  the  loss 
of  weight  in  water,  the  resulting  number  is  the  specific 
gravity  in  relation  to  1 part  of  water,  the  conventional 
standard  of  comparison. 

Verify  some  of  the  following  specific  gravities: — 


Aluminium 2.56 

Antimony 6.71 

Bismuth 9.83 

Coins,  English,  gold 17.69 

“ ‘‘  silver 10.30 

“ bronze 8.70 

Copper 8.95 

Gold 19.34 

Iron 7.84 

Lead 11.36 

Magnesium 1.74 

Marble 2.70 

Phosphorus 1.77 

Platinum 21.53 

Silver 10.53 

■ Sulphur 2.05 

Tin 7.29 

Zinc 7.14 


Specific  gravities  of  solid  substances  should  be  taken  in  water 
having  a temperature  of  about  60^  F.  The  body  should  be  im- 
mersed about  half  an  inch  below  the  surface  of  the  water ; adhering 
air-bubbles  must  be  carefully  removed ; the  body  must  be  quite  in- 
soluble in  water. 

Specific  Gravity  of  Solids  in  Powder  or  Small 
Fragments. 

Weigh  the  particles;  place  them  in  a counterpoised 
specific-gravity  bottle  of  known  capacity,  and  fill  up  with 
water,  taking  care  that  the  substance  is  thoroughly  wetted ; 


468 


QUANTITATIVE  ANALYSIS. 


again  weigh.  From  the  combined  weights  of  water  and 
substance  subtract  the  amount  due  to  the  substance ; the 
residue  is  the  weight  of  the  water.  Subtract  this  weight 
of  water  from  the  quantity  which  the  bottle  normally  con- 
tains ; the  residue  is  the  amount  of  water  displaced  by 
the  substance.  Having  thus  obtained  the  weights  of  equal 
bulks  of  water  and  substance,  a rule-of-three  sum  shows 
the  relation  of  the  weight  of  the  substance  to  1 part  of 
water,  the  specific  gravity. 

Or,  suspend  a cup,  short  glass  tube,  or  bucket  from  a 
shortened  balance-pan;  immerse  in  water;  counterpoise; 
place  the  weighed  powder  in  the  cup,  and  proceed  as  di- 
rected for  taking  the  specific  gravity  of  a solid  in  mass. 

This  operation  may  be  conducted  on  fragments  of  any  of  the  sub- 
stances the  specific  gravities  of  which  are  given  in  the  foregoing 
Table,  or  on  the  powdered  piece  of  marble  the  specific  gravity  of 
which  has  been  taken  in  mass.  The  specific  gravity  of  one  piece  of 
glass,  first  in  mass  then  in  powder,  may  be  ascertained ; the  result 
should  be  identical.  The  specific  gravity  of  shot  is  about  11.350; 
sand,  2.600;  mercury,  13.56.  , 

Specific  Gravity  of  Solids  Soluble  in  Water. 

Weigh  a piece  of  sugar  or  other  substance  soluble  in  i 
water;  suspend  it  from  a balance  in  the  usual  manner,  and  ■ 
weigh  it  in  turpentine,  benzol,  or  petroleum,  the  specific 
gravity  of  which  is  known  or  has  been  previously  deter- 
mined ; the  loss  in  weight  is  the  weight  of  an  equal  bulk 
of  the  turpentine.  Ascertain  the  weight  of  an  equal  bulk 
of  water  by  calculation. 

Sp.  gr.  of  , sp.  gr.  of  ^ ^ observed  ^ equal  bulk 
turpentine  ' water  * ’ bulk  of  turp.  ’ of  water. 

The  exact  weights  of  equal  bulks  of  sugar  and  water  being 
obtained,  the  weight  of  a bulk  of  sugar  corresponding  to 
one  of  water  is  shown  by  a rule-of-three  sum ; in  other 
words,  divide  the  weight  of  sugar  hy  that  of  the  equal 
bulk  of  water,  the  quotient  is  the  specific  gravity  of  sugar. 
The  specific  gravity  of  sugar  ranges  from  1.06Y  to  1.090. 

Specific  Gravity  of  Solids  Lighter  than  Water. 

This  is  obtained  in  a manner  similar  to  that  for  solids 
heavier  than  water;  but  the  light  body^  is  sunk  by  help  of 
a piece  of  heavy  metal,  the  bulk  of  water  which  the  hitter 
displaces  being  deducted  from  the  bulk  displaced  by  both;. 


SPECIFIC  GRAVITY. 


409 


the  remainder  is  the  weight  of  a bulk  of  water  equal  to  the 
bulk  of  the  light  body.  For  instance,  a piece  of  wood 
weighing  12  grammes  (or  grains)  is  tied  to  a piece  of  metal 
weighing  22  grammes,  the  loss  of  weight  of  the  metal  in 
water  having  been  previously  found  to  b^e  3 grammes.  The 
two,  weighing  34  grammes,  are  now  immersed,  and  the  loss 
in  weight  found  to  be  26  grammes.  But  of  this  loss  3 
grammes  have  been  proved  to  be  due  to  the  buoyant  action 
of  the  water  on  the  lead;  the  remaining  23,  therefore,  re- 
present the  same  effect  on  the  wood;  23  and  12,  therefore, 
represent  the  weights  of  equal  bulks  of  water  and  wood. 
As  23  are  to  12  so  is  1 to  .5211.  Or,  shortly,  as  before, 
divide  the  weight  in  air  by  the  weight  of  an  equal  bulk  of 
water;  .5217  is  the  specific  gravity  of  the  wood.  Another 
specimen  of  w^ood  may  be  found  to  be  three-fourths  (.750) 
the  weight  of  water,  and  others  heavier.  Cork  varies  from 
.100  to  .300. 


Specific  Gravity  of  Gases. 

This  operation  is  similar  to  that  for  liquids.  A globe  exhausted 
of  air  and  holding  from  1 to  4 litres  (or  quarts)  is  suspended  from  the 
arm  of  a balance,  and  counterpoised  by  a similar  flask.  ^Gases  are 
introduced  in  succession  and  their  weights  noted.  A rule-ot-three 
sum  shows  their  specific  gravity  in  relation  to  air  or  hydrogen,  which- 
ever be  taken  as  a standard. 

Correction  of  the  Volume  of  Gases  for  Pressure. — The  height  of 
the  barometer  at  the  time  of  manipulation  is  noted.  Remembering 
the  fact  that  “ the  bulk  of  a gas  is  inversely  as  the  pressure  to  which 
it  is  subjected”  (Boyle  and  Mariotte),  a simple  calculation  shows  the 
volume  which  the  gas  would  occupy  at  760  millimetres  (or  29.922 
inches),  the  standard  pressure.  (30  inches  is  sometimes  adopted  as 
the  standard  in  England."^)  Thus,  40  volumes  of  a gas  at  740  milli- 
metres pressure  are  reduced  to  39  when  the  pressure  becomes  760 
millimetres  (or  90  vols.  at  29  ins.  barom.  become  87  vols.  at  30 
inches) . 

Correction  of  the  Volume  of  Gases  for  Temperature. — This  is 
done  in  order  to  ascertain  what  volume  the  gas  would  occupy  at  0^ 
C.  (32°  F!)  or  15^.5  C.  (60°  F.),  according  to  the  standard  taken. 

* In  France  the  conventional  standard  height  of  the  barometer  is 
760  millimetres  at  OO  C.  (32P  F.)  ; in  England  it  is  30  inches,  the 
temperature  of  the  mercurial  column  being  60P  F.  760  millims.  is 
equivalent  to  29.922  inches  ; but  the  expansion  of  th-e  metal  between 
320  F.  and  60°  F.  increases  the  length  of  the  column  to  30.005 
inches.  The  standards  are,  therefore,  almost  identical,  difference  in 
true  length  being  counterbalanced  by  the  temperature  at  which  the 
length  is  observed. 

40 


470 


QUANTITATIVE  ANALYSIS. 


Gases  expand  about  0.3665*  per  cent,  of  their  volume  at  the 
freezing-point  of  water  for  every  C.  degree  (0.2036,  or  ^ for  every 
F.  degree)  (Kegnault).  Thus  8 volumes  of  gas  at  0^  C.  will  become 
8.293  at  10^  C. ; for  if  100  become  103.665  on  being  increased  in  i 
temperature  10^  C.,  8 will  become  8.293  (or  if  100  become  102.036  i 
on  being  increased  10^  F.,  8 will  become  8.1629).  | 

Vapor-density. — Vapors  are  those  gases  which  condense  to  liquids' 
at  common  temperatures.  By  the  density  of  a vapor  is  meant  its 
specific  gravity.  The  density  of  a vapor  is  the  ratio  of  any  given 
volume  to  a similar  volume  of  air  or  hydrogen  at  the  same  tempera- 
ture and  pressure.  But,  for  convenience  of  comparison,  this  experi- 
mental specific  gravity  is  referred,  by  calculation  as  just  described 
for  permanent  gases,  to  a temperature  of  0^  C.,  and  760  millimetres  j 
barom.  A teaspoonful  or  so  of  liquid  is  placed  in  a weighed  flask  of  | 
about  the  capacity  of  a common  tumbler  and  having  a capillary  i 
neck  ; the  flask  is  heated  in  an  oil-bath  to  a temperature  considerably  j 
above  the  boiling-point  of  the  liquid ; at  the  moment  vapor  ceases  | 
to  escape,  the  neck  is  sealed  by  a blowpipe-flame,  and  the  tempera- 
ture of  the  bath  noted ; the  flask  is  then  removed,  cooled,  cleaned, 
and  weighed  ; the  height  of  the  barometer  is  also  taken.  The  neck 
of  the  flask  is  next  broken  off  beneath  the  surface  of  w^ater  or  mer- 
cury (which  rush  in  and  fill  it),  and  again  weighed,  by  which  its  capa- 
city in  cub.  centims.  is  found.  From  these  data  the  volume  of  vapor 
yielded  by  a given  weight  of  liquid  is  ascertained  by  a fcAv  obvious 
calculations.  The  capacity  of  the  globe  having  been  ascertained, 
the  Tveight  of  an  equal  bulk  of  airf  is  obtained  by  a rule-of-three 
sum.  This  weight  of  air  is  deducted  from  the  original  w^eight  of  the 
flash,  which  gives  the  true  weight  of  the  glass.  The  weight  of  the 
glass  is  next  subtracted  from  the  weight  of  the  flask  and  contained 
vapor  (now  condensed),  which  gives  the  weight  of  material  used  in 
the  experiment.  The  volume  which  this  weight  of  material  occupied 
at  the  time  of  experiment  is  next  corrected  for  temperature  (to  0*^0.) 
and  pressure  (760  millimetres)  in  the  manner  just  described.  The 
weight  of  a similar  volume  of  hydrogen  is  nextfound.t  The  weights  ^ 
of  equal  volumes  of  hydrogen  and  vapor  being  thus  determined,  the  I 
amount  of  vapor  corresponding  to  1 of  hydrogen  (the  specific  gravity  j 

* Corrected  for  the  difference  between  the  mercurial  and  air  ther-  ( 
mometers  the  coefficient  of  expansion  of  air  is  0.003656  (Miller),  f 
Gases  vary  slightly.  | 

f 1 cub.  centim.  of  air  at  0°  C.  and  760  millims.  weighs  0.001293  * 
gramme.  I 

t 1 litre  (1000  cub.  centims.)  of  hydrogen  at  0°  C.  and  760  milli-  f 
metres  (the  barometer  being  at  OOC.)  weighs  0.0896  gramme — a vol-  ^ 
ume  sometimes  termed  a crith  (from  krithe^  a barley-corn— figu-  i; 

ratively,  a small  weight)  ; thus  a litre  of  oxygen  weighs  16  criths,  \i 
chlorine  35  5 criths,  etc.  100  cubic  inches  of  hydrogen  at  320  p,  j| 
weigh  2.265  grains;  at  600  p.  2.143  grains  (the  barometer  being  30  j‘ 
ins.  at  600  p.  in  both  cases).  100  cubic  inches  of  air  at  320  F.  weigh 
32.698  grains  ; at  600  p , 30  935  (barom.  30  ins  at  600  p ).  i cubic  ( 
inch  of  water  weighs  252.5  (252.458  at  620  F , and  30  in  bar.)  grains. 

1 gallon  of  water  contains  2771  (277,274  at  620  p ) cubic  inches.  : 


SPECIFIC  GRAVITY. 


ill 


or  vapor-density)  is  shown  by  a short  calculation.  This  process  of 
finding  the  weight  of  a given  volume  of  vapor  is  by  Dumas.  Gay- 
Lussac's  consists  in  determining  the  volume  of  a given  weight. 

Experiment  shows  that  the  specific  gravities  of  many  gases  and 
vapors  on  the  hydrogen  scale  and  the  proportions  in  which  they  com- 
bine by  weight  are  identical.  Thus,  chlorine  is  35.5  times  as  heavy 
as  hydrogen,  and  35.5  parts  unite  with  1 of  hydrogen  to  form  hydro- 
chloric acid  gas.  Hence,  if  the  specific  gravity  of  a gas  or  vapor  is 
known,  its  combining  proportion  may  be  predicated  with  reasonable 
certainty,  and  vice  versa.  In  applying  this  rule  to  gaseous  or  vapor- 
ous compounds,  attention  must  be  paid  to  the  extent  to  which  their 
constituent  gases  contract  *at  the  moment  of  combination  or  expand 
at  the  moment  of  decomposition.  Thus,  steam  is  found  to  be  com- 
posed of  two  volumes  of  hydrogen  and  one  of  oxygen,  the  three  vo- 
lumes of  constituents  condensing  to  two  at  the  moment  of  combina- 
tion. Hence,  steam  may  be  expected  to  be  nine  times  as  heavy  as 
hydrogen,  which  experiment  confirms. 

These  relations  may  be  so  expressed  as  to  include  both  elementary 
and  compound  gases  and  vapors,  thus : molecular  weights  and  spe~ 
cific  weights  are  identical.  Molecular  weights  represent  two  vo- 
lumes of  a gas ; specific  gravity  conventionally  represents  the  relative 
weight  of  a gas  compared  with  one  volume  of  hydrogen  or  air ; hence 
the  specific  gravity  of  a gas  or  vapor  on  the  H scale  is  found  by  cal- 
culation on  simply  dividing  the  molecular  weight  by  2 ; on  the  air- 
scale  by  dividing  the  hydrogen  numbers  by  14.44.  For  example, — 


Molecular 

Name.  formula. 

Hydrogen,  H^ 

Chlorine,  Cl.^ 

Oxygen,  O.^ 

Nitrogen, 

Steam,  H.^0 

Ammonia  gas,  NHg 

Carbonic  acid  gas,  CO.^ 
Alcohol  (vapor), _ C.^H^O 
Air,  


Molecular 

weight. 

H=2. 

2 

2 

71 

71 

32 

32 

28 

28 

18 

18 

17 

17 

44 

44 

46 

46 

28.88 

Specific  gravity. 


H = 1. 

Air  = 1. 

1 

.069 

35.5 

2.460 

16 

1.108 

14 

.970 

9 

.624 

8.5 

.589 

22 

1.524 

23 

1.593 

14.44 

1.000 

These  specific  gravities  closely  correspond  with  those  obtained  by 
actual  experiment.  The  specific  gravity  of  any  gas  or  vapor  may 
therefore  be  calculated  if  the  following  data  are  at  hand : [a)  for- 
mula, (&)  atomic  weight  of  constituent  elements ; these  give  the 
molecular  weight,  and  the  molecular  weight  divided  hy  2 is  the 
specific  gravity  on  the  hydrogen-scale.  Specific  gravity  on  the  air- 
scale  is  then  deducible,  if  (c)  the  specific  gravity  of  air  (14.44)  in 
relation  to  hydrogen  be  remembered.  The  absolute  weight  of  any 
volume  of  a gas  or  vapor  on  the  metric  system  is  then  obtainable  if 
[d]  the  weight  of  a litre  of  hydrogen  (0.0896  gramme)  be  known,  or 
on  the  English  plan  by  remembering  (e)  that  100  cubic  inches  of 
hydrogen  at  60^  F.  weigh  2.143  grains  (100  cubic  inches  of  air  at 
60^  F.  weigh  30.935  grains). 

In  confirmation  of  these  statements  regarding  the  mutual  relation 


472 


QUANTITATIVE  ANALYSIS. 


of  specific  gravity  and  atomic  weight,  a remarkable  fact  may  be 
mentioned.  Eegnault  several  years  ago  found  the  weights  of  1 litre 
of  hydrogen  and  oxygen  to  be  respectively  .089578  and  1.429802 
gramme.  The  latter  number  divided  by  the  former  gives  15.96  as 
the  specific  gravity  of  oxygen.  Stas,  in  recent  experimental  researches 
on  combining-proportion,  finds  the  atomic  weight  of  oxygen  to  be  not 
16,  but  15.96. 

Exceptions  to  the  law  occur  in  a few  compounds  and  in  arsenicum 
and  phosphorus,  whose  vapor-densities  are  twice  that  indicated  by  i 
the  rule.  | 

Relation  of  the  Specific  Heat  of  Elements  to  their  Atomic  j 
Weights. — Eeference  may  here  appropriately  be  made  to  a physical  i 
fact  of  great  importance  as  regards  molecular  and  atomic  weights.  I 
In  the  earlier  pages  of  this  manual  it  was  stated  that  elements  do  not  j 
combine  chemically  in  haphazard  proportions,  but  in  fixed  weights ; ^ 
and  abundant  evidence  of  the  truth  of  the  statement  has  already  been  ! 
afforded,  and  will  also  be  found  in  this  section  on  quantitative  analysis.  : 
Secondly,  it  has  been  shown  that  elements  do  not  combine  in  hap-  ■ 
hazard  proportions  by  volume,  but  in  certain  constant  bulks ; and  ' 
the  weights  of  these  bulks  have  been  found  to  be  identical  with  the  ; 
combining  weights  themselves.  Thirdly  (and  this  is  the  point  to  ; 
which  attention  is  drawn),  if  equal  amounts  of  heat  be  given  to  ele- 
ments in  the  solid  state  (that  is,  to  solid  elements  or  solid  compounds  i 
of  volatile  elements),  and  the  quantity  of  the  element  be  increased  or 
diminished  until  each  is  thus  heated  through  an  equal  number  of  de-  | 
grees,  it  will  be  found  that  the  different  weights  of  elements  required  i 
are  (in  relation  to  a common  standard)  identical  with  the  combining  ; 
weights  of  the  elements,  and  with  the  weights  of  the  combining  vol- 
umes  of  the  elements.  Thus,  where  108  parts  of  silver  would  be  em-  ; 
ployed,  207  of  lead  would  be  necessary.  Hence,  in  the  determination  ' 
of  (a)  combining-proportion,  (b)  specific  gravity  in  gaseous  state,  and 
(c)  specific  heat,  three  distinct  methods  of  ascertaining  atomic  weight 
are  available.  In  cases  where  one  method  is  inapplicable  recourse  is 
had  to  either  or,  if  practicable,  both  of  the  others,  and  thus  the  trust- 
worthiness of  observations  and  generalizations  placed  more  or  less  ^ 
beyond  question.  The  specific  heat  of  a solid  dementis  the  same  in  > 
the  free  as  in  the  combined  condition ; therefore  the  specific  heat  of  \ 
a molecule  is  the  sum  of  the  specific  heats  of  its  constituent  atoms.  } 
From  the  specific  heat  of  a solid  compound  of  a volatile  element  (chlo-  t 
rine,  for  example)  can  thus  be  calculated  the  specific  heat  of  an  ele-  ! 
ment  in  the  solid  state,  even  though  the  free  element  cannot  itself  be  | 
solidified.  For  the  processes  by  which  experimentally  to  determine  j 
specific  heat  the  reader  is  referred  to  books  on  physics. 


QUESTIONS  AND  EXEECISES. 

971.  Define  specific  weight,  or  as  it  is  commonly  termed,  specific  | 

gravity.  ! 

972.  In  speaking  of  light  and  heavy  bodies  especially,  what  stand-  ' 
ard  of  comparison  is  conventionally  employed  ? 


QUESTIONS  AND  EXERCISES. 


473 


973.  How  are  specific  gravities  expressed  in  figures  ? 

974.  Why  should  specific  gravities  be  taken  at  one  constant  tem- 
perature ? 

975.  How  does  the  buoyancy  of  air  affect  the  real  weight  of  any 
material  ? 

976.  Describe  the  difference  between  density  and  specific  gravity. 

977.  Give  a direct  method  for  the  determination  of  the  specific 
gravity  of  liquids. 

978.  A certain  bottle  holds  150  parts,  by  weight,  of  water,  or 
135.7  of  spirit  of  wine;  what  is  the  specific  gravity  of  the  latter? 
Ans.  0.9046. 

979.  Equal  volumes  of  benzol  and  glycerine  weigh  34  and  49  parts 
respectively,  and  the  sp.  gr.  of  the  benzol  is  0.850 ; what  is  the  spe- 
cific gravity  of  the  glycerine  ? Ans.  1.225. 

980.  Explain  the  process  employed  in  taking  the  specific  gravity 
of  solid  substances  in  mass  and  in  powder. 

981.  State  the  method  by  which  the  specific  gravity  of  a light  body, 
such  as  cork,  is  obtained. 

982.  What  modifications  of  the  usual  method  are  necessary  in 
ascertaining  the  specific  gravity  of  substances  soluble  in  water? 

983.  How  is  the  specific  gravity  of  gases  determined  ? 

984.  By  what  law  can  the  volume  of  a gas,  at  any  required  pres- 
sure, be  deduced  from  its  observed  volume  at  another  pressure  ? 

985.  To  what  extent  will  78  volumes  of  a gas  at  29.3  inches  ba- 
rometer alter  in  bulk  when  the  pressure,  as  indicated  by  the  barometer, 
is  30.2  inches  ? 

986.  Write  a short  account  of  the  means  by  which  the  volumes  of 
gases  are  corrected  for  temperature. 

987.  At  the  temperature  of  15^  C.  40  volumes  (litres,  pints,  ounces, 
cubic  feet,  or  other  quantity)  of  a gas  are  measured.  To  what  ex- 
tent will  this  amount  of  gas  contract  on  being  cooled  to  the  freezing- 
point  of  water  (0^  C.)  ? 

Ansiver.  As  1 vol.  of  any  gas  at  zero  expands  or  contracts  .003665 
of  a vol.  for  each  rise  or  fall  of  1^  C.,  1 vol.  at  0°  C.  if  heated  to  15^ 
C.  will  become  increased  by  .054975  (that  is  .003665  multiplied  by 
15),  1 vol.  will  expand  to  1.054975.  Conversely,  1.054975  vol.  will 
contract  to  1 vol.  if  cooled  from  15^  C.  to  0*^  0.  And  if  1.054975 
becomes  1 in  cooling  through  15^  C.,  40  vols.  will  (as  found  by  rule- 
of-three)  contract  to  37.916. 

(The  following  five  problems  and  solutions  are  from  Williamson’s 
“ Chemistry.”) 

988.  10  litres  of  oxygen  are  measured  off*  at  14^  F.  Kequired  the 
volume  of  the  gas  at  15^  C. 

Answer.  The  first  operation  must  be  to  reduce  the  temperature 
quoted  in  Fahrenheit’s  degrees  to  an  equivalent  value  on  the  Centi- 
grade scale.  14^  F.  is  18^  below  32°  F.,  the  freezing-point  of  water ; 
and  a range  of  9°  on  khe  Fahrenheit’s  scale  is  equal  to  a range  of  5^ 
on  the  Centigrade  scale,  so  that  the  temperature  at  which  the  oxygen 
is  measured  off  is — 10^  C.  The  rise  of  temperature  up  to  0^  expands 
the  gas  in  such  proportion  that  its  volume  at  0^  is  to  its  volume  at 
—10'^  as  1 is  to  1 — 0.03665,  ^.  e.  as  1 to  0.96335.  The  further  rise 

40* 


414: 


QUANTITATIVE  ANALYSIS. 


of  temperature  from  0^  C.  to  15^  expands  the  gas  in  the  proportion 
of  1 to  1-1-15x0.003665;  t,  e.  1 to  1.054975.  4’he  total  rise  of  tem- 
perature therefore  expands  the  gas  in  the  proportion  of  0.96335  to 
1.054975. 

0.96335  : 1.054975  : : 10  : x; 

10  X 1.054975 
^ ~ 0.96335  ~ 


989.  230  cubic  centimetres  of  oxygen  are  measured  off  at  14^  C. 
and  740  millimetres  mercurial  pressure.  Eequired  the  volume  of  the 
gas  at  the  normal  temperature  and  pressure  (0*^0.  and  760  millime- 
tres). 

Ansiuer.  Let  the  reduction  for  change  of  temperature  be  made 
first.  The  proportion 


gives 


1 -L  14  X 0.003665  : 1 ::  230 


230 

1.05131 


218.774 


To  reduce  this  volume  at  740  millimetres  pressure  to  the  volume  i 
corresponding  to  the  pressure  of  760  millimetres,  we  have  the  pro-  j 
portion 

38  :37  ::  218.77  :x; 

whence 


X = 


37  X 218.77 
38 


213.02. 


990.  A litre  of  oxygen  is  confined  in  a glass  flask  at  10^  0.  by  the  ; 
atmospheric  pressure,  added  to  that  of  a column  of  mercury  60  milli-  • 
metres  high.  The  flask  must  be  heated  to  300^  C.  without  any  in-  * 
crease  of  volume  taking  place  in  the  oxygen.  How  high  must  the  * 
column  of  mercury  then  be  which  presses  on  the  gas,  supposing  the  ' 
atmospheric  pressure  to  remain  constant  at  760  millimetres  ? 

Anstver.  The  oxygen  is  given  at  10^  0.  and  820  millimetres  , 
pressure.  If  the  pressure  remained  constant,  the  rise  of  temperature  i 
from  10^^  0.  to  300*^  G.  would  expand  the  gas  in  such  proportion  that  : 

1.03665  volume  would  expand  to  2.0995  volumes.  In  order  to  pre- 
vent any  expansion  the  pressure  must  be  increased  in  the  same  pro- 
portion, whence 

1.03665  : 2.0995  : : 820  : x; 


820  X 2.0995 

1.03665  ~ 


1660.6. 


From  this  total  pressure  the  atmospheric  pressure  of  760  millimetres 
has  to  be  deducted,  leaving  900.6  millimetres  as  the  height  of  the 
required  mercurial  column.  ! 

991.  A litre  of  oxygen  is  required  of  the  density  of  100  at  0^  C.  ‘ 
What  weight  of  potassic  chlorate  must  be  used  for  its  preparation, 
and  what  total  pressure  must  be  applied  to  it  ? 

Ansxoer.  The  pressure  required  to  compress  oxygen  froin  the  den- ; 
sity  of  16  to  that  of  100  is  found  by  the  proportion 


VOLUMETRIC  ANALYSIS. 


475 


16  : 100  : : 760  :x; 

76000 

X = ~T7r-  = 4750. 

Id 

At  the  pressure  of  4750  millimetres  of  mercury  the  weight  of  a litre 
of  oxygen  (16  grammes  measure  11.2  litres  at  0^  0.  and  760  millims. 
pressure)  is  found  by  the  proportion 

760  :4750  : : : x ; 

11.2  ' 

whence 

— X 4<50  _ g grammes. 

^■“  11.2  x 760  ^ 

The  weight  of  chlorate  required  for  the  evolution  of  8.93  grammes 
of  oxygen  is  found  from  the  proportion 

48  : 122.5  : : 8.93  :x; 

.\x=22.S  grammes. 

992.  What  is  the  volume  of  12  grammes  of  hydrogen  at  15^  C.  ? 
Answer.  One  gramme  of  hydrogen  measures  11.2  litres  at  0^  C., 

therefore  12  grammes  measure  12  X 11.2  = 134.4  litres  at  0^.  To  find 
their  volume  at  1.5^  C.  we  have  the  proportion 

1 : 1 + 15  X 0.003665  : : 134.4  : x; 

whence 

ir=134.4  X 1.054975  = 141.788  litres. 

993.  What  interest  for  chemists  have  the  specific  heats  of  sub- 
stances ? • 


VOLUMETRIC  ANALYSIS. 

{See  the  Introductory  Remarlcs  to  Quantitative  Analysis.) 

APPARATUS. 

The  only  special  vessels  necessary  in  volumetric  quantitative  ope- 
rations are  \ 1.  A litre  flask,  which,  when  filled  to  a mark  on  the 
neck,  contains  one  litre  (1000  cubic  centimetres,  i.  e.,  1000  grammes 
of  water*) ; it  serves  for  preparing  solutions  in  quantities  of  one 
litre.  2.  A tall,  cylindrical  graduated  litre  jar  divided  into  100 
equal  parts ; it  serves  for  the  measurement  and  admixture  of  deci- 
mal or  centesimal  parts  of  a litre.  3.  A graduated  tube  or  burette, 
which,  when  filled  to  0,  holds  100  cubic  centimetres  (a  decilitre),  and 

* A cubic  centimetre  is,  strictly  speaking,  the  volume  occupied  by 
one  gramme  of  distilled  water  at  its  point  of  greatest  density,  namely, 
40  C.  ; metrical  measurements,  however,  are  uniformly  taken  at 
150.55  C.  (600  F.). 


476 


QUANTITATIVE  ANALYSIS. 


is  divided  into  100  equal  parts ; it  is  used  for  accurately  measuring 
small  volumes  of  liquids. 

The  best  form  of  a burette  is  Mohr’s.  It  consists  of  a glass  tube 
about  the  width  of  a little  finger  and  the  length  of  an  arm  from  the 
elbow,  contracted  at  the  lower  extremity  and  graduated.  To  the 
contracted  portion  is  fitted  a small  piece  of  vulcanized  caoutchouc 
tubing,  into  the  other  end  of  which  a small  spout  made  of  narrow 
glass  tube  is  tightly  inserted.  A strong  wire  clamp  effectually  pre- 
vents any  liquid  from  passing  out  of  the  burette  unless  the  knobs  of 
the  clamp  are  pressed  by  the  finger  and  thumb  of  the  operator,  when 
a stream  or  drop  flows  at  will.  The  accurate  reading  of  the  height 
of  a solution  in  the  burette  is  a matter  of  great  importance  ; it  should 
be  taken  from  the  bottom  of  the  curved  surface  of  the  liquid.  It 
may  be  still  more  exactly  measured  in  operations  of  special  delicacy 
by  the  employment  of  a hollow  glass  float  or  bulb  (Erdmann’s  float), 
of  such  a width  that  it  can  move  freely  in  the  tube  without  undue 
friction,  and  so  adjusted  in  weight  that  it  shall  sink  to  more  than 
half  its  length  in  any  ordinary  liquid.  A fine  line  is  scratched  round 
the  centre  of  the  float ; this  line  must  be  always  regarded  as  marking 
the  height  of  the  fluid  in  the  burette.  In  charging  the  burette,  a 
solution  is  poured  in,  not  until  its  surface  is  coincident  with  0,  but 
until  the  mark  on  the  float  is  coincident  with  0. 


ESTIMATION  OE  ALKALIES,  ETC. 

An  equation  represents  much  more  than  the  formation  of  certain 
substances  from  others.  Thus 

2NH,HO  + H^C^O,,  2H,0  = (NHJ^O^O^,  H,0  + SH^O 

Amraouia.  Crystallized  Oxalate  of  Water, 

oxalic  acid.  ammonium. 

not  only  shows  that  oxalate  of  ammonium  is  produced  when  ammo- 
nia and  crystallized  oxalic  acid  are  mixed  together,  but  among  other 
facts,  that  70  parts  of  ammonia  and  126  of  oxalic  acid  yield  142  of 
crystallized  oxalate  of  ammonium  and  54  of  water.  For  formulae 
represent  molecules ; the  weight  of  a molecule  is  the  sum  of  the 
weights  of  atoms  ; and  atomic  weights  are  represented  by  definite  in- 
variable numbers  (see  the  Table  of  atomic  weights  in  the  Appendix). 

As  126  parts  (=  I molecule)  of  oxalic  acid  combine  with  70  parts 
(=  2 molecules)  of  ammonia,  63  (half  of  126)  of  oxalic  acid  will 
unite  with  35  (=  ] molecule)  of  ammonia  (NH^HO);  63  parts  of 
oxalic  acid  will  also  unite  with  56  of  caustic  potash  (KHO  = 56),  40 
of  caustic  soda  (NaHO=40),  100  of  acid  carbonate  of  potassium 
(KIIC0.5==  IOO),  69  of  anhydrous  carbonate  of  potassium  (K2C03  = 
138),  84  of  acid  carbonate  of  sodium  (NaHC03  = 84),  53  of  anhy- 
drous carbonate  of  sodium  (Na2C03=  106),  or  143  of  crystallized 
carbonate  of  sodium  (Na^OO-p  lOH.^O  ==  286).  And  if  63  parts  of 
oxalic  acid  be  dissolved  in  100  volumes  of  water,  the  stated  weights 
of  these  various  salts  should  be  exactly  neutralized  by  such  a solu- 
tion. 143  parts  of  crystallized  carbonate  of  sodium,  for  instance, 


VOLUMETRIC  ESTIMATION  OF  ALKALIES.  477 

should,  if  pure,  be  exactly  neutralized  by  the  100  volumes  of  the 
oxalic  acid  solution  ; and  if  a less  number  of  volumes  is  required,  the 
salt  is  so  much  per  cent,  impure.  143  parts  by  weight  of  a commer- 
cial sample  of  carbonate  of  sodium  (common  washing  “soda”)  re- 
quiring only  97  of  the  standard  oxalic  acid  solution  is  thus  shown  to 
contain  97  per  cent,  of  pure  carbonate  of  sodium,  the  remainder 
being  impurities.  Further,  the  strength  of  solutions  of  ammonia, 
soda,  potash,  and  lime  may  be  accurately  determined  by  adding  to 
any  definite  quantity  of  them  gradually,  from  a burette,  a solution 
containing  oxalic  acid  in  known  quantity,  until  exact  neutralization 
is  effected.  If  the  quantity  of  oxalic  acid  required  be  63  parts  by 
weight  (or  100  volumes  of  solution  of  oxalic  acid  containing  63 
parts,  by  weight,  of  the  crystals),  then  the  quantities  of  alkaline  so- 
lutions employed  contain,  of  potash  (KHO)  56  parts  by  weight,  of 
soda  (NaliO)  40,  of  ammonia  (NH^IIO)  35  parts,  of  slaked  lime 
(Ca2HO)  37,  anhydrous  lime  (CaO)  28,  etc.  The  strength  of  an 
alkaline  solution,  or,  in  other  words,  the  proportion  required  to  effect 
neutralization  of  100  volumes  of  the  oxalic  acid  solution,  having  once 
been  determined  and  decided  by  authority  (B.  P.  e,  g.),  that  quantity 
may  always  be  expected  to  take  100  volumes  of  the  oxalic  acid  liquid  ; 
if  less  is  required,  the  alkaline  liquid  is  so  much  per  cent.  weak. 

The  exact  point  of  neutralization  of  acid  or  alkaline  liquids  is  ex- 
perimentally ascertained  by  litmus  paper,  or,  more  generally,  infusion 
of  litmus,  which  is  turned  red  by  the  slightest  amount  of  free  acid, 
and  blue  by  alkali. 

Standard  Solution  op  Oxalic  Acid. 

(Crystallized  Oxalic  Acid,  H^C.^O^,  2H20=126.) 

On  account  of  the  bivalent  character  of  the  oxalic  radi- 
cal and  the  univalent  character  of  most  of  the  metals 
contained  in  the  salts  which  are  estimated  by  oxalic  acid, 
it  is  convenient  to  take  half  the  molecular  weight  of  the 
acid  for  experiments,  with  the  whole  of  the  molecular 
weights  of  salts  of  univalent  basylous  radicals.  Tlie 
oxalic  acid  must  be  pure,  leaving  no  ash  when'  a gramme 
or  so  is  heated  to  redness  in  a porcelain  or  platinum  cruci- 
ble; it  must  also  be  quite  dry,  but  not  effloresced. 

Place  63  grammes  of  the  crystals  in  a litre  flask,  add 
distilled  water  and  shake  till  dissolved,  diluting  until  the 
solution,  at  about  60°  F.,  has  an  exact  volume  of  1 litre. 
Preserve  in  a stoppered  bottle. 

100  cubic  centimetres  of  this  solution  contain  of  the 
molecular  weight  of  oxalic  acid  in  grammes,  and  will 
neutrallize  of  the  molecular  weight  in  grammes,  of  a 
salt  containing  one  atom  of  certain  bivalent  metals  (as 
Ca2lIO),  or  a salt  (Na^CO^  e.  g.)  containing  two  atoms  of 
univalent  metals,  or  of  the  molecular  weight  in  grammes 


478 


QUANTITATIVE  ANALYSIS. 


of  salts  containing  one  atom  of  univalent  radicals  (such  as 
KHCO3). 

The  following  official  substances  are  tested  with  this 
solution.  In  those  which  are  fluid  there  is  commonly  a 
slight  variation  in  strength  according  as  they  are  made  by 
formulae  of  the  British  or  U.  S.  Pharmacopoeia. 

Grammes  of  C.  c.  of 

substance.  vol.  sol. 


* Ammonia,  solution  of 17.00  = 

“ strong  solution  of 5.23  = 

Ammonium,  carbonate  of,  B.  P.  and  U.  S.  P.  5.90  — 

Borax,  B.  P.  and  U.  S.  P 19.10  = 

Lead,  acetate  of,  B.  P.  and  U.  S.  P.  . . 9.50  = 

“ sol.  of  subacetate  of,  B.  P.  and  U.  S.  P.  51.02  = 
Lime,  aqueous  solution  of,  B.  P.  and  U.  S.  P.  438.00  = 

“ saccharated  sol.  of, 45.30  = 

Potash,  caustic,  B.  P.  and  U.  S.  P.  . . . -5.60  = 

“ solution  of 48.02  = 

“ water,  effervescing 292.00  = 

Potassium,  bicarbonate  of,  B.  P.  and  U.  S.  P.  5.00  = 

“ acid  tart,  of,  B.  P.  and  U.  S.  P.  18.80  = 

“ carbonate  of,  B.  P.  and  U.  S.  P.  8.30  = 

“ citrate  of,  B.  P.  and  U.  S.  P.  . 10.20  = 

“ tartrate  of,  B.  P.  and  U.  S.  P.  . 11.30  = 

Soda,  caustic,  B.  P.  and  U.  S.  P 4.00  = 

“ solution  of 48.72  = 

“ water,  effervescing  246.07  = 

Sodium,  bicarbonate  of,  B.  P.  and  U.  S.  P.  8.40  = 
“ and  potassium,  tart,  of,  B.P.  and  lT.S.P.14.10  = 

“ carbonate  of,  B.  P.  and  U.  S.  P.  . 14.30  = 


100.0 

100.0 

100.0 

100.0 

50.0 
100.0 

20.0 

25.0 

90.0  to  100.0 

50.0 

10.0 
50.0 

100.0 

98.0  to  100.0 

100.0 

100.0 

90.0  to  100.0 

50.0 

10.0 
100.0 
100.0 

96.0  to  100.0 


Note  1. — The  several  substances  diluted  or  dissolved,  as  described 
in  the  following  paragraphs,  are  conveniently  placed  in  a beaker, 
and  the  solution  of  acid  run  in  cautiously  from  the  brunette. 

Note  2. — A smaller  number  of  c.  c.  of  volumetric  solution  than 
100,  and  a corresponding  amount  of  substance  to  be  tested,  may  be 
employed  in  any  case.  But  to  ascertain  percentage  of  impurity  in 
the  substance,  the  amount  corresponding  to  100  c.  c.  of  the  vol.  sol. 
must  be  considered  to  have  been  used,  the  number  of  c.  c.  then 
wanting  to  make  up  100  is  the  percentage  of  impurity. 

The  solutions  of  ammonia  require  only  the  addition  of 
solution  of  litmus,  and  the  acid  cautiously^  added  until  the 
last  drop  turns  the  liquid  red.  The  amount  of  acid  used 
previously  to  the  addition  to  the  portion  that  reddened 
the  litmus  indicates  the  proportional  purity  of  the  alkaline 
liquid.  Thus,  if  only  50  c.  c.  are  requirecT,  the  solution  is 


* The  reading  of  the  Table  maybe  amplified  thus:  17  grammes 
of  the  official  Solution  of  Ammonia  ( AwV/uor  B.  P.),  carefully 

weighed,  will  require,  for  complete  neutralization,  if  of  full  strength, 
100  cubic  cemtimetres  of  the  official  volumetric  solution  of  oxalic  acid. 


VOLUMETRIC  ESTIMATION  OF  ALKALIES.  479 

only  half  as  strong  as  it  ought  to  he  ; if  93  c.  c.  are  needed, 
the  sol.  of  ammonia  is  7 per  cent,  too  weak,  and  so  on. 
The  actual  quantity  of  ammonia  (NH^HO)  or  ammoniacal 
gas  (NH3)  in  the  solutions  is  readily  ascertained  by  calcu- 
lations, thus:  100  c.  c.  of  the  acid  solution  have  been  em- 
ployed ; these  contain  2V  molecular  weight  of  oxalic 

acid  in  grammes=6.3,  and  have  neutralized  of  the  mo- 
lecular weight  of  ammonia  in  grammes  = 3.5  (or  1.7  of  NH3) ; 
5.23  parts,  by  weight,  of  strong  solution  of  ammonia  (the 
amount  employed  in  the  experiment)  contain,  therefore, 
3.5  of  ammonia,  NH^HO,  or  1.7  of  ammoniacal  gas  NH.^; 
now  if  5.23  parts  of  a solution  contain  3.5  of  real  ammonia 
(NH4HO),  100  parts  will  contain  (by  riile-of-three  calcula- 
tion) 67,  and  if  the  5.23  contain  1.7  part  of  ammonia  gas 
(NH3),  100  will  contain  32.5 ; hence  the  Strong  Solution  of 
Ammonia,  supposed  to  have  been  under  examination,  con- 
tains 67  per  cent,  of  the  hydrate  or  32.5  per  cent,  of  the 
gas.  The  formulae  and  molecular  weights  representing 
this  process  are  as  follows  : — 

2NH,HO  (or  2NH3)  H,C^O,,2H,0 

70  34  126 

The  carhonate  of  ammonium  should  be  dissolved  in  30 
or  40  c.  c.  of  distilled  water,  infusion  of  litmus  added,  the 
standard  oxalic  acid  solution  allowed  to  flow  in  until  the 
well-stirred  liquid  assumes  a purple  hue  (due  to  the  in- 
fluence of  carbonic  acid  on  the  litmus),  the  whole  gently 
warmed  to  promote  evolution  of  carbonic  acid  gas,  more 
standard  acid  then  dropped  in  until  the  liquid  again  be- 
comes purple,  heat  once  more  applied,  and  the  operation 
continued  until  the  last  drop  of  acid  turns  the  solution 
red;  the  height  of  the  column  of  liquid  in  the  burette 
before  the  last  drop  escapes  represents  the  true  amount  of 
standard  solution  used,  and  hence  the  percentage  of  real 
carbonate  of  ammonium  (of  ofiicial  quality)  in  the  specimen 
on  which  the  experiment  was  performed.  The  solution 
must  be  heated  with  care,  or  ammonia  will  escape.  (Prac- 
tised analysts  usually  add  excess  of  the  standard  acid  and 
thus  flx  every  trace  of  ammonia ; then  gently  boil  to  get 
rid  of  carbonic  acid  gas  ; bring  back  the  liquid  to  neutrality 
by  an  observed  volume  of  standard  alkaline  solution,  and 
deduct  an  equivalent  volume  of  acid  from  the  quantity  first 
added.)  The  formulae  and  molecular  weights  representing 
the  process  are  as  follows : — 


480 


QUANTITATIVE  ANALYSIS. 


N,H.„C30,  + 2(II,C30„2H,0) 

V ^ s ^ 

236  252 

{vide  p.  78)  (2  molecules) 

As  252  parts  of  oxalic  acid  neutralize  236  of  the  so-called 
carbonate  of  ammonium,  6.3  of  acid  (or  100  vols.  of  its 
solution)  will  neutralize  5.9  of  carbonate.  If  5.9  grammes 
of  carbonate  be  the  quantity  emplo3^ed,  and  it  does  not 
require  100  c.c.  of  the  volumetric  solution,  it  is  so  much 
per  cent.  weak.  Thus,  if  say  94  c.  c.  neutralize  the  salt, 
the  latter  is  6 per  cent.  Tveak  (some  ammonia  gas  has 
escaped,  and,  consequently,  an  abnormal  amount  of  acid 
carbonate  NH^HCO..,  is  present).  Any  smaller  quantity 
of  salt  than  5.9  grammes  may  be  used  ; in  that  case  a rule-  | 
of-three  sum  must  be  worked  to  show  how  many  c.c.  of  i 
vol.  sol.  would  have  been  employed  if  5.9  grammes  had  i 
actually  been  the  amount  under  experiment. 

The  borax  should  be  dissolved  in  several  ounces  of  dis- 
tilled water.  The  formulae  and  molecular  weights  repre- 
senting the  process  are  as  follows : — 

2NaBO„BA,10H,O  + 


382  126 

The  solutions  of  the  acetates  of  lead  in  distilled  water  i 
may  be  rendered  clear  by  the  addition  of  a few  drops  of 
acetic  acid.  They  must  be  well  stirred  after  each  addition  i 
of  the  solution  of  oxalic  acid.  The  action  is  complete 
when  the  last  drojj  of  acid  produces  no  more  precipitate 
(oxalate  of  lead). 


Pb2C,H,0„  3H.p  + 2H,0 


Pb.p2C,H30.,  + 2(H,C,0,,  2H,0) 


548  252 

The  solutions  of  lime  require  similar  treatment. 


Ca2HO  (or  CaO)  -f  2H.,0 


Solid  caustic  2^otash  or  soda  is  never  met  with  in  a state 
of  chemical  purity,  but  should  contain  not  less  than  90  per 
cent,  of  the  hydrate  of  potassium  or  sodium.  The  stand- 
ard acid  is  added  to  an  aqueous  solution  of  the  hydrate, 


VOLUMETRIC  ESTIMATION  OF  ALKALIES.  481 


tlie  termination  of  the  action  between  the  alkali  and  acid 
being  observed  by  aid  of  litmus. 

If  carbonic  acid  be  present,  the  mixture  must  be  gently 
boiled  before  a final  reading  of  the  amount  of  acid  added 
is  taken. 


2KHO  or  2]S'aHO  + 2H,0 

112  80  126 


The  alkaline  carbonates  are  often  moist,  and  include 
traces  of  sulphates,  chlorides,  and  silicates,  but  are  suffi- 
ciently pure  if  containing,  in  the  case  of  carbonate  potas- 
sium 98  per  cent.,  and  carbonate  of  sodium  96  per  cent.,  of 
the  respective  crystalline  salts.  The  volumetric  manipula- 
tions with  these  salts  are  similar  to  those  for  carbonate  of 
ammonium.  The  strength  of  soda-ash  is  often  reported 
in  terms  of  “soda,’’  that  is,  oxide  of  sodium  (Na20  = 62). 
The  old  molecular  weight  of  carbonate  of  sodium,  54  (it 
should  have  been  53),  derived  from  that  of  “ soda,”  32  (it 
should  have  been  31),  is  still  employed  in  Great  Britain  in 
reporting  the  strength  of  soda-ash.  The  true  amount  of 
soda  equivalent  to  54  parts  of  carbonate  is  31.41  parts.  A 
modern  analyst  having  found  the  true  amount  of  soda  in 
a sample  of  soda-ash  is  expected  by  some  manufacturers 
to  report  31.41  parts  for  every  31,  and  54  of  carbonate 
instead  of  53,  and  other  quantities  in  proportion  to  these 
figures. 


2KHCO3  -f  2H,0 


2NaHC03  + II,C,0„  2H,0 


200  126 

K,C03  + II,CA,2H,0 


138  126 


168  126 

Na,^3  + 

106  126 


K,C03  of  84%4-HA04,  2H,0 

16Tr285  126 


Nu.CO,,  1QH,0  +H,OA,2H,0 


286 


126 


One  molecule  of  tartrate  of  potassium^  or  two  of  the  acid 
tartrate^  yields  one  of  carbonate  when  burnt,  two  molecules 
of  citrate  yielding  three  of  carbonate  under  the  same  cir- 
cumstances. Two  molecules  of  tartrate  of  potassium  and 
sodium  yield  one  of  potassium  carbonate  and  one  of 
sodium  carbonate.  A volumetric  estimation  of  the  amount 
of  carbonate  thus  produced  aifords  indirect  means  of  quan- 
titatively determining  the  purity  of  the  original  salts. 

41 


482 


QUANTITATIVE  ANALYSIS. 


eq.  to  2H,0 

V > V > 

226  126 
2KHC,H,0,  eq.  to  11,0,0,,  2H,0 

' y ' ' y ' 

376  126 

2K3C,H,0,  eq.  to  3H,C,0„  2H,0 

612  378 

NaKC,H,0„  4H,0  eq.  to  H,C,0„  2H,0 

' Y ' *■ V ^ 

282  126 

Alkalimetry, — The  foregoing  processes  are  often  spoken 
of  as  those  of  alkalimetry  (the  measurement  of  alkalies). 


Notes. 

Neutral  solution  of  litmus  is  prepared  by  digesting  the 
commercial  fragments  in  about  fifteen  or  twenty  times  their 
weight  of  water  for  a few  hours,  decanting,  dividing  into 
two  equal  portions,  adding  acid  to  one  till  it  is  faintly  red, 
then  pouring  in  the  other,  and  mixing.  The  solution  may 
be  kept  in  a stoppered  bottle,  but  occasionally  exposed  to 
the  air.  It  should  never  be  filtered,  but  gradually  allowed 
to  deposit. 

Standard  sulphuric  acid  may  be  used  in  the  place  of 
oxalic  acid  if  the  latter  cannot  readily  be  obtained  in  a 
state  of  purity,  100  c.  c.  of  the  liquid  containing  Aq  of  the 
molecular  weight  of  the  pure  acid  in  grammes.  It  is  pre- 
pared by  diluting  oil  of  vitriol  with  from  three  to  four  times  * 
its  bulk  of  distilled  water,  ascertaining  how  much  of  the 
acid  liquid  is  required  to  exactly  neutralize  of  the  mo- 
lecular weight  of  pure  carbonate  of  sodium,  taken  in 
grammes  (5.3),  and  adding  water  until  the  observed  volume  - 
of  acid  is  increased  to  100  c.  c.  Pure  anhydrous  carbon- 
ate of  sodium  (Na.^CO.J  is  obtained  by  heating  the  pure 
bicarbonate  to  dull  redness  in  a platinum  or  porcelain  cru- 
cible for  about  a quarter  of  an  hour.  The  commercial  ] 
bicarbonate  should  be  tested  for  chlorides  and  sulphates,, 
which  are  usually  present  in  small  quantities.  Two  or  three 
hundred  grammes  ma}"  be  purified  by  washing  first  with  a , 
saturated  solution  of  bicarbonate  of  sodium  and  then  coldi 
distilled  water  until  all  trace  of  impurity  has  disappeared,, 
drjdng  over  a water-bath,  and  then  igniting  to  convert  into . 
carbonate. 


VOLUMETRIC  ESTIMATION  OF  ACIDS. 


483 


Other  quantities  of  salts  than  those  stated  in  the  foregoing  and 
following  Tables  may  be  employed  in  volumetric  determinations,  cal- 
culation giving  any  desired  form  to  the  experimental  results,  an 
expert  analyst  thus  saving  much  time  and  material.  In  the  case  of 
substances  which  are  liable  to  alter  by  exposure  to  air,  it  is  important 
that  a selected  quantity  should  be  quickly  weighed,  rather  than 
selected  weights  be  accurately  balanced  by  material,  the  former 
operation  occupying  much  the  shorter  time. 

Salts  other  than  the  official  may  be  quantitatively  analyzed  by 
the  volumetric  solutions,  slight  modifications  of  manipulation  even 
enabling  the  processes  to  be  adapted  to  fresh  classes  of  salts.  Ample 
instructions  for  extending  operations  in  this  manner  will  be  found  in 
Sutton’s  “Handbook  of  Volumetric  Analysis.” 


QUESTIONS  AND  EXERCISES. 

994.  Describe  the  various  pieces  of  apparatus  used  in  volumetric 
deternrinations. 

995.  One  hundred  cubic  centimetres  of  solution  of  oxalic  acid  con- 
tain 6.3  grammes  of  the  crystallized  salt;  what  weights  of  bicar- 
bonate of  potassium  and  anhydrous  carbonate  of  sodium  will  that 
volume  saturate  ? — Ans.  10  grammes  and  5.3  grammes. 

996.  What  weight  of  hydrate  of  potassium  is  contained  in  solution 
of  potash  48.02  grammes  of  which  are  saturated  by  50  c.  c.  of  the 
standard  solution  of  oxalic  acid? — A7is.  5.83  per  cent. 

997.  State  the  percentage  of  hydrate  of  calcium  in  lime-water 
438  grammes  of  which  are  neutralized  by  20  c.  c.  of  the  volumetric 
solution  of  oxalic  acid. — Ans.  .1689. 

998.  Eight  grammes  of  a sample  of  Rochelle  salt,  after  appropriate 
treatment,  require  54.3  c.  c.  of  the  oxalic  acid  solution  for  complete 
saturation  ; what  is  the  centesimal  proportion  of  real  salt  present  ? — 
Ans.  95.7. 


ESTIMATION  OF  ACIDS. 

In  the  previous  experiments  a known  amount  of  an  acid  has  been 
used  in  determining  unknown  amounts  of  alkalies.  In  those  about 
to  be  described  a known  amount  of  an  alkali  is  employed  in  estimat- 
ing unknown  amounts  of  acids.  The  alkaline  salt  selected  may  be 
a hydrate  or  a carbonate  ; but  the  former  is  to  be  preferred  ; for  the 
carbonic  acid,  set  free  when  a strong  acid  is  added  to  a carbonate, 
interferes  to  some  extent  with  the  indications  of  alkalinity,  acidity, 
or  neutrality  afforded  by  litmus.  The  alkali  most  convenient  for  use 
is  soda,  a solution  of  which  has  probably  already  been  made  the  sub- 
ject of  experiment  in  operations  with  the  standard  solution  of  oxalic 
acid.  It  should  be  kept  in  a stoppered  bottle  and  exposed  to  air  as 
little  as  possible. 

Standard  Solution  of  Soda. 

(Hydrate  of  Sodium,  NaHO  = 40.) 

100  c.  c.  of  the  standard  solution  of  oxalic  acid  are 
placed  in  a beaker  with  a little  litmus,  the  tube  or  burette 


484 


QUANTITATIVE  ANALYSIS. 


in  which  the  acid  was  measured  rinsed  out,  and  the  wash- 
ings poured  into  the  beaker.  A little  strong  solution  of 
caustic  soda  is  poured  through  the  burette  to  rinse  out 
water  adhering  to  the  tube  and  float  (these  rinsings  thrown 
away),  and  the  tube  then  filled  to  0 with  more  of  the  alka- 
line liquid.  The  solution  of  soda  is  cautiously  allowed  to 
flow  into  the  beaker  until  exact  neutrality  is  obtained,  the 
quantity  noted,  and,  to  every  similar  quantity  of  the  whole 
bulk  of  the  solution  of  soda,  water  added  until  the  liquid 
measures  100  parts.  If,  for  example,  93  c.  c.  of  solution  of 
soda  have  neutralized  the  100  c.  c.  of  acid,  then  7 c.  c.  of 
distilled  water  must  be  added  to  93  c.  c.  of  the  soda  solu- 
tion, or  70  to  930  to  make  a litre.  A sum  of  simple  pro- 
portion will  show  to  what  extent  any  other  quantity  is  to 
be  diluted.  Thus,  if  the  bulk  of  soda  solution  remaining 
measures,  say,  900  c.  c.,  its  volume  must  be  augmented  to 
967.7  c.  c. ; for  if  93  are  to  be  diluted  to  100,  900  must  be 
diluted  to  967.7. 

100  c.  c.  of  the  soda  solution  contain  of  the  molecular 
weight  (=  4),  taken  in  grammes,  of  pure  hydrate  of  sodium, 
and  will  neutralize  an  equivalent  quantity  of  any  acid. 
That  is,  100  c.  c.  will  neutralize  of  the  molecular  weight 
in  grammes  of  an  acid  containing  one  atom  of  any  univ- 
alent acidulous  radical,  of  the  molecular  weight  in 
grammes  of  an  acid  containing  one  atom  of  an}^  bivalent 
acidulous  radical,  or  of  the  molecular  weight  in 
grammes  of  an  acid  containing  one  atom  of  any  trivalent 
acidulous  radical. 

The  following  official  acids  are  tested  with  this  solution  : — 

Grammes  C.  c.  of 
of  substance.  vol.  sol. 


Acid,  acetic  18.20  = 100.0 

“ “ diluted,  B.  P.  and  U.  S.  P.  70.29  = 50.0 

“ glacial 6.00  = 99.0 

“ citric,  B.  P.  and  U.  S.  P.  . . . 7.00  = 100.0 

“ hydrochloric,  B.  P.  and  U.  S.  P.  11.48  = 100.0 

‘‘  diluted  ....  34.50  = 100.0 

‘‘  nitric,  B.  P.  and  U.  S.  P.  . . . 9.00  = 100.0 

“ “ diluted 36.13  = 100.0 

“ nitro-hydrochloric,  diluted  . . . 38.30  = 100.0 

“ sulphuric,  B.  P.  and  U.  S.  P.  . 5.06  = 100.0 

“ “ aromatic 36.65  = 100.0 

“ “ diluted 35.90  ==  100.0 

“ tartaric,  B.  P.  and  U.  S.  P.  . . 7.50  = 100.0 


Notes, — 1.  In  volumetricall}^  estimating  the  strength  of 
acids  by  an  alkali,  the  indicator  of  neutrality  is  the  same 
as  that  used  in  testing  alkalies  by  an  acid,  namel}^  litmus. 


VOLUMETRIC  ESTIMATION  OP  ACIDS.  485 


2.  Pure  acetates,  citrates,  tartrates,  and  some  other  or- 
ganic salts  have  an  alkaline  action  on  litmus,  but  not  to 
an  important  extent.  If  the  soda  solution  be  added  to 
acetic,  citric,  or  tartaric  acids,  containing  litmus,  until  the 
liquid  is  fairly  blue,  the  operator  will  obtain  trustworthy 
results.  In  delicate  experiments  turmeric  may  be  used 
instead  of  litmus. 

3.  Six  grammes  of  pure  glacial  acetic  acid  are  neutra- 
lized by  100  c.  c.  of  the  standard  solution  of  soda.  But 
acid  of  this  degree  of  purity  is  extremely  difficult  to  pre- 
pare. The  commercial  acid  contains  only  1 per  cent,  of 
water,  and  is  sufficiently  pure  for  use  in  medicine. 

Acidimetry. — The  operations  for  the  quantitative  analysis  or 
measurement  of  acids  are  often  collectively  spoken  of  under  the 
name  of  acidimetry.  They  admit  of  considerable  extension.  (See 
the  work  previously  cited.) 

Percentage  strength  of  Acids. — The  percentage  strength  of  the 
several  acids  and  their  official  solutions  is  readily  ascertained  by 
calculation  in  a manner  similar  to  that  given  for  alkalies.  Thus  the 
volumetric  operation  with  the  liquid  commonly  termed  acetic  acid  is 
based  on  the  reaction  expressed  in  the  following  equation  : — 

HC,H302  + NaHO  = NaC,H302  + H^O. 

Acetic  acid.  Soda.  Acetate  of  sodium.  Water. 

This  equation,  translated  into  parts  by  weight,  means  that  60  parts 
(the  molecular  weight)  of  true  acetic  acid  are  exactly  neutralized  by 
40  parts  (the  molec.  wt.)  of  soda.  Supposing  the  quantity  of  “ acetic 
acid”  employed  in  the  experiment  to  have  been  that  recommended  in 
the  Table  (18.2  grammes),  and  that  to  neutralize  it  100  c.  c.  of  the 
soda  solution  have  been  used,  and  remembering  that  100  c.  c.  of  the 
soda  solution  contain  4 grammes  of  soda,  it  follows  that  the  18.2 
grammes  of  the  liquid  called  acetic  acid  contain  6 grammes  of  real 
acetic  acid;  for  if  40  (the  molec.  wt.)  of  soda  neutralize  60  (the 
molec.  wt.)  of  real  acetic  acid,  4 will  neutralize  6.  Lastly,  if  18.2 
contain  6,  100  will  contain  33  ; the  so-called  acetic  acid  (really  an 
aqueous  solution)  contains  33  per  cent,  of  true  acetic  acid  (HC2H3 

If  the  18.2  grammes  have  taken,  say,  93  instead  of  100  c.  c.,  the 
acid  liquid  is  7 per  cent,  weak;  in  other  words,  it  contains  only  30.7 
per  cent,  of  real  acid ; for  (by  rule-of-three)  if  100  c.  c.  added  to 
18.2  grammes  indicate  33  per  cent.,  93  c.  c.  added  to  18.2  grammes 
indicate  30.7  per  cent. 

The  remaining  acids  react  with  the  alkaline  salts  in  the  manner 
and  to  the  extent  indicated  by  the  following  formula3  and  molecular 
weights : — 

H2O  -+•  3NaHO 

41'^ 


210 


120 


486 


QUANTITATIVE  ANALYSIS. 


HCl  + NaHO 

36.5  40 

H,SO,  + 2NaHO 


98 


80 


HNO, 


NaHO 


63  40 

H.C.H.Og  + 2NaHO 


150 


80 


QUESTIONS  AND  EXERCISES. 

999.  What  percentage  of  real  acid  is  present  in  diluted  sulphuric 
acid  30  grammes  of  which  are  neutralized  by  84  c.  c.  of  the  official 
volumetric  solution  of  soda  ? — Ans.  13.72. 

1000.  How  much  real  nitric  acid  is  contained  in  a solution  36 
grammes  of  which  are  saturated  by  94  c.  c.  of  the  standard  solution 
of  soda  ? — Ans.  16.45  per  cent. 


ESTIMATION  OF  ACIDULOUS  RADICALS  PRECIPI- 
TATED BY  NITRATE  OF  SILVER. 

The  purity  of  many  salts,  and  the  strength  of  their  solutions,  may 
be  determined  by  this  process ; but  at  present  only  three  official 
substances  (namely,  diluted  hydrocyanic  acid,  bromide  of  potassium, 
and  arseniate  of  sodium)  are  quantitatively  analyzed  by  standard 
solution  of  nitrate  of  silver.  The  reactions  on  which  the  success  of 
the  process  depends  are  expressed  in  the  following  equations : — 

f AgNO^-f  2Na0y=NaCyAgCy+NaN03, 

I NaCyAgCy-4-AgN03=2AgCy+NaN03; 

KBr+ AgN03=AgBr+KN03 ; 

Na,HAs0,+3AgN03=Ag3As0,4-2NaN03+HN03. 


Standard  Solution  of  Nitrate  of  Silver. 

(Nitrate  of  Silver,  AgN03  = 170.) 

Dissolve  17  grammes  of  crj^stals  of  pure  nitrate  of  silver 
in  1 litre  of  water.  100  c.  c.  of  this  solution  contain  of 
the  molecular  weight  in  grammes  of  nitrate  of  silver,  and 
will  decompose  an  equivalent  quantity  of  a salt  of  any 
acidulous  radical  yielding  silver  compounds  insoluble  in 
water. 

Grammes  C.  c.  of 
of  substance,  vol.  sol. 

Acid,  hydrocyanic,  diluted,  B.  P.  and  U.  S.  P.  27.00  = 100.0 
Potassium,  bromide  of,  B.  P.  and  U.  S.  P.  . 1.19  = 100.0 
Sodium,  arseniate  of  (dry) 62  = 100.0 


VOLUMETRIC  ESTIMATION  OF  ACIDS.  487 


Diluted  hydrocijanic  acid  is  converted  into  cyanide  of 
sodium  by  adding  caustic  soda  until,  after  stirring,  litmus 
shows  that  the  liquid  has  an  alkaline  reaction.  The  nitrate- 
of-silver  solution  is  then  allowed  to  flow  in  gradually,  until, 
after  thorough  agitation,  a slight  permanent  turbidity  re- 
mains. When  this  occurs,  the  quantity  of  nitrate  of  silver 
added  represents  exactly  half  the  amount  of  real  hydrocy- 
anic acid  present  in  the  diluted  preparation.  Thus  the  100 
c.  c.  of  standard  solution  contains  molecular 

weight,  in  grammes,  of  nitrate  of  silver  (=  1.7)  ; this  would 
ordinarilj^  correspond,  in  a case  of  complete  decomposition, 
to  of  the  molecular  weight  in  grammes  of  hydrocyanic 
acid  (=  .27) ; 27  grammes  of  the  diluted  acid,  the  quantity 
employed  in  the  experiment,  apparently  contain  therefore 
.27  grammes  of  real  acid,  equal  to  1 per  cent.  A glance  at 
the  equation  shows  that  at  the  moment  cyanide  of  silver 
begins  to  be  precipitated,  only  half  of  the  cyanogen  has 
been  converted  into  cyanide  of  silver  ; the  quantity  of  acid 
indicated  by  the  amount  of  nitrate  added  must  therefore 
be  doubled  for  the  correct  percentage  (=  2). 

2HNC  eq.  to  AgNOg 
54  170 

Bromide  of  potassium  is  dissolved  in  distilled  water  in  a 
beaker,  and  the  standard  solution  added  until,  after  agita- 
tion of  the  liquid  and  subsidence  of  the  bromide  of  silver, 
a drop  of  the  solution  of  nitrate  of  silver  gives  no  more 
precipitate. 

KBr  + AgNOg 
119  170 

Arseniate  of  sodium  (Na2HAsO^,7H^O)  must  be  dried  at 
300°  F.  before  weighing.  It  is  thus  reduced  to  a definite 
anhydrous  salt  (Na2HAsOj,  losing,  if  pure,  40.38  per  cent, 
of  water.  Of  the  weighed  residue  .62  gramme  is  dissolved 
in  distilled  water,  3.3  c.  c.  of  the  vol.  sol.  of  soda  added,  and 
the  whole  treated  as  described  in  the  previous  paragraph. 

Na2HAs0,-fNaH0-f3AgN03=Ag3As0,  + 3NaN03  4-H.p 


Spirit  of  Wine  {Spiritus  Rectificatus,  B.  P.)  may  contain  traces 
of  ainylic  alcohol  and  aldehyd ; these  may  be  detected  by  nitrate  of 
silver,  which  is  reduced  by  them  to  the  metallic  state.  Any  quantity 
beyond  a mere  trace  of  such  bodies  renders  spirit  of  wine  too  impure 


488 


QUANTITATIVE  ANALYSIS. 


for  use  in  medicine.  ‘‘  Four  fluidounces  with  thirty  grain-measures 
(about  two  cub.  cent.)  of  the  volumetric  solution  of  nitrate  of  silver 
exposed  for  twenty-four  hours  to  bright  light,  and  then  decanted 
from  the  black  powder  which  has  formed,  undergoes  no  further 
change  when  again  exposed  to  light  with  more  of  the  test.” 


QUESTIONS  AND  EXERCISES. 

1001.  Explain  the  volumetric  method  of  estimating  the  strength 
of  aqueous  solutions  of  hydrocyanic  acid. 

1002.  How  much  nitrate  of  silver  will  indicate,  by  the  official 
volumetric  process,  the  presence  of  I part  of  real  hydrocyanic  acid  ? 
— Ans.  3.148  parts. 


ESTIMATION  OE  SUBSTANCES  READILY  OXIDIZED. 

Any  deoxidizer,  that  is,  any  substance  which  quickly  absorbs  a 
definite  amount  of  oxygen  or  is  susceptible  of  any  equivalent  action, 
may  be  quantitatively  tested  by  ascertaining  how  much  of  an  oxi- 
dizing agent  of  known  power  must  be  added  to  a given  quantity  ; 
before  complete  oxidation  is  effected.  The  oxidizing  agents  employed 
for  this  purpose  in  the  British  Pharmacopoeia  are  iodine  and  the 
red  chromate  of  potassium  ; permanganate  of  potassium  is  often  used 
for  the  same  purpose.  Iodine  acts  indirectly,  by  taking  hydrogen 
from  water  and  liberating  oxygen ; the  red  chromate  of  potassium  i 
directly,  by  the  facility  with  which  it  yields  three-sevenths  of  its  oxy-  i 
gen — as  indicated  by  the  equations  and  statements  given  on  page  j 
491 ; permanganate  of  potassium  by  affording  five-eighths  of  its  I 
oxygen  in  presence  of  acid,  2K^Mn^08  + GH^SO^  = 2K2SO4  -h 
4MnS04  + 6H20+502. 

Standard  Solution  of  Iodine. 

(Iodine,  I = I2Y.) 

Prepare  pure  iodine  by  mixing  the  commercial  article  ; 
with  about  a fourth  of  its  weight  of  iodide  of  potassium 
and  subliming.  Sublimation  may  be  effected  by  gently 
warming  the  mixture  in  a beaker,  the  mouth  of  which  is 
closed  by  a funnel ; the  iodine  vapor  condenses  on  the 
funnel;  wdiile  fixed  impurities  are  left  behind,  and  any 
chlorine  which  the  iodine  may  contain  is  absorbed  by  the  ( 
iodide  of  potassium,  an  equivalent  quantity  of  iodine  being  | 
liberated.  Small  quantities  may  be  similarly  treated  be- 
t^veen  two  watch-glasses,  placed  edge  to  edge.  Any  trace 
of  moisture  in  the  resublimed  iodine  is  removed  b}^  ex-  I 


VOLUMETRIC  ESTIMATION  OF  DEOXIDIZERS.  489 


posure  for  a few  hours  under  a glass  shade  near  a vessel 
containing  oil  of  vitriol. 

Place  12.Y  grammes  of  pure  iodine  and  about  18  grammes 
of  pure  iodide  of  potassium  (an  aqueous  solution  of  which 
is  the  best  solvent  of  iodine ; the  salt  plays  no  other  part 
in  these  operations)  in  a litre  flask,  add  a small  quantity 
of  water,  and  agitate  until  the  iodine  is  dissolved,  dilute 
to  1 litre.  100  c.  c.  of  this  solution  contain  of  the 
molecular  weight  of  free  iodine  in  grammes,  and,  water  being 
present,  will  cause  the  oxidation  of  of  the  molecular 
weight  of  sulphurous  acid  (H2SO3)  in  grammes  ( = .41),  or 
(=.32)  of  sulphurous  acid  gas  (SO2),  sulphuric  acid 
being  formed.  100  c.  c.  will  also  oxidize  of  the  molec- 
ular weight  of  arsenious  acid  (HgAsOg)  in  grammes,  or 
of  the  molecular  weight  of  common  white  arsenic 
(AS2O3)  in  grammes  (=.495),  arsenic  acid  (HgAsOJ  being 
produced.  The  reactions  are  expressed  in  the  following 
equations: — 

I2+  + 

+ S02::=.2HI+H^S0,. 

1^4.  H2O  + H3As03= 2HI  + H^AsO,. 

2X3-4-  5H2O  + As203=4HI  4-  SHgAsO^. 
l2H-2(Na2S2O3,5H2O)=2NaI-fNa2S,Og-fl0H^O. 

The  following  official  substances  are  tested  with  the 


standard  solution  of  iodine : — 

Grammes  of 

C c.  of 

sabstance. 

vol.  sol. 

Acid,  solution  of  sulphurous  . . . 

3.47 

= 100 

Arsenic,  in  mass,  B.  P.  and  U.  S.  P.  . 

. 0.495 

= 100 

‘‘  in  alkaline  sol.  {Liq.  Arsenicalis)  54.64 

==  100 

‘‘  in  acid  sol.  {Liq,  Arsen.  Hydrochl.)  54.64 

= 100 

Sodium,  hyposulphite  of 

. 2.48 

= 100 

The  solution  of  sulphurous  acid  is  diluted  with  three- 
fourths  of  a litre  of  cold  water,  and  the  iodine  solution 
added  until  a slight  permanent  brown  tint  is  produced, 
showing  the  presence  of  free  iodine.  A better  indication 
of  the  termination  of  the  action  is  afforded  by  mucilage 
of  starch,  which  gives  a blue  color  with  the  slightest  trace 
of  iodine.  As  already  stated,  100  c.  c.  of  this  volumetric 
solution  contain  an  amount  of  free  iodine  sufficient  to 
cause  the  oxidation  of  2^^  of  the  molecular  weight  of 
either  sulphurous  acid  or  sulphurous  acid  gas.  Now  2^0 
of  the  molecular  weight  of  sulphurous  acid  (II3SO3)  in 
grammes  is  0.41 ; if  3.4T  grammes  of  the  solution  contain 


490 


QUANTITATIVE  ANALYSIS. 


0.41  of  the  acid,  100  of  the  solution  will  be  found  to  con- 
tain 11.8.  By  a similar  calculation  the  official  solution 
may  be  shown  to  contain,  or,  rather,  yield  9.22  per  cent,  of 
sulphurous  acid  gas  (SO^). 

If  the  sulphurous  acid  be  diluted  to  a less  degree  than 
.04  or  .05  per  cent.,  there  will  be  some  risk  of  the  sulphuric 
acid  formed  being  again  reduced  to  sulphurous  acid,  with 
liberation  of  iodine.  In  delicate  experiments  the  distilled 
water  used  for  dilution  should  previously  be  freed  from  air 
by  boiling,  to  prevent  the  small  amount  of  oxidizing  action 
which  dissolved  air  would  exert. 


H2SO3  eq.  to  I2 
82  254 


SO2  eq.  to  I2 
64  254 


The  solid  arsenic  is  dissolved  in  boiling  water  by  help 
of  about  two  grammes  of  bicarbonate  of  sodium.  When 
the  liquid  is  quite  cold,  mucilage  of  starch  is  added,  and 
the  iodine  solution  allowed  to  flow  in  until,  after  well  stir- 
ring, a permanent  blue  color  is  produced. 


II^AsOg  eq.  to  I3 
126  254 


As,03  eq.  to  21^ 
198  508 


The  arsenical  solution  already  containing  some  carbonate 
of  potassium  requires  only  about  one  and  a half  gramme 
of  bicarbonate  of  sodium  for  neutralization  of  the  arsenious 
acid.  After  boiling  and  cooling,  starch  and  the  iodine 
solution  are  added  as  before. 

The  solution  of  arsenic  in  dilute  hydrochloric  acid 
requires  about  three  grammes  of  acid  carbonate  of  sodium, 
if  54  or  55  grammes  of  solution  is  the  quantity  employed. 
After  boiling  for  a few  minutes  and  cooling,  the  starch  and 
iodine  are  added. 

These  arsenical  solutions  contain  .9  per  cent,  of  arsenic. 

The  Hyposulphate  of  sodium  is  dissolved  in  water,  starch 
mucilage  added,  and  the  iodine  solution  slowly  run  in,  the 
whole  being  frequently  stirred,  until  a permanent  blue 
color  is  produced. 

In  the  previous  reactions  iodine  has  acted  as  an  indirect 
oxidizing  agent  by  uniting  with  the  hydrogen  and  thus 
liberating  the  oxygen  of  water.  In  the  present  case  it 
unites  with  an  analogue  of  hydrogen,  namely,  sodium. 


VOLUMETRIC  ESTIMATION  OF  DEOXIDIZERS.  491 


QUESTIONS  AND  EXERCISES. 

1003.  Give  equations  illustrative  of  the  reactions  on  which  the  use 
of  a standard  volumetric  solution  of  iodine  is  based. 

1004.  From  what  point  of  view  may  iodine  be  regarded  as  an  oxi- 
dizing agent  ? 

1005.  What  reagent  indicates  the  termination  of  the  reaction  be- 
tween deoxidizing  substances  and  moist  iodine  ? 

1006.  How  much  sulphurous  acid  gas  will  cause  the  absorption  of 
2.54  parts  of  iodine  in  the  volumetric  reaction  ? Ans.  .64. 

1007.  What  quantity  of  iodine  will  be  required,  under  appropriate 
conditions,  to  oxidize  5 parts  of  arsenic?  Ans.  12.828. 

1008.  Find  by  calculation  the  amount  of  hyposulphite  of  sodium 
equivalent  to  13  parts  of  iodine  in  volumetric  analysis.  Ans.  25.389. 


Standard  Solution  of  Red  Chromate  of  Potassium. 

(Red  Chromate  of  Potassium,  K^CrO^,  CrO^  = 295.) 

One  molecule  of  red  chromate  of  potassium  in  presence  of  an  acid, 
under  favorable  circumstances,  yields  four  atoms  of  oxygen  to  the 
hydrogen  of  the  acid,  leaving  three  available  either  for  direct  oxida- 
tion or  for  combination  with  the  hydrogen  of  more  acid,  an  equiva- 
lent proportion  of  acidulous  radical  being  liberated  for  any  required 
purpose. 

When  used  as  a volumetric  agent,  the  red  chromate  always  yields 
the  whole  of  its  oxygen  to  the  hydrogen  of  the  accompanying  acid, 
a corresponding  quantity  of  acidulous  radical  being  set  free — four- 
sevenths  of  this  radical  immediately  combining  with  the  potassium 
and  chromium  of  the  red  chromate,  three-sevenths  becoming  avail- 
able. Ferrous  may  thus  be  converted  inta  ferric  salts  with  sufficient 
rapidity  and  exactitude  to  admit  of  the  estimation  of  an  unknown 
quantity  of  iron  by  a known  quantity  of  the  red  chromate.  As  one 
atom  of  the  liberated  acidulous  radical  will  convert  two  molecules  of 
ferrous  into  one  of  ferric  salt,  one  molecule  of  red  chromate  causes 
six  of  ferrous  to  become  three  of  ferric,  as  shown  in  either  of  the  fol- 
lowing equations : — 

K^CrO,,  Cr03+7H2S0,+  6FeS0,=K2S0,, 

+3(Fe,3SO,); 

K.CrO^,  Cr03+14HC14-  6FeCl2=2KCH-0r2Cl6+7H,O+3Fe,0l6. 

These  equations  indicate  that,  in  presence  of  excess  of  acid,  295 
parts  (the  molecular  weight)  of  red  chromate  of  potassium  will  con- 
vert 1668  parts  of  crystallized  ferrous  sulphate,  6(FeS04,7H20= 
278),  or  an  equivalent  quantity  of  ferrous  chloride  (6FeOl2=762), 
ferrous  carbonate  (6FeC03=696),  ferrous  arseniate  (2Fe3As20g= 
892),  ferrous  phosphate  (2Fe3P208=716),  or  iron  itself  (3Fe2=336), 
into  ferric  salt.  If  these  parts  be  taken  in  grammes,  ^ J ^ or  less  of 
the  stated  amounts  will  be  found  to  be  convenient  quantities  for 
experiment. 


492 


QUANTITATIVE  ANALYSIS. 


Dissolve  1 4. Y 5 grammes  of  red  chromate  of  potassium  in 
one  litre  of  distilled  water.  100  c.  c.  of  this  solution  con- 
tain 2^77  of  the  molecular  weight  of  the  salt  in  grammes, 
and  will  cause  the  conversion  of  of  the  weight  of  6 
atoms  of  iron  in  grammes,  or  an  equivalent  quantity  of 
the  lower  salts  of  iron,  from  the  ferrous  to  the  ferric  state. 
The  solution  is  used  in  determining  the  strength  of  the 
following  official  ferrous  preparations.  It  is  known  that 
the  whole  of  the  ferrous  has  been  converted  to  ferric  salt 
when  a small  drop  of  the  liquid- placed  in  contact  with  a 
drop  of  a very  dilute  solution  of  ferridcyanide  of  potas- 
sium, on  a white  plate,  ceases  to  strike  a blue  color. 


Grammes  of 

C.  c.  of 

substance. 

v*ol.  sol. 

Iron, 

, arseniate  of 

. . 2.94  - 

25 

u 

magnetic  oxide  of  ...  . 

. . 2.41  = 

10 

phosphate  of,  B.  P.  and  U.  ^ 

:;.P  . 2.00  = 

25 

u 

saccharated  carbonate  of  . 

. . 4.70  = 

50 

The  several  compounds  are  dissolved  in  excess  of  hydro- 
chloric acid  diluted  with  water,  and  the  standard  solution 
then  dropped  in.  The  ferrous  liquid  must  not  be  exposed 
to  the  air  for  more  than  a few  seconds  after  solution  has 
been  effected,  or  oxygen  will  be  absorbed  and  a corres- 
ponding amount  of  ferric  salt  formed  before  the  volumetric 
oxidizing  agent  is  added:  in  most  cases  diluted  sulphuric 
acid  may  be  used  as  a solvent  of  the  ferrous  salt,  ferrous 
sulphate  absorbing  oxygen  from  the  air  far  less  rapidly 
than  ferrous  chloride.  It  will  be  found  that  the  propor- 
tion of  carbonate  of  iron  in  the  saccharated  compound,  as 
indicated  by  the  above  numbers,  is,  3Y  in  100.  Trade 
samples  yield  from  20  to  30,  and  sometimes  35  per  cent., 
according  to  the  care  with  which  oxidation  has  been  pre- 
vented. The  theoretical  percentage  obtainable  from  the 
ingredients  is  45.5,  the  quantit}^  that  would  be  present  if 
the  compound  were  anhydrous  and  unox3"dized,  conditions 
never  obtained  in  practice.  The  2 grammes  of  phosphate 
of  iron  should  contain  .895  of  real  ferrous  phosphate  or 
nearly  45  per  cent. 

The  use  of  these  two  volumetric  solutions  in  quantita- 
tive analj'sis  admits  of  great  extension. 


VOLUMETRIC  ESTIMATION  OF  OXIDIZERS.  493 


QUESTIONS  AND  EXERCISES. 

1009.  Write  equations  explanatory  of  the  oxidizing  power  of  red 
chromate  of  potassium. 

1010.  One  hundred  cubic  centimetres  of  an  aqueous  solution  of  red 
chromate  of  potassium  contain  of  the  molecular  weight  of  the 
salt  in  grammes ; what  weight  of  metallic  iron,  dissolved  in  hydro- 
chloric acid,  will  this  volume  oxidize  ? — Ans.  1.68  gramme. 

1011.  If  8.34  grammes  of  a specimen  of  crystallized  ferrous  sul- 
phate require  93  c.  c.  of  the  standard  solution  of  chromate  for  com- 
plete oxidation,  what  percentage  of  real  salt  is  present  ? — Ans.  93. 

1012.  How  much  red  chromate  of  potassium  is  required  for  the 
conversion  of  10  parts  of  ferrous  sulphate  into  ferric  salt? — Ans. 
1.768. 

1013.  What  quantity  of  pure  ferrous  carbonate  is  indicated  by 
1.475  part  of  red  chromate  as  applied  in  volumetric  analysis  ? — Ans. 
3.48. 

1014.  State  the  amount  of  official  saccharated  carbonate  of  iron 
equivalent  to  .7375  part  of  red  chromate  in  the  volumetric  reaction. 
— Alts.  4.7. 


ESTIMATION  OF  SUBSTANCES  READILY  DEOXIDIZED. 

Any  substance  which  quickly  yields  a definite  amount  of  oxygen 
may  be  quantitatively  tested  by  ascertaining  how  much  of  a deoxi- 
dizing agent  of  known  power  must  be  added  to  a given  quantity  be- 
fore complete  deoxidation  is  effected.  The  chief  compounds  which 
may  be  used  as  absorbers  of  oxygen  (deoxidizers  oi*  reducing  agents, 
as  they  are  commonly  termed)  are  hyposulphite.of  sodium,  sulphurous 
acid,  ferrous  sulphate,*  oxalic  acid,  arsenious  acid.  The  first-named 
is  officially  employed  ; it  is  only  used  in  the  estimation  of  free  iodine, 
and,  indirectly,  of  chlorine  and  chlorinated  compounds.  Iodine  and 
chlorine  are  regarded  as  oxidizing  agents,  because  their  great  affinity 
for  hydrogen  enables  them  to  become  powerful  indirect  oxidizers  in 
presence  of  water. 

Standard  Solution  of  Hyposulphite  of  Sodium. 
(Crystallized  Hyposulpliiteof  Sodium, Na2S203,5H20  = 248.) 

Dissolve  about  30  grammes  of  h^^posulpliite  of  sodium 
in  a litre  or  less  of  water.  Fill  a burette  with  this  solu- 
tion, and  allow  it  to  flow  into  a beaker  containing  exactly 
100  c.  c.  of  the  volumetric  solution  of  iodine  until  the 
brown  color  of  the  iodine  is  just  discharged — or,  starch 

* “Five  grains  of  Permanganate  of  Potassium  dissolved  in  water 
require  for  decoloration  a solution  of  forty-four  grains  of  granulated 
sulphate  of  iron  acidulated  with  two  fluidrachms  of  diluted  sulphuric 
acid.” — B.  P. 

42 


494 


QUANTITATIVE  ANALYSIS. 


being  added,  until  the  blue  iodide  of  starch  is  decolorized. 
Note  the  number  of  c.  c.  of  hyposulphite  solution  required, 
and  to  the  bulk  of  the  solution  add  water,  so  that  2.48 
grammes  of  hyposulphite  of  sodium  shall  be  contained  in 
every  100  c.  c. 

When  iodine  and  hyposulphite  of  sodium  react,  two  atoms  of 
iodine  remove  two  of  sodium  from  two  molecules  of  the  hyposulphite, 
tetrathionate  of  sodium  being  formed,  as  indicated  in  the  following 
equation : — 

1,  4-  2Na2S,03  = 2NaI  + Na.S.Og. 

As,  therefore,  100  c.  c.  of  the  iodine  solution  contain  of  the 
atomic  weight  of  iodine  in  grammes,  100  c.  c.  of  the  standard  solution 
of  hyposulphite  of  sodium  will  contain  yiiy  of  the  molecular  weight 
of  the  salt  in  grammes,  and  will  show  the  existence  of  of  the 
atomic  weight  of  iodine  in  grammes  in  any  quantity  of  a liquid  nor- 
mally containing  free  iodine,  or  iodine  liberated  by  an  equivalent 
quantity  of  free  chlorine. 


This  solution  is  employed  for  quantitatively  testing  the 
following  substances : — 


Chlorine,  solution  of  ...  . 

Grammes  of 
substance. 

. . 29.26  = 

C.  c.  of 
vol.  sol. 

50 

Iodine,  B.  P.  and  U.  S.  P.  . . 

. . 1.27  = 

100 

Lime,  chlorinated 

. . 1.17  - 

100 

solution  of  chlorinated  . 

. . 6.00  = 

50 

Soda,  solution  of  chlorinated  ,. 

. . 7.00  = 

50 

2^ote. — Owing  to  the  volatility  of  chlorine  and  iodine, 
and  the  readiness  with  w^hich  they  attack  the  metals  of 
which  balances  are  made,  it  is  not  desirable  to  experiment 
on  stated  weights  of  substances  containing  these  elements. 
A small  stoppered  bottle  or  tube  containing  the  material 
may  be  counterpoised,  and  a convenient  quantity  removed 
for  analysis,  the  precise  amount  taken  being  ascertained 
by  again  weighing  the  bottle. 

The  iodine  may  be  dissolved  in  water  containing  about 
a gramme  and  a half  of  iodide  of  potassium,  a salt  giving 
no  reaction  with  hyposulphite  of  sodium. 

I2  eq.  to  2(Na2S203,6H20) 

254  496 

It  is  assumed  in  this  operation  that  the  iodine  has  been  | 
shown  by  qualitative  analysis  to  be  free  from  chlorine  and  | 
bromine.  These  elements  resemble  iodine  in  reacting  with  I 


VOLUMETRIC  ESTIMATION  OF  OXIDIZERS.  495 


hyposulphite  of  sodium,  hence  would  reckon  as  iodine  in  a 
volumetric  assay. 

The  solution  of  chlorine  is  added  to  water  containing  ex- 
cess of  iodide  of  potassium  (about  a gramme  and  a third); 
a quantity  of  iodine,  equivalent  to  the  amount  of  chlorine 
present,  is  thus  liberated.  The  hyposulphite  solution  is 
then  dropped  in. 

Cl,  eq.  to  2(Na,S,03, 5H,0) 

' — ' V ' 

n 496 

The  chlorinated  lime  (“chloride  of  lime”  or  “bleaching- 
pow^der”)  is  mixed  with  about  a fifth  of  a litre  of  water 
containing  excess  of  iodide  of  potassium  (3.5  grms.)  and 
acidulated  with  hydrochloric  acid.  The  available  oxygen 
of  the  chlorinated  lime  liberates  chlorine  from  an  equivalent 
quantity  of  hydrochloric  acid  ; and  this,  with  the  available 
chlorine  of  the  chlorinated  lime,  sets  free  an  equivalent 
amount  of  iodine  from  the  iodide  of  potassium.  The  hypo- 
sulphite and  iodine  reacting  show  the  direct  and  indirect 
oxidizing  power  of  the  chlorinated  lime;  it  should  corre- 
spond to  30  per  cent,  of  chlorine.  For  example,  as  248  (1 
molecule)  of  hyposulphite  indicate  the  presence  of  35.5  (1 
atom)  of  chlorine,  2.48  of  h3q30sulphite  (the  quantity  in  100 
c.  c.)  indicate  the  presence  of  .355  of  chlorine.  If  100  c.  c. 
have  been  used,  therefore,  .355  of  chlorine  is  obtainable 
from  the  quantity  of  bleaching-powder  employed  (1.1  T). 
And  if  1.1 'Z  of  bleaching-powder  yield  .355  of  chlorine,  100 
will  yield  about  30  (30|-  nearly). 

The  solution  of  chlorinated  lime  is  mixed  with  about  a 
fifth  of  a litre  of  water  containing  a couple  of  grammes  of 
iodide  of  potassium,  and  ten  or  twelve  c.  c.  of  hydrochloric 
acid.  The  hyposulphite  solution  is  then  added  from  a 
burette  until  the  color  of  the  liberated  iodine  is  just  dis- 
charged. The  solution  of  chlorinated  soda  is  similarly 
treated. 

Note. — 1.  In  these  experiments  the  blue  color  formed  on 
the  addition  of  mucilage  of  starch  to  the  liquids  will  be 
found  to  be  a more  delicate  indicator  of  the  termination  of 
i reactions  than  the  brown  tint  of  the  iodine. 

Note. — 2.  Standard  solutions  used  in  volumetric  analysis  are  often 
described  as  normal,  decinormal,  and  centinormal.  A normal  solu- 
tion (N)  contains  in  every  litre  the  molecular  weight  of  the  salt, 
talcenin  grammes;  a decinormal  solution  is  one-tenth  (/j),  and  a 
I centinormal  (1^5)  one-hundredth  the  strength  of  such  a normal  solu- 
' tion. 


496 


QUANTITATIVE  ANALYSIS. 


QUESTIONS  AND  EXERCISES. 

1015.  For  what  purposes  is  the  official  volumetric  solution  of  hypo- 
sulphite of  sodium  used  ? 

1016.  On  what  reaction  is  based  the  quantitative  employment  of 
hyposulphite  of  sodium? 

1017.  How  much  hyposulphite  of  sodium  is  required  to  show  the 
presence  of  10  parts  of  iodine  ? — Ans.  19.527. 

1018.  To  what  amount  of  chlorine  is  4.96  parts  of  hyposulphite  of 
sodium  equivalent  in  volumetric  analysis? — Ans.  0.71. 

1019.  Describe  the  operations  included  in  the  estimation  of  the 
strength  of  bleaching-powder. 

1020.  By  what  reagent  is  the  complete  absorption  of  free  iodine 
by  hyposulphite  of  sodium  indicated? 


MISCELLANEOUS  PROBLEMS. 

1021.  How  much  bicarbonate  of  potassium  is  contained  in  an 
eight-ounce  bottle  of  medicine,  seven  fluidrachms  of  which  are  satu- 
rated by  two  and  a half  grains  of  crystallized  oxalic  acid  ? — Ans. 
18.1  grains. 

1022.  A sample  of  soda-ash  is  said  to  contain  78  per  cent,  of  pure 
anhydrous  carbonate  of  sodium  ; if  the  statement  is  true,  how  much 
of  the  official  volumetric  solution  of  oxalic  acid  will  saturate  5 
grammes  of  the  specimen  ? — Ans.  73.6. 

1023.  2.69  grammes  of  common  brown  sulphuric  acid  are  saturated 
by  43.5  cubic  centimetres  of  the  official  volumetric  solution  of  soda  ; 
how  much  acid  of  96.8  per  cent,  is  present? — Ans.  The  2.69  con- 
tain 2.2. 

1024.  Four  grammes  of  a litre  and  a half  of  concentrated  hydro- 
cyanic acid  are  neutralized  by  89  cubic  centimetres  of  volumetric 
solution  of  nitrate  of  silver  of  official  strength  ; to  what  volume  must 
the  bulk  of  the  acid  be  diluted  for  the  production  of  acid  of  pharma- 
copoeia! strength  ? — Ans.  9 litres. 

1025.  3.18  grammes  of  a pow’der  containing  arsenic  require  for 
complete  reaction  84  cubic  centimetres  of  a volumetric  solution  of 
iodine,  which  is  1.43  weaker  than  the  standard  solution  of  the  British 
Pharmacopoeia  ; what  percentage  of  pure  arsenic  is  contained  in  the 
pow'der  ? — Ans.  12.86. 

1026.  Ho\v  much  pure  metal  is  present  in  a sample  of  iron  1.68 
gramme  of  which  dissolved  in  dilute  sulphuric  acid,  is  exactly 
attacked  by  95.7  cubic  centimetres  of  a semi-decinornial  volumetric 
solution  of  red  chromate  of  potassium  which  is  6 per  cent,  too 
strong  ? 


GRAVIMETRIC  ESTIMATION  OF  POTASSIUM,  497 


GRAVIMETRIC  ANALYSIS. 

ESTIMATION  OF  METALS. 

POTASSIUM. 

Outline  of  the  Process. — This  element  is  usually  estimated  in  the 
form  of  double  chloride  of  potassium  and  platinum.  Qualitative 
analysis  having  proved  the  presence  of  potassium  and  other  ele- 
ments in  a substance,  a small  quantity  of  the  material  is  accurately 
weighed,  dissolved,  and  the  other  elements  removed  by  appropriate 
reagents  ; the  precipitates  are  well  washed,  in  order  that  no  trace  of 
the  potassium  salt  shall  be  lost,  the  resulting  liquid  concentrated 
over  a water-bath  (to  avoid  loss  that  would  occur  mechanically 
during  ebullition),  hydrochloric  acid  added  if  necessary,  solution  of 
perchloride  of  platinum  poured  in,  and  evaporation  continued  to 
dryness  ; excess  of  the  perchloride  is  then  dissolved  by  adding  spirit 
of  wine  containing  half  its  bulk  of  ether  (a  liquid  in  which  the  double 
chloride  is  insoluble),  the  mixture  carefully  poured  on  to  a tared 
and  dried  filter,  washed  with  the  spirit  till  every  trace  of  free  per- 
chloride of  platinum  is  removed,  the  whole  dried  and  weighed  ; from 
the  resulting  amount  the  proportion  of  potassium,  or  equivalent 
quantity  of  a salt  of  potassium,  is  ascertained  by  calculation. 

Note. — From  this  short  description  it  will  be  seen,  first,  that 
the  chemistry  of  quantitative  is  the  same  as  that  of  qualitative 
analysis ; the  second,  that  the  principle  of  gravimetric  is  the 
same  as  that  of  volumetric  quantitative  analysis — the  combining- 
proportions  being  known,  unknown  quantities  of  elements  may 
be  ascertained  by  calculation  from  known  quantities  of  their 
compounds. 

Apjpo^ratus. — In  addition  to  a delicate  balance  and 
weights  and  the  common  utensils,  a few  special  instru- 
ments are  used  in  quantitative  manipulation ; some  of 
these  may  be  prepared  before  proceeding  with  the  estima- 
tion of  potassium. 

Filtering-paper  may  be  of  the  kind  known  as  ‘‘  Swedish,’^ 
the  texture  of  which  is  of  the  requisite  degree  of  closeness, 
and  its  ash  small  in  amount.  A large  number  of  circular 
pieces  of  one  size,  six  to  eight  centimetres  in  diameter, 
should  be  cut  ready  for  use.  In  delicate  experiments, 
where  a precipitate  on  a filter  has  to  be  heated  and  the 
paper  consequently  burnt,  the  weight  of  the  ash  of  the 
filter  must  be  deducted  from  the  weight  of  the  residue. 
The  ash  is  estimated  by  burning  ten  or  twenty  of  the  cut 
filters.  These  are  folded  into  a small  compass,  a portion 

42* 


498 


QUANTITATIVE  ANALYSIS. 


of  a piece  of  platinum  wire  twisted  a few  times  round  the 
packet,  so  as  to  form  a cage,  the  whole  held  by  the  free 
end  of  the  wire  over  a w eighed  porcelain  crucible  placed  in 
the  centre  of  a sheet  of  glazed  paper,  the  bundle  ignited  by 
a spirit-lamp  or  smokeless  gas-flame,  the  flame  allowed 
to  impinge  against  the  charged  mass  till  it  falls  into  the 
crucible  below,  any  stray  fragments  on  the  sheet  carefully 
shaken  into  the  crucible,  the  latter  placed  over  a flame  till 
carbon  has  all  burnt  off  and  nothing  but  ash  remains,  the 
whole  cooled,  weighed,  and  the  weight  of  the  crucible  de- 
ducted; the  weight  of  the  residue  divided  by  the  number  of 
pieces  used  gives  the  average  amount  of  ash  in  each  filter. 

A pair  of  Weighing-tubes^  for  holding  dried  filters  during 
operations  at  the  balance,ma3"  be  made  from  two  test-tubes, 
one  fitting  closely'  within  the  other.  About  five  centimetres 
of  the  closed  end  of  the  outer  and  seven  of  the  inner  are 
cut  off,  hy  leading  a crack  round  the  tube  with  a pencil  of 
incandescent  charcoal,  and  the  sharp  edges  fused  in  the 
blowpipe-flame.  A filter,  after  drying,  is  quicklj^  folded 
and  placed  in  the  narrower  tube,  the  mouth  of  which  is  then 
closed  by  the  wider  tube.  This  prevents  reabsorption  of 
moisture  from  the  air. 

The  Washing-bottle  the  spirit  of  wine  and  ether  ^ 

is  a common  bottle,  through  the  cork  of  which  a short 
straight  tube  passes.  The  outer  end  of  the  tube  should  be 
sufficiently  narrowed  to  enable  it  to  deliver  a ver}"  fine 
stream  of  the  liquid.  The  bottle  being  inverted,  the  w^armth 
of  the  hand  expands  the  air  and  vapor  to  a sufficient  ex- 
tent to  force  out  the  liquid. 

The  Ordinary  Washing-bottle  for  quantitative  operations 
should  be  formed  of  a flask  in  which  water  may  be  boiled, 
fitted  up  as  usual  {vide  p.  93). 

A Water-oven  is  the  best  form  of  drying-apparatus.  It  is  a small 
square  copper  vessel,  jacketed  on  five  sides  and  having  a door  on  the 
sixth ; water  is  poured  into  the  space  between  the  inner  and  outer 
casing,  and  the  whole  placed  over  a gas-lamp  or  source  of  heat, 
moist  air  and  steam  escaping  by  appropriate  apertures.  Desiccation 
at  higher  temperatures  than  the  boiling-point  of  water  may  be  prac- 
tised by  using  oil  or  paraffin  instead  of  water,  inserting  a thermome- 
ter in  the  fat.  The  apparatus  may  be  purchased  of  any  maker  of 
chemical  instruments. 

Pure  distilled  water  must  be  used  in  all  quantitative  determina- 
tions. 

Note. — In  practising  the  operations  of  quantitative  analysis, 
experiments  should  at  first  be  conducted  on  definite  salts  of 
known  composition,  for  the  accuracy  of  results  may  then  be  tested 
by  calculation. 


GRAVIMETRIC  ESTIMATION  OF  POTASSIUM.  499 


Estimation  of  Potassium  in  the  form  of  double  chloride 
of  potassium  and  platimim, — Select  two  or  three  crystals  of 
pure  nitrate  of  potassium,  powder  them  in  a clean  mortar, 
dry  the  powder  by  gently  heating  in  a porcelain  crucible 
over  a flame  for  a few  seconds,  place  about  a couple  of 
decigrammes  (0.2  grm.)  of  the  powder  in  a counterpoised 
watch-glass,  accurately  weigh  the  selected  quantity,  trans- 
fer to  a small  dish,  letting  water  from  a wash-bottle  flow 
over  the  watch-glass  and  run  into  the  dish,  warm  the  dish 
till  the  nitrate  is  dissolved,  acidulate  with  hydrochloric 
acid,  add  excess  of  .aqueous  solution  of  perchloride  of  pla- 
tinum (a  quantity  containing  about  0.4  of  solid  salt), 
evaporate  to  dryness  over  a water-bath.  While  evapora- 
tion is  going  on,  place  a filter  and  the  weighing-tubes  in  the 
water-oven,  exposing  them  to  a temperature  of  212°  F.  for 
about  half  an  hour ; fold  the  filter  and  insert  it  in  the  tubes, 
place  them  on  a plate  under  a glass  shade,  and  when  cold 
accurately  note  their  weight.  Arrange  the  weighed  filter 
in  a funnel  over  a beaker.  Transfer  the  dried  and  cooled 
platinum  salt  from  the  dish  to  the  filter  by  moistening  the 
residue  with  the  mixture  of  alcohol  and  ether,  and,  when 
the  salt  is  loosened,  pouring  the  contents  of  the  dish  into 
the  paper  cone.  Any  salt  still  adhering  may  be  freed  by 
the  finger,  which,  together  with  the  dish,  should  be  washed 
in  the  stream  of  spirit,  the  rinsings  at  once  flowing  into 
the  filter.  The  filtrate  should  have  a yellowish-brown 
color,  due  to  the  excess  of  perchloride  of  platinum.  If 
it  is  colorless,  an  insufficient  amount  of  perchloride  has 
been  added,  and  the  whole  operation  must  be  repeated.  The 
washed  precipitate  and  filter  are  finally  dried  in  the  water- 
oven,  folded  and  placed  in  the  v^eighing-tubes,  the  drying 
continued  until  the  whole,  after  repeated  weighing  when 
cold,  ceases  to  alter;  the  final  weight  is  noted. 

Note. — If  filters  are  not  freed  from  all  trace  of  acid  by  thorough 
washing,  the  paper  will  be  brittle  when  dry,  falling  to  pieces  on 
being  folded. 

Analytical  memoranda  in  the  note  book  may  have  the 
following  form: — 

Watch-glass  and  substance  .... 

Watch-glass 

Substance  . . 

Weighing-tubes,  filter,  and  Pt  salt  . . 

Weighing-tubes  and  filter 

PtCI,,2KCl.  . . 


500 


QUANTITATIVE  ANALYSIS. 


The  calculations  are  simple: — 

|I  tW,^2KCl|  equivalent  to 

ithe  weight  of  ^ 

double  chloride  >•  is  equivalent  to  x.  x will  be  the 
obtained  ) 

amount  of  pure  nitrate  of  potassium  in  the  quantity  of  sub- 
stance operated  on.  x should,  in  the  present  instance,  be 
identical  with  the  weight  of  substance  taken,  because,  for 
educational  purposes,  pure  nitre  is  undei-examination.  Only 
after  analyses  of  pure  substances  have  yielded  the  operator 
results  identical  with  those  by  calculation,  can  analyses  of 
substances  of  unknown  degree  of  purity  be  undertaken 
with  confidence.  A table  of  atomic  weights,  from  which 
to  find  molecular  weights,  is  given  in  the  Appendix. 

A Water-bath  for  the  evaporation  of  liquids  or  for  drying  moist 
solids  at  temperatures  below  212^  F.  is  an  iron,  tin,  or  earthenware 
pan,  the  mouth  of  w^hich  can  be  narrowed  by  iron  or  tin  diaphragms 
of  various  sizes  and  having  orifices  adapted  to  the  diameters  of 
evaporating-dishes  or  plates.  In  the  British  Pharmacopoeia,  “ when 
a loater-bath  is  directed  to  be  used,  it  is  to  be  understood  that  this 
term  refers  to  an  apparatus  by  means  of  which  water  or  its  vapor,  at 
a temperature  not  exceeding  2120.  jg  applied  to  the  outer  surface  of 
a vessel  containing  the  substance  to  be  heated,  which  substance  may 
thus  be  subjected  to  a heat  near  to,  but  necessarily  below,  that  of 
2120.  In  the  steam-bath  the  vapor  of  water  at  a temperature  above 
2120,  i^at  not  exceeding  230O,  is  similarly  applied.” 

Evaporation  in  vacuo  is  performed  by  simply  placing  the  vessel 
of  liquid  over  or  by  the  side  of  a small  reservoir  of  strong  sulphuric 
acid  or  other  absorbent  of  moisture,  on  the  plate  of  an  air-pump, 
covering  with  a capacious  receiver,  and  exhausting. 

Platinum  residues  should  be  preserved,  and  the  metal  recovered 
from  them  from  time  to  time  [vide  p.  221). 

Hot  alcohol  sometimes  reduces  perchloride  of  platinum,  the  metal 
being  thrown  out  of  solution  in  a finely  divided  form,  known  plati- 
num black  ; only  aqueous  solutions,  therefore,  of  the  salt  should  be 
used  where  heat  is  employed.  Hence,  also,  in  washing  out  excess 
of  perchloride  of  platinum  from  the  double  chloride  of  platinum  and 
potassium  by  spirit,  the  application  of  heat  should  be  avoided. 

Effervescing  Potasli-ivater  [Liquor  Potassce  Effervescens,  B.P.) 
is  most  easily  estimated  volumetrically  (p.  481).  Any  adulteration 
by  an  equivalent  amount  of  bicarbonate  of  sodium  would,  however, 
by  that  process  be  undetected ; hence  the  Pharmacopoeia  directs 
that  “ five  fluidounces,  evaporated  to  one-fifth,  and  r2  grains  of  tar- 
taric acid  added,  yield  a crystalline  precipitate,  which,  when  dried, 
weighs  not  less  than  12  grains.”  Five  fluidounces  of  this  prepara- 
tion should  contain  7.5  grains  of  bicarbonate,  convertible  into  14.1 


GRAVIMETRIC  ESTIMATION  OP  SODIUM.  501 


grains  of  acid  tartrate  of  potassium  by  11.25  grains  of  tartaric  acid. 
The  method  is  somewhat  rough,  but  quite  efficient  for  “ potash-water” 
containing  nothing  but  bicarbonate  of  potassium. 


Proportional  weights  of  equivalent  quantities  of  potassium 
and  its  salts. 


Metal 

K, 

. 78 

Oxide  (“  potash’^)  . . . . 

K,0  .... 

. 94 

Hydrate  (“caustic  potash’’) 

2KHO  .... 

. 112 

Carbonate  (anhydrous)  . 

K^CO,.  . . . 

. 138 

Carbonate  (crystalline)  . . 

K,CO,+16%  aq. 

. 164.285 

Bicarbonate 

2KHC63  . . . 

. 200 

Nitrate 

2KNO3  .... 

. 202 

Platinum  salt 

PtCl,,  2KCI  . . 

. 489 

SODIUM. 

Sodium  is  usually  estimated  as  sulphate.  Accurately 
weigh  a porcelain  crucible  and  lid,  place  within  about  .3  of 
pure  rock-salt,  and  again  weigh,  making  a memorandum 
of  the  weights  in  a note-book.  Add  rather  more  strong 
sulphuric  acid  than  may  be  considered  sufficient  to  convert 
the  chloride  into  acid  sulphate  of  sodium.  Heat  the  cru- 
cible graduall}^,  the  flame  being  first  directed  against  the 
side  of  the  crucible  to  avoid  violent  ebullition,  until  fumes 
of  acid  cease  to  be  evolved,  towards  the  end  of  the  operation 
dropping  in  one  or  two  fragments  of  carbonate  of  ammonium 
to  facilitate  complete  expulsion  of  all  excess  of  acid.  When 
cold,  weigh  the  crucible  and  contents.  The  weight  of  the 
crucible  having  been  deducted,  the  amount  of  sulphate 
obtained  should  be  the  exact  equivalent  of  the  quantity  of 
chloride  of  sodium  employed. 

2NaCl  + H,SO,  = Na^SO,  -f  2HC1. 

Ill  142 


Proportional  weights  of  equivalent  quantities  of  sodium  and 
its  salts. 


Metal 

. Na, 

46 

Oxide  (“  soda”) 

, Na,0  .... 

62 

Hydrate  (“  caustic  soda”)  . . , 

. 2NaHO  . . . 

80 

Carbonate  (anh3^drous)  . . . , 

. Na3C03  . . . 

106 

Carbonate  (cr^-stals)  . . . . , 

. Na,CO„10H^O  . 

286 

Bicarbonate 

. 2NaHC03  . . 

168 

Chloride 

. 2NaCl  .... 

in 

Sulphate  (anh3^drous)  .... 

. Na^SO,  . . . 

142 

Sulphate  (crystals) 

. Na^SO^lOH^O  . 

322 

502 


QUANTITATIVE  ANALYSIS. 


AMMONIUM. 

Salts  of  ammonium  are,  for  purposes  of  quantitative 
analysis,  generally  converted  into  the  double  chloride  of 
ammonium  and  platinum  (PtCl42NH^Cl),  the  details  of 
manipulation  being  the  same  as  those  observed  in  the  case 
of  potassium.  About  0.15  grm.  of  pure,  white,  dry  chlo- 
ride of  ammonium  may  be  taken  for  experiment. 


COMPOSITION  OF  THE  PLATINUM  SALT. 


In  1 molecule. 

In  100  parts. 

Ft  . . 

. 198 

. . 198  . . 

. 44.30 

Cls  . . 

. 35.5  X 6 . 

. . 213  . . 

. 47.64 

N,  . . 

. 14.0  X 2 . 

. . 28  . . 

. 6.27 

Hs  . . 

1.0  X 8 . 

8 . . 

. 1.79 

447 

100.00 

PtCl,  . , 

. 340 

. . 340  . . 

. 76.06 

2NH,C1 

. 53.5  X 2 . 

. . 107  . . 

. 23.94 

447 

100.00 

The  proportion  of  nitrogen,  ammonium,  or  chloride  of 
ammonium  in  the  double  chloride  may  also  be  ascertained 
from  the  Tveight  of  platinum  left  on  igniting  the  double 
chloride;  for  this  purpose  heat  must  be  applied  slowly, 
or  platinum  will  be  mechanically  carried  otf  with  the  gas- 
eous products  of  decomposition 


Proportional  weights  of  equivalent  quantities  of  ammoniac al 
compounds. 


Ammonia  (gas) 

. 2NH,  .... 

. 34 

Ammonium 

. (NHJ,?  . . . 

. 36 

Chloride  of  ammonium  . . 

. 2NH,C1  . . . 

. 107 

Platinum  salt 

. PtCl,,2NH,Cl  . 

. 447 

Carbonate  of  ammonium^^ 

. (NJI.,C,OJ  - 2 

. 118 

Sulphate  of  ammonium  . . 

. (NH,),SO,  . . 

. 132 

BARIUM. 

Barium  is  estimated  in  the  form  of  anhydrous  sulphate 
of  barium  (BaSOJ. 

Process. — Dissolve  0.3  or  0.4  of  pure  crystallized  and 
dried  chloride  or  nitrate  of  barium  in  about  half  a litre  of 
water  in  a beaker,  heating  to  incipient  ebullition,  and 
slightly  acidulating  with  hydrochloric  or  nitric  acid.  Add 


GRAVIMETRIC  ESTIMATION  OF  BARIUM.  503 


diluted  sulphuric  acid  (prepared  some  days  previously,  so 
that  sulphate  of  lead  may  have  deposited)  so  long  as  a 
precipitate  forms,  keep  the  mixture  hot  for  some  time,  set 
aside  for  half  an  hour,  pass  the  supernatant  liquid  through 
a filter,  gently  boil  the  residue  two  or  three  times  with 
more  water;  finally  collect  the  precipitate  on  the  filter, 
removing  adherent  particles  from  the  beaker  by  the  finger, 
and  cleansing  by  a stream  of  hot  water  from  the  wash- 
bottle.  The  precipitate  must  be  washed  with  hot  water 
until  the  filtrate  ceases  to  turn  litmus  paper  red,  or  give 
any  cloudiness  when  tested  with  chloride  of  barium.  The 
filter  and  sulphate  of  barium,  having  thoroughly  drained, 
is  dried  in  a warm  place,  commonly  by  supporting  the 
funnel  in  an  inverted  bottomless  beaker  over  a sand-bath 
or  hot  plate. 

The  sulphate  of  barium  is  now  removed  from  the  filter, 
heated  to  drive  off*  every  trace  of  moisture,  and  weighed. 
This  is  accomplished  by  placing  a weighed  porcelain  cru- 
cible (and  cover)  on  a sheet  of  glazed  paper,  holding  the 
filter  over  it,  and  carefully  transferring  the  precipitate  ; 
the  sides  of  the  filter  are  then  gently  rubbed  together  and 
detached  powder  dropped  into  the  crucible,  the  paper 
folded,  encased  in  two  or  three  coils  of  one  end  of  a plati- 
num wire  and  burnt  over  the  crucible,  ash  and  any  particles 
in  the  sheet  of  paper  dropped  into  the  sulphate  of  barium, 
the  open  crucible  exposed  over  a fiame  till  its  contents  are 
quite  white,  covered,  cooled,  and  weighed. 


Formulae.  Molecular 
weights. 


Chloride  of  barium 

. 

. BaCl,  . . 

. 208 

Nitrate  of  barium 

. • . • 

. Ba2N03  . 

261 

Sulphate  of  barium 

. . . . 

. BaSO,  . . 

233 

Composition  of  Sulphate  of  Barium. 

In  one 

In  100 

molecule. 

parts. 

Ba 

131  . . 

. . 131  . . 

68.80 

S 

32  . . 

. . 32  . . 

13.73 

0. 

16x4. 

. . 64  . . 

27.47 

233 

100.00 

In  these  experiments  it  is  unnecessary  to  take  filter-ash 
into  account.  Faults  of  manipulation  cause  far  greater 
errors. 


504 


QUANTITATIVE  ANALYSIS. 


CALCIUM. 

Calcium  is  usually  thrown  out  of  solution  in  the  form  of 
oxalate,  the  precipitate  ignited,  and  the  resulting  carbonate 
w^eighed. 

Process, — Dissolve  0.3  or  0.4  of  dried  colorless  crystals 
of  calc-spar  in  about  a third  of  a litre  of  water  acidulated 
with  h^uirochloric  acid,  heat  the  solution  to  near  the  boil- 
ing-point, add  excess  of  solution  of  oxalate  of  ammonia, 
then  ammonia  until,  after  stirring,  the  liquid  smells  strongly 
ammoniacal;  set  aside  in  a warm  place  for  twelve  hours. 
Carefully  pour  off  the  supernatant  liquid,  passing  it  through 
a filter ; add  hot  water  to  the  precipitate,  set  aside  for  half 
an  hour,  again  decant,  and,  after  once  more  washing,  trans- 
fer the  precipitate  to  the  filter,  allowing  all  contained  fluid 
to  pass  through  before  a fresh  portion  is  added.  Wash 
the  precipitate  with  hot  water,  avoiding  a rapid  stream,  or 
the  precipitate  may  be  driven  through  the  pores  of  the  I 
paper.  Diy,  transfer  to  a weighed  crucible,  and  incinerate,  | 
as  described  for  sulphate  of  barium,  and  slowlj^  heat  the  i 
precipitate  till  the  bottom  of  the  crucible  is  just  visibly 
red  when  seen  in  the  dark.  As  soon  as  the  residue  is  white,  | 
or  only  faintly  gray,  remove  the  lamp,  cool,  and  weigh. 

The  resulting  carbonate  of  calcium  should  have  the  same 
weight  as  the  calc-spar  from  which  it  was  obtained.  If 
loss  has  occurred,  carbonic  acid  gas  has  probably  escaped.  . 
In  that  case  moisten  the  residue  with  water,  and  after  a 1 
few  minutes  test  the  liquid  with  red  litmus  or  turmeric 
paper;  if  an  alkaline  reaction  is  noticed,  it  is  due  to  the 
presence  of  caustic  lime.  Add  a small  lump  of  carbonate 
of  ammonium,  evaporate  to  diyness  over  a water-bath,  and 
again  ignite,  this  time  being  careful  not  to  go  beyond  the 
prescribed  temperature.  The  treatment  may,  if  necessary,  ^ 
be  repeated. 

Proportional  weights  of  equivalent  quantities  of  calcium 
salts. 

Oxide  (quicklime) CaO 56 

Hydrate  (slaked)  lime  . . . . . Ca2HO  ....  74  ' 

Carbonate CaCOg  . . . . 100 

Sulphate  (anlij^drous) CaSO^  . . . . 136  il 

Sulphate  (crystalline  or  precipCd) . CaSO.,  2H2O  . .172  ^ 

Chloride CaCl^  ....  Ill  ' 

Phosphate  (of  bone) (Cag2POJ310 -r  3 103.3  •: 

Superphosphate CaH^2PO^  . . . 234  N 


GRAVIMETRIC  ESTIMATION  OF  MAGNESIUM.  505 


MAGNESIUM. 

Process  1. — The  light  or  heavy  carbonate  of  magnesium 
of  pliaraiacj^  may  be  estimated  by  heating  a weighed  quan- 
tity to  redness  in  a porcelain  crucible.  If  it  has  the  com- 
position indicated  by  the  formula  given  in  the  British 
Pharmacopoeia  (SMgCO.^,  Mg2HO,4H.^O),  it  will  3deld  42 
per  cent,  of  magnesia  (MgO).  According  to  that  work, 
the  purity  of  even  sulphate  of  magnesium  (MgSO^, 
may  be  determined  by  boiling  a weighed  quantity  with 
excess  of  carbonate  of  sodium,  collecting  the  precipitate, 
washing,  dr^dng,  igniting,  and  weighing  the  resulting  mag- 
nesia (MgO).  The  crystallized  sulphate  should  afford 
16.26  per  cent,  of  oxide.  The  official  solution  of  carbonate 
of  magnesium  in  carbonic  acid  water  {Liquor  Magnesise 
Garhonatis^  B.  P.)  should  yield  five  grains  of  pure  oxide  of 
magnesium  per  fluidounce. 

Process  2. — The  general  form  in  which  magnesium  is 
precipitated  is  as  phosphate  of  ammonium  and  magnesium 
(MgNH^PO^,  6H2O)  ; this,  by  heat,  is  converted  into  pyro- 
phosphate of  magnesium  (Mg2P20-).  Accurately  weigh  a 
small  quantity  (0.4  to  0.5)  of  pure  dry  crystals  of  sulphate 
of  magnesium,  dissolve  in  two  or  three  hundred  cubic 
centimetres  of  cold  water  in  a beaker,  add  chloride  of  am- 
monium, ammonia,  and  phosphate  of  sodium  or  ammo- 
nium, agitate  with  a glass  rod  (without  touching  the  sides 
of  the  vessel,  or  crystals  will  firmly  adhere  to  the  rubbed 
portions),  and  set  aside  for  twelve  hours.  Collect  on  a 
filter,  wash  the  precipitate  with  water  containing  a tenth 
of  its  volume  of  the  strongest  solution  of  ammonia,  until 
the  filtrate  ceases  to  give  a precipitate  with  an  acidulated 
solution  of  nitrate  silver.  Dry,  transfer  to  a crucible,  burn 
the  filter  in  the  usual  way,  heat  slowly  to  redness,  cool,  and 
weigh. 

Proportional  weights  of  equivalent  quantities  of  magnesium 

salts. 

Pyrophosphate  . . Mg^P^O^ 222 

Sulphate  ....  2(MgS04,  TH^O) 492 

Oxide 2(MgO) 80 

Official  carbonate  . (3MgCO  .,  Mg2HO,  41T,.0) 2 . 191 

43 


506 


QUANTITATIVE  ANALYSIS. 


ZINC. 

Zinc  is  usually  estimated  as  oxide  (ZnO),  occasionallj^ 
as  sulphide  (ZnS). 

Process. — Dissolve  a weighed  quantity  (0.5  to  0.6)  of 
sulphate  of  zinc  in  about  half  a litre  of  water  in  a beaker, 
heat  to  near  the  boiling-point,  add  carbonate  of  sodium  in 
slight  excess,  boil,  set  aside  for  a short  time  ; pass  the 
supernatant  liquid  through  a filter,  gently  boil  the  precipi- 
tate with  more  water,  again  decant ; repeat  these  opera- 
tions two  or  three  times  ; collect  the  precipitate  on  the 
filter,  wash,  dry,  transfer  to  a crucible,  incinerate,  ignite, 
cool,  and  weigh.  281  (=molec.  weight)  of  sulphate  should 
yield  81  (=molec.  weight)  of  oxide. 

MANGANESE. 

To  ascertain  its  value  for  evolving  chlorine  from  hydro- 
chloric acid  a weighed  quantity  of  finely  powdered  black 
oxide  of  manganese  is  heated  in  a small  flask  with  pure  hy- 
drochloric acid,  and  the  resulting  chlorine  conveyed  into  a 
U-tube  containing  solution  of  iodide  of  potassium.  The 
amount  of  iodine  thus  freed  is  estimated  by  the  volumetric 
solution  of  hyposulphite  of  sodium.  127  of  iodine  indi- 
cate 35.5  of  chlorine. 


ALUMINIUM. 

Aluminium  is  always  precipitated  as  hydrate  (AlgfiHO) 
and  weighed  as  oxide  (AI2O3). 

Process. — Dissolve  about  two  grammes  of  pure  dry  am- 
monium-alum in  half  a litre  of  water,  heat  the  solution,  add 
chloride  of  ammonium  and  a slight  excess  of  ammonia, 
boil  gently  till  the  odor  of  ammonia  has  nearly  disap- 
peared, set  aside  for  the  hydrate  to  deposit,  pass  the  super- 
natant liquid  through  a Alter,  wash  the  precipitate  three 
or  four  times  by  decantation,  transfer  to  the  filter,  finish 
the  washing,  dry,  burn  the  filter,  ignite  in  a covered  cruci- 


ble, and  weigh. 

Al,3SO„  (NHJ,SO„  24H^O 907 

AI2O3 103 

Per  cent,  of  Al^Og  yielded  by  ammonium-alum  . 11.356 


GRAVIMETRIC  ESTIMATION  OP  IRON.  50t 


QUESTIONS  AND  EXERCISES. 

' 1027.  Give  details  of  the  manipulations  observed  in  gravimetrically 
estimating  salts  of  potassium  or  ammonium. 

1028.  What  quantity  of  chloride  of  sodium  is  contained  in  a sample 
of  rock-salt  0.351  gramme  of  which  yields  0.44  of  sulphate  of  sodium  ? 
— Ans.  100  per  cent.  (It  is  absolutely  pure.) 

1029.  To  what  amount  of  the  official  alum  is  0.894  of  a gramme  of 
the  double  chloride  of  platinum  and  ammonium  equivalent? — A^is. 
1.814  gramme. 

1030.  Find  the  weight  of  sulphate  of  barium  obtainable  from 
0.522  of  nitrate. — Ans.  0.466. 

1031.  Describe  the  usual  method  by  which  salts  of  calcium  are 
estimated. 

1032.  By  what  quantitative  processes  may  the  official  salts  of 
magnesium  be  analyzed  ? 

1033.  Calculate  the  proportion  of  pure  sulphate  of  zinc  in  a sample 
of  crystals  0.574  of  which  yield  0 161  of  oxide  — Ans.  99.3  per  cent. 

1034.  Ascertain  the  weight  of  alumina  (AI^Ojj)  which  should  be 
obtained  from  1.814  gramme  of  ammonium-alum. 


IRON. 

Iron  and  its  salts  are  gravimetrically  estimated  in  the 
form  of  ferric  oxide  (Fe.^Og). 

Compounds  containing  organic  acidulous  radicals  are 
simply  incinerated,  and  the  resulting  oxide  weighed.  Thus 
1 gramme  of  the  official  citrate  of  iron  and  ammonium 
{Ferri  et  Ammonise  Oitras.^  B.  P.)  incinerated,  with  expo- 
sure to  air,  leaves  not  less  than  .27  of  ferric  oxide.  A small 
quantity  of  the  salt  is  weighed  in  a tared  covered  porcelain 
crucible,  flame  cautiously  applied  until  vapors  cease  to  be 
evolved,  the  lid  then  removed,  the  crucible  slightly  inclined 
and  exposed  to  a red  heat  until  all  carbonaceous  matter 
has  disappeared.  The  residual  ferric  oxide  is  then  weighed. 
The  tartrate  of  potassium  and  iron  {{Ferrum  Tartaratum^ 
B.  P.)  is  treated  in  the  same  manner,  except  that  the  ash 
must  be  washed  and  again  heated  before  weighing,  in  order 
to  remove  carbonate  of  potassium  produced  during  incine- 
ration ; 5 grammes  should  3deld  1.5  gramme  of  ferric  oxide. 

From  other  compounds  of  iron,  soluble  in  water  or  acid, 
the  metal  is  precipitated  in  the  form  of  hydrate  (Fe.^6HO) 
by  solution  of  ammonia,  and  converted  into  oxide  (Fe.^Og) 
by  ignition.  Dissolve  a piece  (about  0.2)  of  the  purest 
iron  obtainable  (piano  wire),  accurately  weighed,  in  water 


508 


QUANTITATIVE  ANALYSIS. 


acidulated  with  hydrochloric  acid  ; add  a few  drops  of 
nitric  acid  and  gently  boil ; pour  in  excess  of  ammonia, 
stir,  set  aside  till  the  ferric  hydrate  has  deposited,  pass  the 
supernatant  liquid  through  a filter,  treat  the  precipitate 
three  or  four  times  wdth  boiling  water ; transfer  to  the 
filter,  wasli  till  the  filtrate  yields  no  trace  of  chlorine  (for 
chloride  of  ammonium  will  decompose  ignited  ferric  oxide, 
with  volatilization  of  ferric  chloride),  dry  and  ignite  as 
usual,  and  weigh.  Iron  in  the  official  solutions  {Liquor 
Ferri  Fercliloridi  Fortior^  Liquor  Ferri  Pernitratis^  and 
Liquor  Ferri  Persulphatis)  may  be  estimated  by  this 
general  process. 

The  proportion  of  metallic  iron  in  a mixture  of  iron  and 
oxides  of  iron  may  be  determined  by  digestion  in  a strong 
solution  of  iodine  in  iodide  of  potassium,  which  attacks 
the  metal  only.  The  reduced  iron  of  pharmacy  {Ferrum 
Bedactum)  is  in  good  condition  so  long  as  it  contains,  as 
show^n  by  this  method,  half  its  weight  of  free  metal. 

Pi'oportional  weights  of  equivalent  quantities  of  iron  and 
its  salts. 


Metal 

.Fe, 

. 112 

Ferric  oxide  . . . 

• Fe,0, 

. 160 

Ferric  hydrate  . . 

. Fe,6HO  . . . . 

. 214 

Ferric  chloride  . . 

. Fe,Cl, 

. 325 

Ferric  sulphate  . . 

. Fe„3SO,  . . . . 

. 400 

Ferrous  sulphate  . 

. 2(FeSO,,  TH,0)  . 

. 556 

ARSENICUM. 

Arsenic  (ASy03)  is  usually  estimated  volumetrically  (vide 
p.  489).  With  certain  precautions  arsenic um  ma}^  also  be 
precipitated  and  weighed  as  sulphide  (As^Sg). 

Process. — The  pure,  white,  massive  arsenic  (about  0.2) 
is  dissolved  in  a flask  in  a small  quantit}^  of  water  contain- 
ing bicarbonate  of  sodium  or  potassium,  the  liquid  being 
heated.  A slight  excess  of  h^^drochloric  acid  is  then  added, 
and  sulphuretted  hydrogen  gas  passed  through  the  solu- 
tion so  long  as  a precipitate  falls,  the  mouth  of  the  flask 
being  stopped  by  a plug  of  cotton-wool  (to  prevent  undue 
access  of  air  and  consequent  decomposition  of  the  gas, 
resulting  in  precipitation  of  sulphur).  The  mixture  is 
warmed  in  the  flask  and  carbonic  acid  gas  passed  through 
it  until  the  odor  of  sulphuretted  hydrogen  has  nearly  dis- 
appeared ; the  precipitate  collected  on  a tared  filter,  washed 


ANTIMONY  — COPPER. 


509 


as  qniekl}^  as  possible  with  hot  water  containing  a little 
sulphuretted  hydrogen,  dried  in  a water-oven  and  weighed. 
198  parts  of  arsenic  should  yield  246  of  sulphide  of  arseni- 
cum. 


ANTIMONY. 

The  metal  is  precipitated  in  the  form  of  sulpliide  (Sb^S.J, 
with  the  precautions  observed  in  estimating  arsenicum — a 
small  quantity  of  tartaric  acid,  as  well  as  hj^drochloric, 
being  added,  to  prevent  the  precipitation  of  an  oxj^salt. 
If  the  sulphuretted  hydrogen  be  passed  through  a hot  so- 
lution,  the  particles  of  precipitate  aggregate  better,  and 
the  latter  may  be  more  quickly  filtered  out  and  washed. 
The  experiment  may  be  performed  on  about  half  a gramme 
of  pure  tartar-emetic  : the  salt  should  yield  nearly  half  its 
weight  (49.56  per  cent.)  of  sulphide.  According  to  Fre- 
senius,  the  sulphide  dried  at  lOO'^  C.  still  contains  2 per 
cent,  of  water,  and  must  be  heated,  in  a current  of  carbonic 
acid  gas,  until  it  turns  from  an  orange  to  a black  color, 
before  all  moisture  is  expelled.  In  the  British  Pharmaco- 
peeia  the  purity  of  tartar-emetic  {Antimonium  Tartaratum)^ 
and  the  strength  of  solution  of  chloride  of  antimony  {Li- 
quor Antimonii  Ghloridi)^  are  determined  by  the  above 
process. 


COPPER. 

Copper  is  precipitated  from  its  solutions  and  weighed 
either  (I)  as  metal  (Ciq),  or  (2)  as  oxide  (CuO). 

Process  I. — Dissolve  about  half  a gramme  of  dry  crystal- 
lized sulphate  of  copper  in  a small  quantity  of  water,  in  a 
tared  porcelain  crucible  or  beaker,  acidulate  with  hydro- 
chloric acid,  introduce  a fragment  or  two  of  pure  zinc, 
cover  the  vessel  with  a watch-glass,  and  set  aside  till  evo- 
lution of  hydrogen  has  ceased  and  the  still  acid  liquid  is 
colorless.  The  copper  is  then  washed  with  hot  water  by 
decantation  until  no  trace  of  acid  remains,  the  precipitate 
drained,  rinsed  with  strong  spirit  of  wine,  dried  in  the 
water-oven,  and  weighed. 

Process  2. — About  three-fourths  of  a gramme  of  sulphate 
of  copper  is  accurately  weighed,  dissolved  in  half  a litre  of 
water,  the  liquid  boiled ; dilute  solution  of  potash  or  soda 
is  then  added  till  no  more  precipitate  falls,  ebullition  con- 
tinued for  a short  time,  and  the  beaker  set  aside  ; the  super- 
natant liquid  is  decanted,  the  precipitate  boiled  with  water 

43* 


510 


QUANTITATIVE  ANALYSIS. 


twice  or  thrice,  collected  on  a filter,  washed,  dried,  trans- 
ferred to  a crucible,  the  filter  incinerated,  and  its  ash  moist- 
ened with  a drop  of  nitric  acid  ; the  whole  is  finally  heated 
strongly,  cooled,  and  weighed. 

249.5  parts  of  sulphate  of  copper  ^deld  ^9.5  of  oxide,  or 
63.5  of  metal. 


BISMUTH. 

Dissolve  0.3  or  0.4  of  pure  oxycarbonate  of  bismuth 
(26402003,1120)  (Bismuthi  Garbonas^  B.  P.)  in  a small 
quantity  of  h^^drochloric  acid,  dilute  with  water  slightly 
acidulated  b^^  hydrochloric  acid,  pass  excess  of  sulphuretted 
hydrogen  through  the  liquid,  collect  the  precipitate  on  a 
tared  filter,  wash,  dry  at  100*^  C.,  and  weigh.  The  sul- 
phide must  not  be  exposed  too  long  in  the  water-oven,  or 
it  will  increase  in  w^eight  owing  to  absorption  of  oxygen  ; 
hence  it  should  be  tested  in  the  balance  every  half-hour 
during  desiccation.  5n  of  oxycarbonate  should  yield  512 
of  sulphide  (Bi2S3).  The  strength  of  the  official  solution 
of  citrate  of  bismuth  and  ammonium  {Liquor  Bismuthi  et 
Ammonise  Gitratis^  B.  P.)  is  determined  by  this  process. 
“Three  fluidrachms  of  the  solution,  mixed  with  an  ounce 
of  distilled  water,  and  treated  with  sulphuretted  hydrogen 
in  excess, yield  a black  precipitate,  which,  collected,  washed, 
and  dried,  weighs  9.92  grains.  One  fluidrachm  yields  three 
grains  of  oxide  of  bismuth.’’  The  atomic  weight  of  bismuth 
is  208. 


MERCURY. 

This  element  may  be  (1)  isolated  and  estimated  in  the 
form  of  metal,  or  precipitated  and  weighed  as  (2)  mercu- 
rous chloride,  or  (3)  mercuric  sulphide. 

Process  1. — The  process  by  which  the  metal  itself  is 
separated  is  one  of  distillation,  into  a bulb  surrounded  by 
water.  About  half  a metre  of  the  difficultly  fusible  Ger- 
man glass  known  as  combustion-tubing  is  sealed  at  one  end 
after  the  manner  of  a test-tube  ; a mixture  of  bicarbonate 
of  sodium  and  dry  chalk  is  then  dropped  into  the  tube  to 
the  height  of  two  or  three  centimetres,  and,  next,  several 
small  fragments  of  quicklime  so  as  to  occupy  another  centi- 
metre ; a mixture  of  about  a gramme  of  pure  calomel  or 
corrosive  sublimate  with  enough  powdered  quicklime  to 
occupy  10  or  12  centimetres  of  the  tube  is  added,  then  the 
lime-rinsings  of  the  mixing-mortar,  a la^^er  of  a few  centi- 


GRAVIMETRIC  ESTIMATION  OF  MERCURY.  511 


metres  of  powdered  quicklime,  and  finally  a plug  of  asbestos 
(a  fibrous  mineral  unaffected  by  beat).  The  whole  powder 
should  occupy  two-thirds  of  the  length  of  the  tube.  The 
part  of  the  tube  just  above  the  asbestos  is  now  softened  in 
the  blowpipe-flame  and  drawn  out  about  a decimetre  to  the 
diameter  of  a narrow  quill ; it  is  again  drawn  out  to  the 
same  extent  at  a point  about  two  or  three  centimetres 
nearer  the  mouth,  and  any  excess  of  tubing  cut  off.  The 
bulb  thus  formed  may  be  enlarged  by  softening  and  blow- 
ing. The  tube  is  next  softened  at  a point  close  to  but  an- 
terior to  the  asbestos,  and  bent  nearly  to  a right  angle  ; 
the  tube  is  then  softened  close  to  the  bulb  and  slightly  bent 
so  that  the  bulb  may  be  parallel  with  the  large  tube ; then 
softened  on  the  other  side  of  the  bulb,  and  the  narrow  ter- 
minal tube  bent  to  a right  angle,  so  that,  the  tube  being 
held  in  a horizontal  position,  the  bulb  may  be  sunk  in  water, 
and  the  terminal  tube  point  upwards.  The  long  tube  is  now 
laid  in  the  gas-furnance  found  in  most  laboratories,  a basin 
so  placed  that  the  bulb  of  the  apparatus  may  be  cooled  by 
being  surrounded  by  w'ater,  the  part  of  the  tube  occupied 
by  asbestos  heated  to  redness,  and  the  flame  slowly  length- 
ened until  the  whole  tube  is  red-hot.  Under  these  circum- 
stances the  mercurial  compound  volatilizes,  is  decomposed 
by  the  lime,  and  its  acidulous  radical  fixed,  the  mercury 
carried  in  vapor  to  and  condensed  in  the  bulb,  the  carbonic 
acid  gas  evolved  from  the  bicarbonate  of  sodium  and  chalk 
washing  out  the  last  portions  of  mercuiy -vapor  from  the 
tube.  When  the  distillation  is  considered  to  be  complete, 
the  dish  of  water  is  removed,  the  bulb  dried,  and  then  de- 
tached by  help  of  a file  at  a point  beyond  any  sublimate  of 
mercury.  The  bulb  is  lastly  weighed,  the  mercury  shaken, 
or  dissolved  out,  and  the  tube  again  dried  and  weighed. 

Process  2. — The  process  by  which  mercury  is  separated 
in  the  form  of  calomel  consists  in  adding  hydrochloric 
and  phosphorous  acids  {vide  p.  312)  to  an  aqueous  or  even 
acid  solution  of  a weighed  quantity  of  the  mercurial  com- 
pound, setting  the  mixture  aside  for  twelve  hours,  collecting 
the  precipitate  on  a tared  filter,  washing,  drying  at  100"^ 
C.,  and  weighing  (Rose).  The  experiment  may  be  tried  on 
half  a gramme  to  a gramme  of  corrosive  sublimate. 

Process  3. — Two  or  three  decigrammes  of  corrosive  subli- 
mate are  dissolved  in  water,  the  solution  acidulated  with 
hydrochloric  acid,  excess  of  sulphuretted  hydrogen  passed, 
the  precipitate  collected  on  a tared  filter,  washed  with  cold 
water,  dried  at  100^  C.,  and  weighed. 


512 


QUANTITATIVE  ANALYSIS. 


Proportional  weights  of  equivalent  quantities  of  mercury 
and  its  salts. 


Metal 

. Hg  . . 

. . 200 

Mercurous  chloride 

. HgCl  . 

. . 235.5 

Mercuric  chloride  . . 

. HgCl  . 

. . 271 

Mercuric  sulphide  . . 

. HgS  . . 

. . 232 

LEAD. 

Lead  is  generally  estimated  either  as  (1)  oxide,  (2)  sul- 
phate, or  (3)  chromate. 

Process  1. — Weigh  out  one  or  two  grammes  of  pure 
acetate  of  lead  in  a covered  crucible,  previously  tared,  and 
heat  slowly  until  no  more  vapors  are  evolved.  Remove 
the  lid,  stir  down  the  carbonaceous  mass  with  a clean  iron 
wire,  and  keep  the  crucible  in  the  flame  so  long  as  any  car- 
bon remains  unconsumed.  Introduce  some  fragments  of 
fused  nitrate  of  ammonium,  and  again  ignite  until  no 
metallic  lead  remains,  and  all  excess  of  the  nitrate  has  been 
decomposed.  Cool  and  weigh  the  resulting  oxide  (PbO). 

Process  2. — Dissolve  0.4  or  0.5  of  a gramme  of  acetate  of 
lead  in  a small  quantity  of  water,  drop  in  diluted  sulphuric 
acid,  add  to  the  mixture  twice  its  bulk  of  methylated  spirit 
of  wine,  and  set  aside.  Decant  the  supernatant  liquid,  col- 
lect the  sulphate  on  a filter,  wash  with  spirit,  dry,  transfer 
to  a porcelain  crucible,  removing  as  much  of  the  sulphate 
as  possible  from  the  paper,  incinerate  on  the  crucible-lid 
(not  in  a platinum  coil,  for  the  particles  of  reduced  lead 
would  unite  with  the  platinum  by  fusion),  ignite,  cool,  and 
weigh. 

Process  3. — About  half  a gramme  of  acetate  of  lead  is 
dissolved  in  two  or  three  hundred  c.  c.  of  water,  acetic  acid 
added,  and  then  solution  of  red  chromate  of  potassium. 
Collect  the  precipitate  on  a tared  filter,  wash,  dry  at  100° 
C.,  and  weigh. 


Molecular  weights  of  salts  of  lead. 


Metal  . . . 

. Pb 

207 

Acetate  . . 

. Pb2C,H30,,3H,0  . 

379 

Oxide  . . 

. PbO  . ‘ . 

223 

Sulphate  . , 

, PbSO, 

303 

Chromate  . , 

, PbCrO,  .... 

323.5 

CUPEL LATION. 


513 


SILVER. 

Compounds  of  silver  which  are  readily  decomposed  by 
heat  are  estimated  in  the  form  of  (1)  metal,  others  usually  as 
(2)  chloride  (AgCl),but  sometimes  as  (3)  cyanide  (AgNC). 

Process  1. — Heat  about  a gramme  of  oxide  of  silver  (Ag^O) 
in  a tared  crucible,  cool,  and  weigh.  232  of  oxide  yield 
216  of  metal.  “ 29  grains  heated  to  redness  yield  27  grains 
of  metallic  silver.’^ — Brit.  Pharm. 

Process  2. — Dissolve  0.4  or  0.5  of  pure  dry  crystals  of 
nitrate  of  silver  in  water,  acidulate  with  two  or  three  drops 
of  nitric  acid,  slowly  add  hydrochloric  acid,  stirring  rap- 
idly, until  no  more  precipitate  falls.  Pour  off  the  super- 
natant liquid  through  a filter,  wash  the  chloride  of  silver 
once  or  twice  with  hot  water,  transfer  to  the  filter,  com- 
plete the  washing,  and  dry.  After  removing  as  much  as 
possible  of  the  precipitate  from  the  paper  to  the  crucible, 
burn  the  filter,  letting  its  ash  fall  on  the  inverted  lid  of  the 
crucible,  moisten  with  a drop  of  nitric  acid,  warm,  add  a 
drop  of  hydrochloric  acid,  evaporate  to  dryness,  replace 
the  lid  on  the  crucible,  ignite  the  whole,  until  the  edges  of 
the  mass  of  chloride  begin  to  fuse  ; cool  and  weigh.  170 
of  nitrate  yield  143.5  of  chloride.  According  to  the 
British  Pharmacopoeia,  10  parts  of  nitrate  should  thus 
yield  8.44  of  chloride,  and  the  filtrate  from  the  chloride 
evaporated  to  dryness  should  leave  no  residue,  indicating 
absence  of  nitrates  of  potassium  or  sodium  and  other  simi- 
lar adulterants. 

Pi'ocess  3 Cyanide  of  silver  may  be  collected  on  a tared 

filter  and  dried  at  100°  C.  170  of  nitrate  yield  134  of 
cyanide. 

Silver  and  its  salts  may  be  volumetrically  estimated  by 
a standard  solution  of  chloride  of  sodium. 

Cupellatwn. — The  amount  of  silver  in  an  alloy  may  be  also  deter- 
mined by  a dry  method.  The  metal  is  folded  in  a piece  of  thin  sheet 
lead,  placed  on  a cupel  (cupella,  little  cup,  made  of  compressed  bone- 
earth)  and  heated  in  a furnace,  the  cupel  being  protected  from  the 
direct  action  of  flame  by  a muff-shaped,  or,  rather,  oven-shaped  case 
termed  a mufile.  The  metals  melt,  the  baser  become  oxidized,  the 
oxide  of  lead  fusing  and  dissolving  the  other  oxides  ; the  fluid  oxides 
are  absorbed  by  the  porous  cupel,  a button  of  pure  silver  remaining. 
An  alloy  suspected  to  contain  95  per  cent,  of  silver  requires  about 
3 times  its  weight  of  lead  for  successful  cupellation  ; if  92^  per  cent. 
(English  silver  coin),  between  5 and  6 times  as  much  lead  is  necessary. 


514 


QUANTITATIVE  ANALYSIS. 


QUESTIONS  AND  EXERCISES. 

1035.  Explain  the  gravimetric  process  by  which  the  strength  of 
the  oflBcial  solutions  of  ferric  chloride,  nitrate,  and  sulphate  are  de- 
termined. 

1036.  Mention  the  various  amounts  of  ferrous  and  ferric  salts 
equivalent  to  100  parts  of  metal. 

1037.  State  the  precautions  necessary  to  be  observed  in  estimating 
arsenicum  or  antimony  in  the  form  of  sulphide. 

1038.  In  what  form  are  the  official  compounds  of  bismuth  weighed 
for  quantitative  purposes  ? 

1039.  Give  an  outline  of  the  process  by  which  mercury  may  be 
isolated  from  its  official  preparations  and  weighed  in  the  metallic 
condition. 

1040.  Describe  three  methods  for  the  quantitative  analysis  of  salts 
of  lead ; and  the  weights  of  the  respective  precipitates,  supposing 
0.56  of  crystallized  acetate  to  have  been  operated  on  in  each  case. 

1041.  Describe  the  process  by  which  silver  is  estimated  in  the 
forms  of  metal,  chloride,  and  cyanide. 

1042.  What  proportions  of  nitrate  of  silver  are  indicated,  respec- 
tively, by  15  of  metal,  9.8  of  chloride,  and  8.1  of  cyanide  ? 

1043.  Define  cupellation. 


ESTIMATION  OF  THE  ACIDULOUS 
EADICALS  OF  SALTS. 

CHLORIDES. 

Free  chlorine  (chlorine-water)  and  compounds  which  by 
action  of  acids  3deld  free  chlorine  (Chlorinated  Lime,  Chlo- 
rinated Soda,  and  their  official  Solutions)  are  estimated 
volumetrically  hy  a standard  solution  of  hyposulphite  of 
sodium  ( vide  p.  493).  The  amount  of  combined  chlorine 
in  pure  chlorides  (HCl,NaCl)  ma}^  also  be  determined  b}^ 
A'Olumetric  analy^sis  with  a standard  solution  of  nitrate  of 
silver  (p.  486). 

Combined  chlorine  is  gravimetrically  estimated  in  the 
form  of  chloride  of  silver,  the  operations  being  identical 
with  that  just  described  for  silver  salts  ; 58.5  parts  of  pure,  !. 
colorless,  crystallized  chloride  of  sodium  (rock-salt)  ^deld  ! 
143.5  of  chloride  of  silver.  j 

I 

IODIDES.  1 

Free  iodine  is  estimated  volumetrically  by  solution  of  j 
hyposulphite  of  sodium  {vide  p.  493)..  ' 

Combined  iodine  is  determined  gravimetrically  in  the  j 
form  of  iodide  of  silver,  the  operations  being  conducted  as  j' 


BROMIDES  — CYANIDES  — NITRATES. 


515 


with  chloride  of  silver.  Iodide  of  potassium  may  be  used 
for  an  experimental  determination  : KI  = 166  should  ^deld 
Agl  = 235.  Of  the  official  iodide  of  cadmium  (Gadmii 
lodidiim^  B.  P.)  it  is  stated  that  “ ten  grains  dissolved  in 
water,  and  nitrate  of  silver  added  in  excess,  give  a pre- 
cipitate which,  when  washed  wdth  water  and  afterwards 
with  half  an  ounce  of  solution  of  ammonia,  and  dried, 
weighs  12.5  grains.’’ 

In  presence  of  chlorides  and  bromides  the  iodine  in 
iodides  may  be  precipitated  and  weighed  as  iodide  of 
palladium. 

BROMIDES. 

Free  bromine  may  be  estimated  by  shaking  with  excess 
of  solution  of  iodide  of  potassium,  and  then  determining 
the  equivalent  quantity  of  liberated  iodine  by  a standard 
solution  of  hyposulphite  of  sodium  (p.  493). 

The  bromine  inbromides  maybe  precipitated  and  weighed 
as  bromide  of  silver,  the  manipulations  being  the  same  as 
those  for  chloride  of  silver : 0.2  to  0.3  of  pure  bromide  of 
potassium  may  be  used  for  an  experimental  analysis. 

CYANIDES. 

The  hydrogen  cyanide  (h3'drocyanic  acid)  is  usually 
estimated  volumetrically  {ride  p.  48T). 

From  all  soluble  cyanides,  cyanogen  may  be  precipitated 
by  nitrate  of  silver,  after  acidulating  with  nitric  acid,  the 
cyanide  of  silver  collected  on  a tared  filter,  dried  at  100° 
C.,  and  weighed. 

Of  the  official  Diluted  Hydrocyanic  Acid,  it  is  stated 
that  one  hundred  grains  (or  110  minims)  precipitated  by 
solution  of  nitrate  of  silver  yield  ten  grains  of  dry  cyanide 
of  silver. 


Cyanide  of  Silver. 

Silver 

■ Ag  . 

In  1 molecule. 

. 107.93  . 

In  ICO  parts. 

. 80.59 

Cj^anogen 

. ON  . 

. 26.00  . 

. 19.41 

133.93 

100.00 

NITRATES. 

Nitrates  cannot  be  estimated  by  direct  gravimetric  ana- 
Ij^sis,  none  of  the  baysylous  radicals  yielding  a definite 
nitrate  insoluble  in  water.  With  some  difficulty  they  may 
be  determined  by  indirect  volumetric  methods. 


516 


QUANTITATIVE  ANALYSIS. 


Process. — The  best  method  is  that  by  Crum,  as  modified 
by  Frankland  and  Armstrong.  It  consists  in  agitating 
with  mercury  a concentrated  solution  of  the  nitrate  with  a 
large  excess  of  concentrated  sulphuric  acid — the  whole  of 
the  nitrogen  being  then  involved  as  nitric  oxide.  From  the 
volume  of  the  latter  the  weight  of  nitrate  wdience  obtained 
is  easily  calculated.  No  chlorides  must  be  present.  For 
educational  purposes  the  experiment  may  be  conducted  on 
3 or  4 c.  c.  of  a solution  of  one  gramme  of  pure  nitrate  of 
potassium  in  100  c.  c.  of  distilled  water.  From  1 to  10 
c.  c.  of  such  a solution  will  very  well  represent  the  nitrates 
in  half  a litre  of  well-water. 

The  following  is  the  mode  in  which  this  process  is  ap- 
plied to  the  estimation  of  nitrogen  existing  as  nitrates  and 


nitrites  in  potable  waters.  The  solid  residue  from 
half  a litre  of  water  used  for  determination  of  total 
solid  constituents*  is  treated  with  a small  quantity 
of  distilled  water,  a very  slight  excess  of  sulphate 
of  silver  is  added  to  convert  the  chlorides  present 
into  sulphates,  and  the  filtered  liquid  is  then  con- 
centrated by  evaporation  in  a small  beaker  until  it 
is  reduced  in  bulk  to  two  or  three  cubic  centime- 
tres. The  liquid  must  now  be  transferred  to  a glass 
tube  (about  as  long  as  the  hand)  (see  fig.)  pre- 
viously filled  with  mercury  at  the  mercurial  trough, 
and  furnished  at  its  upper  extremity  with  a cup 
and  stopcock,  the  beaker  being  rinsed  out  once  or 
twice  with  a very  small  volume  of  recently  boiled 
distilled  water,  and  finally  with  pure  and  concen- 
trated sulphuric  acid  in  somewhat  greater  volume 
than  that  of  the  concentrated  solution  and  rinsings. 
(For  a method  of  purifying  the  acid  vide  p.  276.) 
By  a little  dexterity  it  is  easy  to  introduce  suc- 
cessively the  concentrated  liquid,  rinsings,  and 
sulphuric  acid  by  means  of  the  cup  and  stopcock, 
without  the  admission  of  any  trace  of  air.  Should, 
however,  air  inadvertently  gain  admittance,  it  is 


* If  the  water  contains  nitrites,  a separate  half  litre  should  be 
taken  for  this  determination,  otherwise  there  is  a risk  of  loss  of  nitro- 
gen during  evaporation.  The  nitrites  in  this  half  litre  of  water  must 
be  transformed  into  nitrates  by  the  cautious  addition  of  potassic 
permanganate  to  the  slightly  acidified  water  before  the  evaporation 
is  commenced.  Immediately  after  the  action  of  the  permanganate 
the  water  must  be  again  rendered  slightly  alkaline. 


SULPHIDES. 


517 


readily  removed  by  depressing  the  tube  in  the  mercury 
trough,  and  then  momentarily  opening  the  stopcock.  If 
this  be  done  within  a minute  or  two  after  the  introduction 
of  the  sulphuric  acid,  no  fear  need  be  entertained  of  the 
loss  of  nitric  oxide,  as  the  evolution  of  this  gas  does  not 
begin  until  a minute  or  so  after  the  violent  agitation  of  the 
contents  of  the  tube. 

The  acid  mixture  being  thus  introduced,  the  lower  ex- 
tremity of  the  tube  is  to  be  firml3^  closed  by  the  thumb,  and 
the  contents  violently  agitated  b}^  a simultaneous  vertical 
and  lateral  movement,  in  such  a manner  that  there  is  always 
an  unbroken  column  of  mercuiy,  at  least  an  inch  long,  at 
the  bottom  part  of  the  glass  tube.  From  the  description, 
this  manipulation  ma}^  appear  difficult ; but  in  practice  it 
is  extremely"  simple,  the  acid  liquid  never  coming  in  contact 
with  the  flesh.  In  about  a minute  from  the  commencement 
of  the  agitation  a strong  pressure  begins  to  be  felt  against 
the  thumb  of  the  operator,  and  mereuiy  spurts  out  in  mi- 
nute streams,  as  nitric  oxide  gas  is  evolved.  The  escape 
of  the  metal  should  be  gently"  resisted,  so  as  to  maintain 
a considerable  excess  of  pressure  inside  the  tube,  and  thus 
prevent  the  possibility  of  air  gaining  access  to  the  interior 
during  the  shaking.  In  from  three  to  five  minutes  the 
reaction  is  completed,  and  the  nitric  oxide  ma^"  then  be 
transferred  to  a suitable  measuring-apparatus,  where  its 
volume  is  to  be  determined  over  mercury.  As  half  a litre 
of  water  is  used  for  the  determination,  and  as  nitric  oxide 
occupies  exactlj"  double  the  volume  of  the  nitrogen  which 
it  contains^  the  volume  of  nitric  oxide  read  off  expresses 
the  volume  of  .nitrogen  existing  as  nitrates  and  nitrites  in 
one  litre  of  the  water.  From  the  number  so  obtained,  the 
weight  of  nitrogen  in  these  forms  in  100,000  parts  of  water 
is  easil}^  calculated.  (1  litre  of  H weighs  .0896,  and  N.  is 
14  times  as  heaAy  as  H : 101  of  KNO3  contains  14  of  N.) 

SULPHIDES. 

Process  1. — Soluble  sulphides  (H.,S,  NaHS,  e.g,)  ma}^  be 
determined  volumetrically  by  adding  to  the  aqueous  liquid 
a measured  excess  of  an  alkaline  solution  of  arsenic  of 
known  strength,  neutralizing  by  hydrochloric  acid,  diluting 
to  an\"  given  volume,  filtering  off  the  sulphide  of  arsenicum 
precipitated,  taking  a portion  of  the  filtrate  equal  to  half 
or  a third  of  the  original  volume,  and,  after  neutralizing 
by  acid  carbonate  of  sodium,  estimating  the  residual  arse- 
44 


518 


QUANTITATIVE  ANALYSIS. 


iiic  by  the  standard  iodine  solution  {vide  p.  488).  The 
process  may  be  tried  on  a measured  volume  of  sulphuretted 
hydrogen  (the  weight  of  which  is  easily  calculated ; 1 litre  ' 
of  hydrogen  = 0.0896  gramme)  absorbed  by  a strong  solu- 
tion of  soda  or  potash. 

Process  2. — Sulphur  and  sulphides  may  also  be  quanti- 
tativel}^  analyzed  by  oxidizing  to  sulphuric  acid  and  pre- 
cipitating in  the  form  of  sulphate  of  barium.  A couple  of 
decigrammes  of  a pure  metallic  sulphide  may  be  decom- 
posed by  careful  deflagration  with  a mixture  of  chlorate  i 
of  potassium  and  carbonate  of  sodium,  the  product  dis-  i 
solved  in  water,  acidulated  with  hydrochloric  acid,  solution 
of  chloride  of  barium  added,  and  the  precipitated  sulphate 
of  barium  purified  and  collected  as  described  in  connection 
wdth  the  estimation  of  barium  (p.  502).  Many  sulphides 
may  be  oxidized  in  a flask  by  chlorate  of  potassium  and 
hj^drochloric  acid,  and  then  precipitated  by  chloride  of 
barium.  Experimental  determinations  may  also  be  made 
on  a weighed  fragment  of  sulphur,  about  0.1,  cautiously 
fused  with  a solid  caustic  alkali,  and  the  product  oxidized 
while  hot  by  the  slow  addition  of  powdered  nitrate  or 
chlorate  of  ])otassium,  or,  when  cold,  b}"  treatment  with 
chlorate  of  potassium  and  hydrochloric  acid,  and  subse- 
quent precipitation  by  chloride  of  barium. 

Note. — Fusions  performed  by  help  of  a gas-lamp  must  be  care- 
fully conducted;  for  any  alkali  that  may  creep  over  the  side  of  a 
crucible  will  certainly  absorb  sulphurous  acid  from  the  products  of 
combustion  of  the  gas,  and  error  result. 

Process  3. — Soluble  sulphides  may"  also  be  treated  with 
excess  of  an  alkaline  arseniate,  arsenious  sulphide  be  then 
precipitated  by  the  addition  of  hy^drochloric  acid,  and  the 
precipitate  collected  and  weighed  with  the  usual  precau- 
tions {cide  p,  508). 


Weights  of  equivalent  quantities  of  sulphur  and  its 
compounds. 


Sulphur 

. s 

. 32 

Sulphuretted  hydrogen  . 

. II, s .... 

. 34 

Sulphate  of  barium  . . . 

. BaSO,  . . . 

. 233 

Arsenious  sulphide  . . . 

. (As,S3)-^3  . . 

. 82 

Ilisulphide  of  iron  . . . 

(FeS,)-r-2  . . 

. GO 

Sulphide  of  lead  . . . . 

PbS  .... 

. 239 

SULPHITES  — SULPHATES  — CARBONATES.  519 


SULPHITES. 

Sulphites  are  usually  estimated  volumetrically  by  a 
standard  solution  of  iodine  {mde  p.  488).  Sulphites  insolu- 
ble in  water  are  diffused  in  that  menstruum,  hydrochloric 
acid  added,  and  the  iodine  solution  then  dropped  in. 

If  necessary,  sulphites  may  be  estimated  gravimetri- 
eally  by  oxidation  and  precipitation  in  the  form  of  sulphate 
of  barium. 


SULPHATES. 

These  salts  are  always  precipitated  and  weighed  as  sul- 
phate of  barium,  the  manipulations  being  identical  with 
those  performed  in  the  determination  of  barium  by  means 
of  sulphates  {mde  p.  502).  The  purity  of  Sulphate  of 
Sodium  (Sodae  Sulphas^  B.  P.),  and  the  presence  of  not 
more  than  a given  amount  of  sulphuric  acid  in  Vinegar 
{Acetum^  B.  P.),  are  directed,  in  the  British  Pharmacopoeia, 
to  be  ascertained  by  this  process.  Ten  grains  of  sulphate 
of  sodium  yield  7.236  of  sulphate  of  barium.  Five  ounces 
of  vinegar  should  yield  not  more  than  about  one-third  of  a 
gramme  of  sulphate  of  barium. 

Proportional  weights  of  equivalent  quantities  of  sulphates. 

The  sulphuric  radical  . . . SO^ 96 

Sulphuric  acid H^SO^  ....  98 

Sulphate  of  barium  ....  BaSO^ ....  233 

CAHBONATES. 

Carbonates  are  usually  estimated  by  the  loss  in  weight 
they  undergo  on  the  addition  of  a strong  acid. 

Process  1. — A small  light  flask  is  selected — of  such  a 
size  that  it  can  be  conveniently  weighed  in  a delicate 
balance.  Two  narrow  glass  tubes  are  fitted  to  the  flask  by 
a cork ; the  one  straight,  extending  from  about  two  or 
three  centimetres  above  the  cork  to  the  bottom  of  the  flask  ; 
the  other  cut  off  close  to  the  cork  on  the  inside  and  curved 
outwards  so  as  to  carry  a thin  drying-tube  horizontally 
above  the  flask.  The  diying-tube  may  be  a short  narrow 
test-tube,  the  bottom  of  which  is  constricted  so  as  to  form 
a narrow  tube  open  at  the  end  ; it  is  nearly  filled  with 
small  pieces  of  chloride  of  calcium,  a plug  of  cotton-wool 
preventing  escape  of  any  fragments  at  either  end,  and  is 
attached  by  a pierced  cork  to  the  free  extremity  of  the 
curved  tube  of  the  flask.  A weighed  quantity  of  an3^  pure 


520 


QUANTITATIVE  ANALYSIS. 


soluble  carbonate  is  placed  in  the  flask,  a little  water 
added,  a miniature  test-tube  containing  sulphuric  acid 
lowered  into  the  flask  by  a thread  and  supported  so  that 
the  acid  may  not  flow  out^  the  cork  inserted,  the  outer  end 
of  the  piece  of  the  straight  glass  tubing  closed  by  a frag- 
ment of  cork  or  wax,  and  the  whole  weighed.  The  appa- 
ratus is  then  inclined  so  that  the  oil  of  vitriol  and  carbon- 
ate may  slowly  react ; carbonic  acid  gas  is  evolved  and 
escapes  through  the  horizontal  tube,  any  moisture  being 
retained  by  the  chloride  of  calcium.  When  effervescence 
has  ceased,  the  gas  still  remaining  in  the  vessel  is  sucked 
out;  this  is  accomplished  by  adapting  a piece  of  India- 
rubber  tubing  to  the  end  of  the  drying-tube,  removing 
the  small  plug  from  the  straight  tube,  and  aspirating 
slowly  with  the  mouth  for  a few  minutes.  If  the  heat  pro- 
duced by  the  action  of  the  oil  of  vitriol  and  solution  is 
considered  insufficient  to  expel  all  the  carbonic  acid  from 
the  liquid,  the  plug  is  again  inserted  in  the  tube  and  the  con- 
tents of  the  flask  gently  boiled  for  some  seconds.  When 
the  apparatus  is  cold,  more  air  is  again  drawn  through  it, 
and  the  whole  finally  weighed.  The  loss  is  due  to  carbonic 
acid  gas  (CO2),  from  the  weight  of  which  that  of  any  car- 
bonate is  ascertained  by  calculation.  Carbonates  insoluble 
in  water  may  be  attacked  by  hj^drochloric  instead  of  sul- 
phuric acid;  granulated  mixtures  of  carbonates  and  pow- 
dered tartaric  or  citric  acids  by  inclosing  the  preparation 
in  the  inner  tube  and  placing  water  in  the  flask,  or  vice 
versa.  The  apparatus  also  may  be  modified  in  many  ways 
to  suit  the  requirements,  convenience,  or  taste  of  the  ope- 
rator. \ 

Process  2. — Carbonates  from  which  carbonic  acid  gas  is 
evolved  by  heat  may  be  estimated  by  the  loss  they  expe- 
rience on  ignition. 

Process  3. — Free  carbonic  acid  gas  may  be  absorbed  by 
a solid  stick  of  potash  or  a strong  alkaline  solution,  the 
loss  in  volume  of  the  gas  or  mixture  of  gases  indicating 
the  amount  originally  present.  ; 

Weights  of  eguivalent  quantities  of  carhonic  acid  gas  and  } 

certain  carbonates.  j 

Carbonic  acid  gas CO.^  . . . 44  | 

Carbonic  acid H^CO,  . . 62  ji 

Anh^ulrous  carbonate  of  sodium  . . Na^COy  . . 106  fi 

Anhydrous  carbonate  of  potassium  . . . 138 

Carbonate  of  calcium CaCOa  . . 100  ji 


OXALATES PHOSPHATES. 


521 


OXALATES. 

Process  1. — The  oxalic  radical  is  usually  precipitated  in 
the  form  of  oxalate  of  calcium,  and  weighed  as  carbonate, 
the  manipulations  being  identical  with  those  observed  in 
the  estimation  of  calcium  {vide  p.  504).  The  experiment 
may  be  performed  on  0.3  or  0.4  of  pure  crystallized  oxalic 
acid,  126  parts  of  which  should  yield  100  of  carbonate  of 
calcium. 

Process  2. — Oxalates  may  also  be  determined  byconver- 
sion of  their  acidulous  radical  into  carbonic  acid  gas,  and 
observation  of  the  weight  of  the  latter.  The  oxalate, 
water,  and  excess  of  black  oxide  of  manganese  are  placed 
in  the  carbonic  acid  apparatus,  a tube  full  of  oil  of  vitriol 
lowered  into  the  flask,  the  whole  weighed,  and  the  opera- 
tion completed  as  for  carbonates.  From  the  following 
equation  it  will  be  seen  that  every  88  parts  of  carbonic 
acid  gas  evolved  indicate  the  presence  of  126  parts  of 
crystallized  oxalic  acid  or  an  equivalent  quantity  of  other 
oxalate : — 

+ MnO.,  + 2H,SO,  = MnSO,  + JSFa.SO,  -f  2H,0 

+ 2CO^. 

The  black  oxide  of  manganese  used  in  this  experiment 
must  be  free  from  carbonates.  The  amount  of  materials 
employed  is  regulated  by  the  size  of  the  vessels. 

PHOSPHATES. 

Process  1. — From  phosphates  dissolved  in  water ^ the 
phosphoric  radical  may  be  precipitated  and  weighed  in  the 
form  of  pyrophosphate  of  magnesium,  the  details  of  ma- 
nipulation being  similar  to  those  observed  in  estimating 
magnesium  {vide  p.  505).  Half  a gramme  or  rather  more 
of  pure  dry  crystallized  phosphate  of  sodium  may  be 
emplo^'ed  in  experimental  determinations.  The  official 
phosphate  of  ammonium  {Ammonise  Phosphas^  B.  P.)  is 
quantitatively  analyzed  by  this  method.  If  twenty 
grains  of  this  salt  be  dissolved  in  water,  and  solution  of 
ammonio-sulphate  of  magnesia  added,  a crystalline  pre- 
cipitate falls,  which,  when  well  washed  upon  a filter  with 
solution  of  ammonia  diluted  with  an  equal  volume  of 
water,  dried,  and  heated  to  redness,  leaves  16.8  grains.’’ 
Half  a gramme  or  less  is  a more  convenient  quantity,  if 
the  operations  be  conducted  with  care.  Solution  of  am- 

44* 


522 


QUANTITATIVE  ANALYSIS. 


monio-sulpliate  of  magnesium  (B.  P.)  is  prepared  by  dis- 
solving 2 parts  of  sulphate  of  magnesium,  1 of  chloride 
of  ammonium,  and  1 of  solution  of  ammonia  (20.6  per  cent. 
KH^HO)  in  18  or  20  of  distilled  water ; such  a solution  is 
of  considerable  use  if  several  phosphoric  determinations 
are  about  to  be  made. 

Process  2. — Free  phosphoric  acid  is  most  readily  deter- 
mined as  phosphate  of  lead  (Pb32POJ.  Of  the  official 
solution  of  phosphoric  acid  it  is  stated  that  355  grains 
by  weight  poured  upon  180  grains  of  oxide  of  lead  in  fine 
powder  leave,  by  evaporation,  a residue  (principally  phos- 
phate of  lead)  which,  after  it  has  been  heated  to  dull  red- 
ness, weighs  215.5  grains.”  One-tenth  of  these  quantities 
may  be  used  for  experimental  purposes;  one  to  two  grammes 
will  give  good  results.  The  oxide  of  lead  must  be  quite 
pure  ; it  should  be  prepared  by  digesting  red  lead  in  warm 
dilute  nitric  acid,  washing,  drying,  and  heating  the  result- 
ing puce-colored  plumbic  oxide  in  a covered  porcelain 
crucible.  The  increase  in  weight  obtained  on  evaporating 
a given  amount  of  solution  of  phosphoric  acid  with  a 
known  weight  of  perfectly  pure  oxide  of  lead  (PbO)  may 
be  regarded  as  entirely  due  to  phosphoric  anh^^dride 

(PA), 

3PbO  + P,0,  = Pb,2PO„ 
the  actual  reaction  being. 


3PbO  + 2H3PO,  = Pb32PO,  -f  3H,0. 


From  these  equations,  and  the  table  of  atomic  weights 
{vide  Appendix),  the  percentage  of  phosphoric  acid 
(H3PO4)  in  any  specimen  of  its  solution  may  be  easily 
calculated. 

Process  3. — The  strength  of  pure  solution  of  phosphor'ic 
acid  may  be  ascertained  by  specific  gravity  and  reference 
to  Tables. 

Process  4. — Bone-earth,  “ superphospate,”  the  Calcis 
Phosphas  of  pharmacy,  and  other  forms  of  phosphate  of 
calcium  known  to  be  tolerably  free  from  iron  or  alumi- 
nium, may  be  estimated  by  treating  about  half  a gramme 
with  hydrochloric  acid  somewhat  diluted,  filtering  if 
necessary,  warming,  precipitating  with  excess  of  ammonia, 
collecting  the  precipitate  (Ca.j2POJ  washing,  drying,  igni-* 
ting,  and  weighing.  ‘‘  Calcis  phosphas  f if  pure,  wdll,  in 
this  process,  lose  no  weight. 

Process  5. — Insoluble  phosphates  in  ashes,  manures,  etc.. 


i 


QUESTIONS  AND  EXERCISES, 


523 


are  treated  as  follows  : a weighed  quantity  of  the  material 
(1.0  to  10.0)  is  digested  in  hydrochloric  acid  diluted  with 
three  or  four  times  its  bulk  of  water ; filtered  (insoluble 
matter  and  filter  being  thoroughly  exhausted  by  water)  ; 
ammonia  added  to  the  filtrate  and  washings  until,  after 
stirring,  a faint  cloudy  precipitate  is  perceptible  ; solution 
of  oxalic  acid  dropped  in  until,  after  agitation  for  a few 
minutes,  the  opalescence  is  removed  ; oxalate  of  ammonium 
next  added,  the  whole  warmed,  oxalate  of  calcium  removed 
by  filtration,  and  the  filtrate  concentrated  if  very  dilute  ; 
the  liquid  treated  with  citric  acid  in  such  quantity  that 
ammonia  when  added  in  excess  gives  a clear  lemon-yellow 
solution  (Warington),  magnesian  mixture  poured  in  (as  in 
Process  1),  and  the  precipitate  of  ammonio-magnesian 
phosphate  collected,  washed,  dried,  and  weighed  as  already 
described  in  connection  with  the  estimation  of  magnesium. 

Relative  weights  of  equivalent  quantities  of  phosphoiHc 
compounds. 

Phosphoric  acid H3PO^ 98 

Pyrophosphate  of  magnesium  (Mg3P.^O^  = 222)-i-2=  111 

Phosphate  of  lead  ....  (Pb32PO^  = 811) -^2=  405.5 
Phosphoric  anhydride  . . . (P205=142)  —2=  H 

Phosphate  of  calcium  . . . (Caj2PO^=310)  ~ 2=  155 

Superphosphate  of  calcium  (CaH^2PO^=234) -r- 2=  lit 


QUESTIONS  AND  EXERCISES. 

1044.  What  quantity  of  pure  rock-salt  is  equivalent  to  4.2  parts 
of  chloride  of  silver? — Ans.  1.712. 

1045.  State  the  percentage  of  real  iodide  of  potassium  contained 
in  a sample  of  which  8 parts  yield  10.9  of  iodide  of  silver. — Ayis. 
96.25. 

1046.  What  is  the  strength  of  a solution  of  hydrocyanic  acid  10 
parts  of  which,  by  weight,  yield  .9  of  cyanide  of  silver  ? — Ans.  1.81 
per  cent. 

1047.  How  are  nitrates  quantitatively  estimated  ? 

1048.  By  what  processes  may  the  strength  of  sulphides  be  deter- 
mined ? 

. 1049.  How  much  real  sulphate  of  sodium  is  contained  in  a speci- 
men 10  parts  of  which  yield  14.2  of  sulphate  of  barium  ? — Ans. 
86.34  per  cent. 

1050.  Give  details  of  the  operations  performed  in  the  quantitative 
analysis  of  carbonates. 


524 


QUANTITATIVE  ANALYSIS. 


1051.  What  amount  of  carbonic  acid  gas  should  be  obtained  from 
10  parts  of  acid  carbonate  (or  bicarbonate)  of  potassium  ? — Ans.  4.4 
parts. 

1052.  To  what  operation  and  what  quantities  of  materials  does 
the  following  equation  refer  ? 

Na,OA  + MnO,+  2H,SO,=  MnSO,+  Na^SO,  + 2H,0  + 2CO,. 

1053.  Explain  the  lead  process  for  the  estimation  of  phosphoric 
acid  in  the  official  solution. 

1054.  State  the  amount  of  superphosphate  of  calcium  equivalent 
to  7.6  parts  of  pyrophosphate  of  magnesium. — Ans.  8.01  parts. 


SILICATES.  j 

Silica  (SiOg)  may  be  separated  from  alkaline  silicates,  or  j 
from  silicates  decomposable  by  hydrochloric  acid,  by  digest-  i 
ing  the  substance  in  hydrochloric  acid  at  a temperature  of  | 
70^  or  80°  C.,  until  completely  disintegrated,  evaporating 
to  dryness,  heating  in  an  air-bath,  again  moistening  with 
acid,  diluting  with  hot  water,  filtering,  washing,  drying, 
igniting,  and  weighing. 

ESTIMATION  OF  WATER. 

W^ater,  being  readily  volatilized,  is  most  usually  estimated 
by  the  loss  in  w^eight  which  a substance  undergoes  on  being 
heated  to  a proper  temperature.  Thus,  in  the  British 
Pharmacopoeia,  crystalline  gallic  acid  (HgC^HgO.,  H^O)  is 
stated  to  lose  9.5  per  cent,  of  its  weight  at  a temperature 
of  100°  C.,  oxalate  of  cerium  (CeC.^O^,  BH^O)  52  per  cent, 
on  incineration,  carbonate  of  potassium  about  16  per  cent, 
on  exposure  to  a red  heat,  sulphate  of  quinine  (2C2oH,,_jN,,02, 
IT^SO^,  7H.^O)  14.4  per  cent,  at  100°  C.,  arseniate  of  sodium 
(Na.^HAsO^,  iH20)  40.38  per  cent,  at  149°  C.,  carbonate  of 
sodium  (Na^COg,  lOH^O)  63  per  cent.,  phosphate  of  sodium 
(Na2HPO^,  I2H2O)  63  per  cent.,  and  sulphate  of  sodium 
(Na.^SO^,  IOH2O)  55.9  per  cent,  at  a low  red  heat. 

Process. — One  or  two  grammes  of  substance  is  sufficient 
in  experiments  on  desiccation,  the  material  being  placed  in 
a watch-glass,  covered  or  uncovered  porcelain  crucible,  or 
other  vessel,  according  to  the  temperature  to  which  it  is  to 
be  exposed.  Rapid  desiccation  at  an  exact  temperature 
may  be  effected  by  introducing  the  substance  into  a tube’ 
liaving  somewhat  the  shape  of  the  letter  U,  sinking  the 
lower  part  of  the  tube  into  a liquid  kept  at  a definite  tem- 
perature by  aid  of  a tliermoineter,  and  drawing  or  forcing 


CARBON,  HYDROGEN,  OXYGEN,  NITROGEN.  525 

a current  of  dry  air  slowly  through  the  apparatus.  Sub- 
stances liable  to  oxidation  may  be  desiccated  in  a current 
of  dried  carbonic  acid  gas.  The  weights  of  the  U-tube 
before  and  after  the  introduction  of  the  salt,  and  after 
desiccation,  give  the  amount  of  water  souglit.  In  all  cases 
the  material  must  be  heated  until  it  ceases  to  lose  weight. 
Occasionally  it  is  desirable  to  estimate  water  directly  by 
conveying  its  vapor  in  a current  of  air  through  a weighed 
tube  containing  chloride  of  calcium  and  re-weighing  the 
tube  at  the  close  of  the  operation ; the  increase  shows  the 
amount  of  water. 

Note. — Highly  dried  substances  rapidly  absorb  moisture  from  the 
air  ; they  must  therefore  be  weighed  quickly,  inclosed,  if  possible,  in 
tubes  (p.  498),  a pair  of  clamped  watch-glasses,  or  a crucible  having 
a tightly  fitting  lid. 

CARBON.  HYDROGEN,  OXYGEN,  NITROGEN. 

The  quantitative  analysis  of  animal  and  vegetable  substances  is 
either  pi'oximate  or  ultimate.  Proximate  analysis  includes  the 
estimation  of  water,  oil,  albumen,  starch,  cellulose,  gum,  resin,  alka- 
loids, acids,  glucosides,  ash.  It  requires  the  application  of  much 
theoretical  knowledge  and  manipulative  skill,  and  cannot  well  be 
studied  except  under  the  guidance  of  a tutor.  The  best  published 
work  on  the  subject  is  by  Rochleder,  a translation  of  whose  mono- 
graph will  be  found  in  the  Pharmaceutical  Journab  vol.  i.  2d  ser.  pp. 
562,  610  ; vol.  ii.  2d  ser.  pp.  24,  129, 160,  215,  274,  420,  478. 

Ultimate  orga^iic  analysis  can  only  be  successfully  accomplished 
with  the  appliances  of  a well-appointed  laboratory — a good  balance, 
a gas-furnace  giving  a smokeless  flame  (7  or  8 centimetres  wide  and 
70  or  80  centimetres  long),  special  forms  of  glass  apparatus,  etc. 
The  theory  of  the  operation  is  simple  : a weighed  quantity  of  a sub- 
stance is  burnt  to  carbonic  acid  gas  (002  = 44)  and  water  (H20=18), 
and  these  products  collected  and  weighed  ; 12  parts  in  every  44  of 
carbonic  acid  gas  (=/y)  are  carbon,  2 in  every  18  of  water  (=^) 
are  hydrogen  ; nitrogen  if  present  escapes  as  gas.  If  nitrogen  be  a 
constituent,  more  of  the  substance  is  strongly  heated  with  a mixture 
of  the  hydrates  of  sodium  and  calcium  ; these  bodies  then  split  up 
into  oxides,  oxygen,  and  hydrogen  ; the  oxygen  burns  the  carbon  of 
the  substance  to  carbonic  acid  gas,  its  hydrogen  and  nitrogen 
appearing  as  water  and  ammonia  respectively  ; the  carbonic  acid  and 
water  are  disregarded,  the  ammonia  collected  and  weighed  in  the 
form  of  a double  chloride  of  platinum  and  ammonium  (PtCb2NH^Cl 
=447),  of  which  28  parts  in  every  447  are  nitrogen.  The 

‘difference  between  the  sum  of  the  weights  of  hydrogen  and  carbon, 
and  the  weight  of  substance  taken,  is  the  proportion  of  oxygen  in  the 
body,  supposing  nitrogen  to  be  absent.  If  nitrogen  is  present,  the 
difference  between  the  sum  of  the  percentages  of  carbon,  hydrogen, 
and  nitrogen,  and  100,  is  the  percentage  of  oxygen.  Shortly,  carbon 


526 


QUANTITATIVE  ANALYSIS. 


is  estimated  in  the  form  of  carbonic  acid  gas,  hydrogen  as  water, 
nitrogen  as  ammonia,  and  oxygen  by  loss. 

The  folloiDingis  the  outline  of  the  necessary  manipulations. 
The  source  of  the  oxygen  for  the  combustion  of  carbon  and 
hydrogen  is  black  oxide  of  copper  in  coarse  powder.  200 
or  300  grammes  of  this  material  are  heated  in  a crucible  to 
low  redness  for  a short  time  to  expel  every  trace  of  mois- 
ture ; then  transferred  to  tubes  (store-tubes)  resembling 
test-tubes,  half  a metre  long,  and  having  a slightly  narrowed 
mouth,  the  tube  being  held  in  a cloth  to  protect  the  hand 
while  the  hot  oxide  is  being  directly  introduced  into  the 
mouth  of  the  tube  by  a scooping  motion.  As  soon  as  the 
well-corked  tube  is  cool,  the  oxide  is  poured,  portion  by 
portion,  into  a similar  tube  (the  combustion  tube),  some- 
what longer,  drawn  out  to  a quill  (bent  upwards  nearly  to 
a right-angle)  at  one  end,  not  constricted  at  the  mouth,  and 
containing  a few  decigrammes  of  fused  chlorate  of  potas- 
sium. After  ten  or  fifteen  centimetres  of  oxide  have  been 
l)Oured  in,  about  a decigramme  of  the  substance  to  be 
analyzed  is  dropped  down  the  tube,  then  a few  grammes 
of  oxide,  then  another  decigramme  of  substance,  then 
more  oxide,  until  three  or  four  decigrammes  of  the  body 
under  examination  have  been  added.  The  fifteen  or  twenty 
centimetres  of  alternate  layers  are  next  thoroughly  mixed 
by  a long  copper  wire  having  a short  helix,  more  oxide  is 
introduced,  the  wire  cleansed  by  twisting  the  helix  about 
in  the  pure  oxide,  and  a plug  of  asbestos  finally  placed  on 
the  top  of  the  oxide  at  about  five  centimetres  from  the 
mouth  of  the  tube;  the  tube  is  then  securely  corked  and 
set  aside.  The  substance  operated  on  may  be  pure  white 
sugar,  powdered  and  dried ; the  tube  in  which  it  is  contained 
is  weighed  before  and  after  the  removal  of  a portion  for 
combustion,  the  loss  is  the  quantity  employed  in  the  experi- 
ment. If  the  combustion-furnace  is  powerful,  or  the  com- 
bustion-tube not  of  the  hardest  glass,  the  tube  should  be 
inclosed  in  wire  gauze  the  elasticity  of  which  has  been 
destroyed  by  heating  to  redness.  In  the  combustion  of 
substances  containing  nitrogen,  the  plug  of  asbestos  must 
be  displaced  by  one  of  copper  turnings,  which  serve  to 
reduce  any  oxides  of  nitrogen,  and  thus  insure  the  escape 
of  nitrogen  itself.  The  water  produced  when  the  prepared 
tube  is  heated,  is  collected  in  a small  U-tube  containing 
pieces  of  chloride  of  calcium,  or  pumice-stone  moistened 
with  sulphuric  acid  ; the  carbonic  acid  gas  in  a series  of 


CARBON,  HYDROGEN,  OXYGEN,  NITROGEN.  521 

bulbs  containing  solution  of  potash  (sp.  gr.  about  1.2T). 
These  bulbs  may  be  purchased  at  any  apparatus-shop. 
The  chloricle-of-calcium  tube  is  fitted  by  a good  cork  to  the 
combustion-tube,  the  potash-bulbs  by  a short  piece  of  India- 
rubber  tubing  to  the  chloride-of-calcium  tube.  The  potash- 
bulbs  may  carry  a short  light  tube  containing  a rod  of 
caustic  potash  three  or  four  centimetres  long;  this  serves 
to  arrest  any  moisture  that  might  be  carried  away  from 
the  solution  of  potash  by  the  dried  expanded  air  which 
escapes  during  the  operation.  The  combustion-tube  having 
been  placed  in  the  furnace,  and  the  drying-tube  and  potash- 
bulbs  weighed  and  attached,  the  gas  is  lit  under  the  asbes- 
tos, and,  when  the  tube  is  red-hot,  the  flame  slowly  extended 
until  nearly  the  whole  tube  is  at  the  same  temperature,  the 
operation  being  conducted  at  such  a rate  that  bubbles  of 
gas  escape  through  the  bulbs  at  about  the  rate  of  one  per 
second.  When  no  more  gas  passes,  the  extremity  of  the 
tube  containing  the  chlorate  of  potassium  is  gently 
heated  until  ox3^gen  ceases  to  be  evolved;  the  quilled 
extremity  of  the  combustion-tube  is  then  broken,  and  air 
drawn  slowly  through  the  apparatus  by  suction  through 
an  India-rubber  tube  fixed  on  the  free  end  of  the  potash- 
bulbs,  perfect  combustion  of  carbon  and  removal  of  all 
carbonic  acid  gas  is  thus  insured.  The  drying-tube  and 
bulbs  are  disconnected  and  weighed  ; the  increase  in  weight 
due  to  carbonic  acid  gas  and  water  respectively  noted,  and 
the  percentages  of  carbon,  h^^drogen,  and  (by  loss)  oxygen 
calculated.  This  method  is  that  of  Liebig,  with  modifica- 
tions by  Bunsen  ; good  combustion-furnaces  are  those 
known  as  Hofmann’s  and  Griffin’s. 

The  general  mojiipulations  for  substances  containing 
nitrogen  resemble  the  foregoing  so  far  as  the  use  of  a com- 
bustion-tube and  furnace  and  collection  of  the  ammoniacal 
gas  are  concerned.  The  combustion-tube  must  be  quilled 
at  one  end,  and  about  a third  of  a metre  long.  The  soda- 
lime  is  made  by  slaking  quicklime  with  a solution  of  soda, 
of  such  a strength  that  about  two  parts  of  quicklime  shall 
be  mixed  with  one  of  hydrate  of  sodium,  drying  the  pro- 
duct, heating  to  bright  redness,  and  finely  powdering ; it 
should  be  preserved  in  a well-closed  bottle.  Some  of  the 
soda-lime  is  introduced  into  the  tube,  then  layers  of  sub- 
stance and  soda-lime,  mixture  effected  by  a wire,  more  soda- 
lime  added,  and  lastly  a plug  of  abestos.  Bulbs,  known 
as  those  of  Will  and  Yarrentrapp  (the  originators  of  the 
method),  containing  hydrochloric  acid  of  about  25  per  cent.. 


528 


QUANTITATIVE  ANALYSIS. 


are  then  fitted  by  a cork,  and  the  tube  Ideated  in  the  fur- 
nace. When  gas  ceases  to  pass,  the  quill  is  broken,  and 
aspiration  continued  slowly  until  ammoniacal  gas  may  be 
considered  to  have  been  all  removed.  The  bulbs  are  dis- 
connected, their  contents  and  rinsings  poured  into  a small 
dish,  solution  of  perchloride  of  platinum  added,  and  the 
operation  completed  as  in  the  estimation  of  ammonium  and 
potassium  salts  {vide  pages  502  and  499). 

Liquids  are  analyzed  by  a similar  method  to  that  adopted 
for  solids,  volatile  liquids  being  inclosed  in  small  bulbs 
having  a long  quill.  These  are  weighed  previously  to  and 
after  the  introduction  of  the  liquid;  just  before  being 
dropped  into  the  combustion  tube  the  quill  is  broken. 

Formulse, — From  the  percentage  composition  of  an  or- 
ganic substance  an  empirical  formula  may  be  deduced  by 
dividing  the  weight  of  each  constituent  by  its  atomic  weight,  j 
and  converting  the  product  into  the  simplest  whole  num- 
bers ; a rational  formula  by  ascertaining  the  proportion  in 
which  the  substance  unites  with  a radical  or  body  having 
a knoTvn  combining  proportion,  etc.  { vide  p.  873). 

Chlorine^  bromine^  or  iodine  contained  in  an  organic 
substance  is  usually  estimated  by  heating  to  redness  a 
given  weight  of  the  material  with  ten  times  as  much  pure 
lime  in  a combustion-tube.  Chloride,  bromide,  or  iodide 
of  calcium  is  thus  produced.  While  still  hot  the  tube  is 
plunged  into  water,  the  mixture  of  broken  glass  and  pow- 
der treated  with  pure  diluted  nitric  acid  in  slight 

excess;  the  filtered  liquid  precipitated  by  nitrate  of  sil- 
ver, and  the  chloride,  bromide,  or  iodide  of  silver  collected, 
washed,  dried,  and  weighed. 

Sulphur^  phosphorus^  and  arsenicum  in  organic  salts 
may  be  estimated  by  gradually  heating  in  a combustion- 
tube  1 part  of  the  substance  with  a mixture  of  10  parts 
nitre,  2 dried  carbonate  of  sodium,  and  30  chloride  of 
sodium  (in  order  to  moderate  deflagration).  The  product 
is  dissolved  in  water  acidulated  by  nitric  acid,  the  sulphu- 
ric radical  precipitated  and  estimated  as  sulphate  of  barium, 
the  phosphoric  and  arsenic  radicals  as  ammonio-magnesiaii 
phosphate  or  arseniate. 

QUINIA  OR  QUININE. 

A quantitative  determination  of  the  purity  of  commer- 
cial sulphate  of  quinia  may  be  made  b}’  De  Try’s  process. 

2 grammes  of  the  salt  are  dissolved  in  12  c.  c.  of  distilled 


QUINIA  OR  QUININE. 


529 


water  and  1.6  c.  c.  of  diluted  sulphuric  acid  (B.  P.).  8 c.  c. 
of  solution  of  hydrate  of  sodium  (1  to  12)  and  30  c.  c.  of 
pure  dry  ether  are  added,  the  whole  well  shaken  and  laid 
aside  for  twelve  hours.  The  ethereal  solution  decanted 
and  evaporated  gives  the  quinia.  The  aqueous  solution, 
carefully  neutralized  by  acetic  acid  and  strong  solution  of 
iodide  of  potassium  (1  in  4)  added,  gives  a white  precipi- 
tate of  hydriodate  of  quinidia,the  mother-liquor  containing 
any  cinchonia  and  cinchonidia  that  may  be  present.  The 
precipitate  is  collected  on  a tared  filter,  washed,  dried^  and 
weighed  ; it  contains  T1.68  per  cent,  of  pure  qiiinidia.  The 
filtrate  and  washings  are  rendered  alkaline  by  solution  of 
soda;  cinchonia  and  cinchonidia  are  precipitated,  and  ma}" 
be  collected,  washed,  dried,  and  weighed. 

Note, — If  the  quinia  in  drying  assumes  a resinoid  cha- 
racter it  should  be  redissolved  in  ether,  and  the  solution, 
when  concentrated,  allowed  to  evaporate  very  slowly  or 
spontaneously. 

Be  Vri/^s  method  for  the  separation  and  quantitative  de- 
termination of  all  the  different  cinchona  alkaloids.  This  is 
based  upon  the  following  facts  (nomenclature  after  De 
Vry) 

1.  The  great  solubility  of  quinine  and  amorphous  alka- 
loid in  ether,  and  the  relative  insolubility  of  qiiinidine,  cin- 
chonidine,  and  cinchonine  in  this  liquid. 

2.  The  great  solubility  of  the  iodo-sulphate  of  the  amor- 
phous alkaloid  in  alcohol,  and  the  very  small  solubility  of 
the  iodo-sulphate  of  quinine  (herapathite)  in  this  liquid. 

3.  The  great  difference  in  solubility  between  the  tartrate 
of  cinchonidine  and  the  tartrates  of  cinchonine  and  quini- 
dine — the  first  being  soluble  in  1265  parts  of  water  at  10^ 
C.,  the  second  in  35.6  parts  of  water  at  16^  C.,  and  the  third 
in  38.8  parts  of  water  at  15^  C. 

4.  The  great  difference  in  solubility  between  the  hydrio- 
date of  quinidine  and  the  hydriodates  of  cinchonidine  and 
cinchonine  in  water  and  alcohol. 

1 part  of  hydriodate  of  quinidine  requires  1250  parts  of 
water  at  15^  C.,  or  110  parts  of  alcohol. 

1 part  of  hj'driodate  of  cinchonidine  requires  110  parts 
of  water,  or  3 parts  of  alcohol. 

1 part  of  hydriodate  of  cinchonine  requires  128  parts  of 
water,  or  3 parts  of  alcohol. 

These  facts  are  applied  to  the  separation  and  determina- 
tion of  the  different  cinchona  alkaloids  in  the  following 
manner : — 

45 


530 


QUANTITATIVE  ANALYSIS. 


Five  to  ten  grammes  of  the  pulverized  mixed  alkaloids 
are  mixed  with  50  grammes  of  ether,  and  the  mixture,  after 
well  shaking,  left  at  rest  till  the  next  day.  By  this  opera- 
tion the  alkaloids  are  separated  into  two  parts,  viz.,  one 
(A)  soluble  in  ether,  and  another  (B)  insoluble  in  that 
liquid.  The  part  soluble  in  ether  contains  the  quinine  and 
the  amorphous  alkaloid,  together  with  traces  of  quinidine 
or  cinchonidine,  whilst  the  insoluble  part  contains  the  cin- 
chonidine,  cinchonine,  and  quinidine.  These  two  parts  are 
separated  by  a filter,  the  insoluble  part  washed  with  some 
ether,  and  the  ethereal  solution  either  evaporated  or  dis- 
tilled. 

A.  Part  soluble  in  Ether. — The  residue  left  by  the  evapo- 
ration of  the  ether  is  dissolved  in  10  parts  of  proof  spirit 
acidulated  by  one-twentieth  of  sulphuric  acid.  To  this  solu- 
tion is  carefully  added  an  alcoholic  solution  of  iodine  till  a 
precipitate  is  no  longer  formed.  This  part  of  the  process 
is  the  most  difficult,  and  requires  some  experience.  If  the 
mixed  alkaloids  contain  a large  amount  of  quinine,  there 
appears  immediatel}^  a black  precipitate  of  quinine-herapa- 
thite,  wdiereby  the  addition  of  the  solution  of  iodine  is  regu- 
lated ; but  if  the  amount  of  quinine  is  only  very  small,  it 
may  happen  that  the  precipitate  of  herapathite  does  not  ap- 
pear immediately.  In  such  a case  onl}"  a small  quantity 
of  iodine  must  be  added,  and  the  liquid,  after  having  been 
stirred  b}^  a glass  rod,  left  till  the  next  day.  If  quinine  is 
really  present,  it  will  then  be  precipitated  in  the  form  of 
herapathite.  The  chief  desideratum  of  tliis  part  of  the  pro- 
cess is  to  add  enough  and  not  too  much  iodine.  The  hera- 
pathite is  collected  upon  a filter,  washed  with  strong  alcohol, 
dried  upon  blotting-paper,  and  heated  in  a water-bath.  One 
part  of  the  herapathite,  thus  dried,  represents  0.565  part  of 
pure  quinine. 

The  liquid  separated  from  the  herapathite  is  mixed  with 
an  alcoholic  solution  of  sulphurous  acid,  whereby  the  iodo- 
sulphate  of  amorphous  alkaloid  is  converted  into  hydrio- 
date,  and  the  red-brown  color  disappears.  The  solution  is 
then  carefully  neutralized  by  caustic  soda,  and  heated  on 
a water-bath  to  expel  the  alcohol,  after  which  it  is  precipi-  | 
tated  by  a slight  excess  of  soda.  The  precipitate  consists  | 
of  the  amorphous  alkaloid,  containing  traces  of  quinidine  | 
or  cinchonidine,  if  these  alkaloids  were  contained  in  the  ( 
mixed  alkaloids. 

B.  Part  Insoluble  in  Ether. — This  part  is  mixed  with  40 
parts  of  hot  water,  and  converted  into  neutral  sulphate  by 


QUINTA  OR  QUININE. 


531 


careful  addition  of  diluted  sulphuric  acid,  so  that  a solution 
is  obtained  having  a slight  alkaline  reaction  upon  red  litmus 
paper.  To  this  solution  a solution  of  tartrate  of  potash 
and  soda  is  added  in  sufficient  quantity  to  convert  the  sul- 
phates into  tartrates,  and,  after  stirring  with  a glass  rod,  it 
is  left  till  the  next  day.  If  cinchonidine  be  present  in  ap- 
preciable quantity,  its  tartrate  will  be  found  separated  in 
crystalline  form,  whilst  the  other  tartrates  remain  dissolved ; 
if  only  traces  of  cinchonidine  be  present  striae  will  be  ob- 
served on  every  spot  of  the  glass  which  has  been  rubbed  by 
the  glass  rod.  The  tartrate  of  cinchonidine  is  collected 
upon  a filter,  washed  with  a little  water,  and  dried  on  a 
water-])atli.  One  part  of  this  tartrate  represents  0.804  part 
of  cinchonidine. 

The  liquor  separated  from  this  tartrate  is  mixed  witli  a 
solution  of  iodide  of  potassium,  and  well  stirred  by  a glass 
rod.  If  quinidine  is  present  in  appreciable  quantity,  a 
sandy  crystalline  powder  of  hydriodate  of  quinidine  will  be 
precipitated,  which  is  collected  upon  a filter,  washed  with 
a little  water,  and  dried  on  a water-bath.  One  part  of  this 
hydriodate  represents  0.718  part  of  anhydrous  quinidine. 
If  only  a trace  of  quinidine  be  present,  no  precipitate  will 
appear,  but  only  strim  on  every  spot  of  the  glass  which  has 
been  rubbed  by  the  glass  rod. 

The  liquor  separated  from  the  hydriodate  of  quinidine  is 
precipitated  by  caustic  soda,  whereby  the  cinchonine  is 
obtained.  It  is  collected  upon  a filter,  washed  with  water, 
and  dried  on  a water-bath. 

Dr.  de  Try  states  that  he  is  aware  that  this  process  is  far 
from  perfect.  For  instance,  the  tartrate  of  cinchonidine 
and  the  hydriodate  of  quinidine,  although  difficultly  soluble 
in  cold  water,  are  not  insoluble ; and  therefore  the  quanti- 
ties of  the  alkaloids  determined  by  this  process  are  too 
small,  whilst,  consequently,  that  of  the  cinchonine  found  is 
too  large.  The  best  part  of  the  process  is  the  accurate 
determination  of  the  real  quinine  contained  in  a bark,  and 
the  impossibility  of  overlooking  one  of  the  mentioned  five 
alkaloids  which  may  be  contained  in  a bark. 

Carles^s  Proces^i  for  the  Valuation  of  Cinch  on  a-harks. — 
An  average  sample  of  the  bark  is  reduced  to  fine  powder 
and  passed  through  a sieve  without  residue.  Twenty 
grammes  are  then  taken  and  intimately  mixed  in  a mortar 
with  8 grammes  of  slaked  lime  previously  mixed  with  35 
grammes  of  water.  This  mixture,  spread  on  a plate,  is  dried 
in  the  air  in  summer,  or  on  a water-bath  at  other  times. 


532 


QUANTITATIVE  ANALYSIS. 


When  all  the  moisture  has  evaporated,  the  lumps  are  broken 
up,  and  the  powder  packed  in  a percolator  with  a piece  of 
lint  at  the  bottom.  Chloroform  is  then  passed  tli rough  in  ' 
successive  portions  till  thp  mass  is  exhausted.  This  is 
ascertained  by  receiving  the  last  drops  in  a watch-glass, 
evaporating  to  dryness,  and  pouring  on  the  residue  water 
acidulated  with  sulphuric  acid,  then  solution  of  chlorine, 
and  lastly  ammonia.  When  a green  color  is  no  longer  pro- 
duced, it  is  known  that  all  the  quinine  has  been  removed. 
When  the  operation  is  well  conducted,  about  150  grammes 
of  chloroform  suffice  for  this  purpose.  The  menstruum  re- 
tained by  the  mass  is  displaced  by  water,  and  the  whole  of 
the  chloroform  solution  is  either  distilled  or  evaporated  to 
-dryness.  To  separate  the  alkaloids  from  the  residue,  it  is 
treated  several  times  in  the  cold  with  diluted  sulphuric  acid 
(1  to  10).  10  to  12  cubic  centimetres  are  sufficient.  This  i 

solution  thrown  upon  a moistened  filter  passes  through  color-  | 
less,  and  free  from  resinous  matter  ; it  is  raised  to  the  boil-  | 
ing-point,  and  ammonia  cautiously  added,  so  as  to  leave  I 
the  liquid  with  a slightly  acid  reaction.  The  sulphate  of  j 
ammonia  thus  formed  appears  to  prevent  the  mother-liquors 
from  retaining  sulphate  of  quinine  in  solution.  All  the 
quinine  crystallizes  out  in  the  state  of  sulphate.  After 
some  time  it  is  collected  on  a double  filter,  the  mother- 
liquors  displaced  b}^  a little  water,  and  the  crystals  dried 
and  weighed.  It  is  preferable  to  dry  completely  at  100°  I 
C.,  and  after  weighing  in  this  state  to  add  the  12  per  cent,  j 
of  water  which  is  lost  by  this  treatment.  The  other  alka-  j 
loids  retained  in  the  mother-liquors  are  separated  by  pre-  i 
cipitation.  | 

Of  the  Citrate  of  Iron  and  Quinia  (Fend  et  Quinise  j 
Citras^  B.  P.  and  U.  S.  P.)  it  is  officially  stated  that  ‘‘  fifty 
grains  dissolved  in  a fiuidounce  of  water  and  treated  wdth  j 
a slight  excess  of  ammonia  give  a white  precipitate  which,  | 
when  collected  on  a filter,  washed,  and  dried  (at  260  F.)  t 
weighs  eight  grains.  The  precipitate  is  almost  entirelj''  ' 
soluble  in  two  or  three  fluidrachms  of  pure  ether,’’  and  the 
ethereal  solution  set  aside  for  twelve  hours  in  a small  well- 
corked  bottle  yields  no  crystalline  deposit  (of  quinidia). 

MORPHIA. 

The  official  process  for  the  estimation  of  this  alkaloid  in 
opium  is  conducted  in  the  following  manner: — 

Take  of  opium  100  grains,  slaked  lime  100  grains,  dis- 


MORPHIA. 


533 


tilled  water  4 ounces.  Break  down  the  opium,  and  steep 
it  in  an  ounce  of  the  water  for  twenty-four  hours,  stirring 
the  mixture  frequently.  Transfer  it  to  a displacement- 
apparatus,  and  pour  on  the  remainder  of  the  water  in  suc- 
cessive portions,  so  as  to  exhaust  the  opium  by  percolation. 
To  the  infusion  thus  obtained,  placed  in  a flask,  add  the 
lime,  boil  for  ten  minutes,  place  the  undissolved  matter  on 
a filter,  and  wash  it  with  an  ounce  of  boiling  water.  Acid- 
ulate the  Altered  fluid  slightly  with  diluted  hydrochloric 
acid,  evaporate  it  to  the  bulk  of  half  an  ounce,  and  let  it 
cool.  Neutralize  cautiously  with  solution  of  ammonia, 
carefully  avoiding  an  excess ; remove  by  filtration  the 
brown  matter  which  separates,  wash  it  with  an  ounce  of 
hot  water,  mix  the  washings  with  the  filtrate,  concentrate 
the  whole  to  the  bulk  of  half  an  ounce,  and  add  now  solu- 
tion of  ammonia  in  slight  excess.  After  twenty-four  hours 
collect  the  precipitated  morjfliia  on  a weighed  filter,  wash 
it  with  cold  water,  and  dry  it  at  212°  F.  It  ought  to  weigh 
at  least  from  six  to  eight  grains. 

Of  Hydrochlorate  of  Morphia  it  is  stated  that  “ twenty 
grains  of  the  salt  dissolved  in  half  an  ounce  of  warm  water, 
with  ammonia  added  in  the  slightest  possible  excess,  give 
on  cooling  a crystalline  precipitate  which,  when  washed 
with  a little  cold  water  and  dried  by  exposure  to  the  air, 
weighs  15.18  grains.’^ 

Testing  Opium, — Professor  Schneider  has  proposed,  in 
the  6th  revised  edition  of  the  Pharmacopoeia  Austriaca, 
the  following  method  for  testing  the  quality  of  opium. 
Ten  grammes  of  previously  dried  and  powdered  opium  are 
treated  with  a mixture  of  150  grammes  of  distilled  water, 
to  which  20  grammes  of  pure  hydrochloric  acid,  sp.  gr.  1.12, 
are  added  ; the  residue,  after  extraction,  should  not  exceed 
4.5  grammes  w^eight ; to  tlie  acid  fluid  20  grammes  of  com- 
mon salt  are  added,  and  the  precipitate  thereby  caused  is 
collected,  after  tw'enty-four  hours,  on  a filter,  and  the  lat- 
ter washed  with  a solution  of  common  salt;  to  the  filtrate 
ammonia  is  added,  and  the.  fluid  left  standing  again  for 
twentj’-four  hours ; the  crj^stals  which  have  separated  are 
collected,  redissolvQd  in  acetic  acid,  and  precipitated  with 
ammonia;  the  precipitate  so  obtained  is  washed,  dried,  and 
weighed;  its  weight  should  not  be  less  than  1 gramme. 


45* 


534 


QUANTITATIVE  ANALYSIS. 


SUGAR. 

The  qualitative  test  of  sugar,  hy  means  of  an  alkaline 
copper  solution  (vide  p.  347),  may  be  applied  in  the  esti- 
mation of  sugar  in  sacchariferous  substances. 

Process, — 34.64  grammes  of  pure  dry  crystals  of  ordi- 
nary sulphate  of  copper  are  dissolved  in  about  250  c.  c.  of 
distilled  water,  173  grammes  of  pure  crystals  of  the  double 
tartrate  of  potassium  and  sodium  are  dissolved  in  480  c.  c. 
of  solution  of  caustic  soda  of  sp.  gr.  1.14.  The  solutions 
are  mixed  and  water  added  to  one  litre.  100  c.  c.  of  this 
solution  represent  3.464  grammes  of  sulphate  of  copper, 
and  correspond  to  0.5  of  a gramme  of  pure  anhydrous 
grape-sugar,  0.475  of  cane-sugar,  or  0.45  of  starch.  It  must 
be  preserved  in  a well-stoppered  bottle  to  prevent  absorp- 
tion of  carbonic  acid,  and  be  kept  in  a dark  place.  If  it 
give  a precipitate  on  boiling,  a little  solution  of  soda  may 
be  added  in  making  experiments. 

Dissolve  0.475  of  pure  dry  powdered  cane-sugar  in  about 
50  c.  c.  of  water,  convert  into  grape-sugar  by  acidulating 
with  sulphuric  acid,  and  boiling  for  an  hour  or  two,  neu- 
tralize with  carbonate  of  sodium,  and  dilute  to  100  c.  c. 
Place  10  c.  c.  of  the  copper  solution  in  a small  flask,  dilute 
with  three  or  four  times  its  bulk  of  water,  and  gently  boil. 
Into  the  boiling  liquid  drop  the  solution  of  sugar  from  a | 
burette,  one  cubic  centimetre,  or  less,  at  a time,  until,  after 
standing  for  the  precipitate  to  subside,  the  supernatant 
liquid  has  just  lost  its  blue  color;  10  c.  c.  of  the  solution 
of  the  sugar  should  be  required  to  produce  this  effect, 

= 0.475  of  cane-sugar  or  0.5  of  grape-sugar.  Experiments 
on  pure  cane-sugar  must  be  practised  until  accuracy  is  at- 
tained; syrups,  diabetic  urine,  and  saccliarated  substances 
containing  unknown  quantities  of  sugar  may  then  be  ana- 
l3^zed. 

Starch  is  converted  into  grape-sugar  by  gentle  ebullition 
with  dilute  acid  for  eight  or  ten  hours,  the  solution  being 
finall}^  diluted  so  that  one  part  of  starch,  or  rather  sugar,  ! 
shall  be  contained  in  about  150  of  water.  ! 

Saccharimetry . — A generic  term  for  certain  volumetric  i 
operations  undertaken  with  the  view  of  ascertaining  the  j 
quantity  of  sugar  present  in  any  matter  in  which  it  may  j 
be  contained.  j 

Sacchariinetiy  is  frequently  performed  upon  common  j 
syrup  (Syrupiis,^  B.  P.)  and  solutions  which  are  known  to  ! 


SUGAR. 


535 


contain  nothing  but  cane-  (ordinary)  sugar,  the  object  being 
merely  to  ascertain  the  amount  present.  In  such  a case 
it  is  only  necessary  to  take  the  specific  gravity  of  the  liquid 
at  60°  F.,  and  then  refer  to  a previously  prepared  Table  of 
densities  and  percentages. 


Specific 

Sugar 

Specific 

gravity. 

per  cent. 

gravity. 

1.007  . 

. 1.8 

1.100 

1.014  . 

. 3.5 

1.108 

1.022  . 

. 5.2 

1.116 

1.029  . 

. 7.0 

1.125 

1.036  . 

. 8.7 

1.134 

1.044  . 

. 10.4 

1.143 

1.052  . 

. 12.4 

1.152 

1.060  . 

. 14.4 

1.161 

1.067  . 

. 16.3 

1.171 

1.075  . 

. 18.2 

1.180 

1.083  . 

. 20.0 

1.190 

1.091  . 

. 21.8 

1.199 

Sugar 

Specific 

Sugar 

per  cent. 

gravity. 

per  cent. 

23.7 

1.210 

. . 46.2 

25.6 

1.221 

. . 48.1 

27.6 

1.231 

. . 50.0 

29.4 

1.242 

. . 52.1 

31.5 

1.252 

. . 54.1 

33.4 

1.261 

. . 56.0 

35.2 

1.275 

. . 58.0 

37.0 

1.286 

. . 60.1 

38.8 

1.298 

. . 62.2 

40.6 

1.309 

. . 64.4 

42.4 

1.321 

. . 66.6? 

44.3 

1.330 

(B.p.)  66.6? 

The  sp.  gr.  may  be  taken  by  an  hydrometer,  technically 
termed  a mccliarometer,  (The  above  spec,  gravs.  = 1°  to 
35°  Baume.) 

If  a liquid  contains  other  substances  besides  cane-sugar, 
the  test  of  specific  gravity  is  of  little  or  no  value.  Advan- 
tage may  then  be  taken  of  the  fact  that  syrup  causes  right- 
handed  twisting  of  a ray  of  plane  polarized  light  to  an 
extent  exactly  proportionate  to  the  amount  of  sugar  in  solu- 
tion. The  saccharine  fiuid  is  placed  in  a long  tube  having 
opaque  sides  and  transparent  ends  ; and  a ray  of  homoge- 
neous light,  polarized  by  refiection  from  a black-glass  mir- 
ror or  otherwise,  is  sent  through  the  liquid  and  optically 
examined  by  a plate  of  tourmaline,  NicoPs  prism,  or  other 
polarizing  eyepiece.  Attached  to  the  eyepiece  is  a short 
arm  which  traverses  a circle  divided  into  degrees.  The 
eyepiece  and  arm  are  previously  so  adjusted  that  when  the 
ray  is  no  longer  visible  the  arm  points  to  the  zero  of  the 
scale  of  degrees.  The  saccharine  solution,  however,  so 
twists  the  ray  as  to  again  render  it  visible  ; and  the  num- 
ber of  degrees  which  the  eyepiece  has  to  be  rotated  before 
the  ray  is  once  more  invisible  is  exactly  proportionate  to 
the  strength  of  the  solution.  The  value  of  the  degrees 


having  been  ascertained  by  direct  experiment  and  the 
results  tabulated,  a reference  to  the  Table  at  once  indicates 
the  percentage  of  sugar  in  the  liquid  under  examination. 


536 


QUANTITATIVE  ANALYSIS. 


Grape-sugar  also  possesses  the  property  of  dextro-rotation, 
but  less  powerfully  than  cane-sugar  ; moreover  the  former 
variety  does  not,  like  cane-sugar,  suffer  inversion  of  the 
direction  of  rotation  on  the  addition  of  hydrochloric  acid 
to  its  solution — an  operation  that  furnishes  data  for  ascer- 
taining the  amounts  of  cane-  and  of  grape-sugar,  or  of  crys- 
tallizable  and  non-ciwstallizable  sugar,  present  in  a mixture. 
In  using  the  polariscope-saccharometer,  it  is  convenient  to 
employ  tubes  of  uniform  size,  and  always  to  operate  at  the 
same  temperature. 


ALCOHOL. 

Mulder^s  process  for  the  determination  of  the  amount  of 
alcohol  in  wines,  beer,  tinctures,  and  other  alcoholic  liquids 
containing  vegetable  matter  is  as  follows  : Take  the  spe- 
cific gravity  and  temperature  of  the  liquid,  and  measure 
off  a certain  quantity  (100  cubic  centimetres);  evaporate 
to  one-half  or  less,  avoiding  ebullition  in  order  that  parti- 
cles of  the  material  may  not  be  carried  away  by  the  steam. 
Dilute  with  water  to  the  original  bulk,  and  take  the  specific 
gravity  at  the  same  temperature  as  before.  Of  the  figures 
representing  this  latter  specific  gravity,  all  over  1.000  show 
to  what  extent  dissolved  solid  matter  aflfected  the  original 
specific  gravity  of  the  liquid.  Thus,  the  specific  gravity 
of  a sample  of  wine  at  15°. 5 C.  is  0.9951 ; evaporated  till 
all  alcohol  is  removed  and  diluted  with  water  to  the  original 
bulk,  the  specific  gravity  at  15°.5  C.  is  1.0081:  0.0081  re- 
presents the  gravitating  effect  of  dissolved  solid  matter  in 
0.9951  parts  of  original  wine.  0.0081  subtracted  from 
0.9951  leaves  0.987,  which  is  the  specific  gravity  of  the 
water  and  alcohol  of  the  wine.  On  referring  to  a Table  of 
the  strengths  of  diluted  alcohol  of  different  specific  gravi- 
ties (p.  550),  0.987  at  15°.5  C.  is  found  to  indicate  a spirit 
containing  8 per  cent,  of  real  alcohol.  If  the  foregoing 
operation  be  conducted  in  a retort,  the  liquid  being  boiled 
and  the  steam  carefully  condensed,  the  distillate,  diluted 
with  water  to  the  original  bulk  of  wine  operated  on,  will 
still  more  accurately  represent  the  amount  of  water  and 
alcohol  in  the  wine — its  specific  gravity  showing  the  per- 
centage of  real  alcohol  present. 


DIALYSIS. 


537 


DIALYSIS. 

Dialysis  (from  6ta,  dia^  through,  and  lusis^  a loosing 
or  resolving)  is  a term  applied  by  Graham  to  a process  of 
analysis  by  diffusion  through  a septum.  The  apparatus 
used  in  the  process  is  called  a dialyzer^  and  is  constructed 
and  employed  in  the  following  manner.  The  most  conve- 
nient septum  is  the  commercial  article  known  as  parchment 
paper^  made  by  immersing  unsized  paper  for  a short  time 
in  sulphuric  acid  ; it  is  sold  by  most  dealers  in  chemical 
apparatus.  A piece  of  this  material  is  stretched  over  a 
gutta-percha  hoop,  and  secured  by  a second  external  hoop. 
Dialyzers  of  useful  size  are  one  or  two  inches  deep  and  five 
to  ten  inches  wide.  Liquids  to  be  dialyzed  are  poured  into 
the  dialyzer,  which  is  then  fioated  in  a flat  dish  containing 
distilled  water. 

The  practical  value  of  dialysis  depends  upon  the  fact 
that  certain  substances  will  diffuse  through  a given  septum 
far  more  rapidly  than  others.  Uncry stallizable  bodies 
diffuse  very  slowly.  Of  such  matters  as  starch,  gum, 
albumen,  and  gelatine,  the  last  named  is  perhaps  least 
diffusive  ; hence  substances  of  this  class  are  termed  colloids^ 
or  bodies  like  collin^  which  is  the  soluble  form  of  gelatine. 
Substances  which  diffuse  rapidly  are  mostly  crystalline ; 
hence  bodies  of  this  class  are  termed  crystalloids. 

Solutions  of  two  parts  of  the  following  named  substances 
in  100  parts  of  distilled  water  were  dialyzed  b}^  Graham  for 
twenty-four  hours.  The  amounts  of  each  substance  which 
passed  through  the  septum  bore  the  following  relations  to 
one  another ; — 


Chloride  of  sodium 1000 

Ammonium 847 

Theine 703 

Salicin  503 

Cane-sugar 472 

Amygdalin 311 

Extract  of  logwood  168 

Catechu 159 

Extract  of  cochineal 51 

Gallo-tannic  acid 30 

Extract  of  litmus 19 

Purified  caramel 5 


538 


DIALYSIS. 


Ten-per-cent,  solutions, under  similar  circumstances, 
the  following  results  : — 

Gum  Arabic 

4 

Starch -sugar 

266 

Cane-sugar 

214 

Glycerine 

440 

Alcohol 

476 

Chloride  of  sodium 

1000 

The  phenomena  of  dialysis  show  that  ciystalloids  are 
superior  to  colloids  in  affinity  for  water.  If  a solution  of 
chloride  of  sodium  be  placed  at  the  bottom  of  a jar,  and 
covered  by  a hot  solution  of  gelatine  of  sufficient  strength 
to  solidify  on  cooling,  the  chloride  of  sodium  will  diffuse 
up  into  the  solid  jell}^,  because  the  water  of  the  solid  jelly 
has  a greater  affinity  for  the  salt  than  it  has  for  the  gelatine. 
The  solid  jelly  may  obviously  be  reduced  in  thickness,  and 
saline  liquids  placed  above  it ; indeed  the  conditions  would 
then  be  still  more  favorable  for  diffusion.  Replace  the 
stratum  of  jelly  hy  a permanent  colloid,  suCh  as  parchment 
paper  ; the  result  is  the  same,  but  the  permanent  character 
of  the  septum  admits  of  its  practical  application. 

Further  researches  on  dialysis  will  probably  throw  much 
light  on  several  important  points  in  connection  with  phy- 
siological chemistry;  for  there  is  little  doubt  that  alimentary 
matter  passes  through  the  cell-walls  of  animals  and  plants 
hy  this  process. 


QUESTIONS  AND  EXERCISES. 

1055.  Carbonate  of  potassium  is  said  to  lose  16  per  cent,  of  water  ! 

on  exposure  to  a red  heat ; give  the  details  of  manipulation  observed  ' 
in  verifying  this  statement.  | 

1056.  Write  a few  paragraphs  descriptive  of  the  process  of  ulti- 
mate organic  analysis. 

1057.  In  what  forms  are  carbon,  hydrogen,  and  nitrogen  weighed 
in  quantitative  analysis  ? 

1058.  In  the  combustion  of  .41  of  a gramme  of  sugar,  what  weights 
of  products  will  be  obtained  ? — Ans.  .632  of  carbonic  acid  gas  tCO  J 
and  .237  of  water  (II.2O). 

1059.  Describe  De  Vry’s  process  for  the  assay  of  commercial 
quinia. 

1060.  Give  the  official  method  for  the  estimation  of  morphia  in 
opium. 


CONCLUSION. 


539 


1061.  Mention  the  operations  necessary  for  the  estimation  of  the 
proportion  of  sugar  in  saccharated  carbonate  of  iron,  or  in  a speci- 
men of  diabetic  urine. 

1062.  What  is  understood  by  saccharimetry  ? 

1063.  Give  two  processes  for  the  estimation  of  the  percentage  of 
alcohol  in  tinctures,  wines,  or  beer. 

1064.  Define  dialysis. 


Conclusion. 

Detailed  instructions  for  the  quantitative  analysis  of 
potable  water,  articles  of  food,  general  technical  products, 
special  minerals,  soils,  manures,  air,  illuminating  agents 
(including  solid  fats,  oils,  spirits,  petroleum,  and  gas),  dyes, 
and  tanning-materials,  would  scarcely  be  in  place  in  this 
volume. 

The  course  through  which  the  reader  has  been  conducted 
wdll,  it  is  hoped,  have  taught  the  principles  of  the  science 
of  chemistry,  and  given  special  knowledge  concerning  the 
applications  of  that  science  to  medicine  and  pharmacy,  as 
well  as  have  imparted  sufficient  manipulative  skill  to  meet 
the  requirements  of  manufacture  or  analysis.  The  author 
would  venture  to  suggest  that  this  knowledge  be  utilized, 
not  only  in  the  way  of  personal  advantage,  but  in  experi- 
mental researches  on  chemical  subjects  connected  with 
therapeutics  and  pharmacy.  The  discovery  and  publica- 
tion of  a new  truth,  great  or  small,  is  the  best  means  whereby 
to  aid  in  advancing  the  calling  in  which  we  may  be  engaged, 
benefit  our  fellow  creatures,  and  unveil  the  laws  of  the 
Creator  of  all  things. 


APPENDIX 


TABLE  OF  OFFICIAL  TESTS  FOE  IMPURITIES  IN 
PHAEMACOPCEIAL  PREPARATIONS  * 


Name  of  Preparation. 


Impurities. 


Tests. 


Acacise  Gummi  . . . 

Acelum 


r 

I 

Acidum  Aceticum  . 

I 

L 

Acid.  Acetic.  Glaciate  . 
Acidum  Boracicum.  . 

Acidum  Carbolicum  | 

r 


Acidum  Citricum  . ^ 

I 


Acidum  Gallicum  . . 

r 

Acidum  Hydrochlo-  J 
ricum  . \ 


Acidum  Hydrocya-  f 
nicum  Bilutum  . ) 


r 

I 

Acidum  Nitricum.  . 


Acidum  Oxalicum  . . 

r 


Acidum  Phosphor!-  ^ 
cum  Dilutum  . 


Starch  

More  than  one  thousandth 
of  Sulphuric  acid  . 
Traces  of  Lead  or  Copper 
Sulphuric  acid  . . . . 

Hydrochloric  acid  . . . 

Sulphurous  acid  . . . . 

Sulphurous  acid  . . . . 

Alkaliue  salts 

Creasote 

Traces  of  Copper  or  Lead 

Tartaric  acid 

Tartaric  acid 

Sulphuric  acid  . . . . 

Mineral  matter  . . . . 

Tannic  acid 

Sulphuric  acid  .... 

Arsenic 

Sulphurous  acid  . . * . 

Sulphuric  acid  .... 

Hydrochloric  acid  . . . 

Mineral  matter  .... 
Sulphuric  acid  . . . . 

Hydrochloric  acid  . . . 

Mineral  matter  .... 
Lead  or  Platinum  . . . 

Sulphuric  acid  .... 

Hydrochloric  acid  . . . 

Metaphosphoric  acid  . . 

Nitric  acid 

Phosphorous  acid  . . . 


Iodine 

Quantitative  analysis  . . 

Sulphuretted  Hydrogen  . 
Chloride  or  Nitrate  of  Ba- 
rium   

Niirate  of  Silver  . . . 

Nascent  Hydrogen  . . . 

Nascent  Hydrogen  . . . 

Insolubility  in  Alcohol  . 
Oxidation,  etc.  See  Crea- 

sotum 

Sulphuretted  Hydrogen  . 
Acetate  of  Potassium  . . 

Excess  of  Lime-water  . . 

Chloride  or  Nitrate  of  Ba- 
rium   

Incineration 

(Isinglass)  Gelatine . . . 

Chloride  or  Nitrate  of  Ba- 
rium   

Sulphuretted  Hydrogen, 

Copper 

Nascent  Hydrogen  . . , 

Chloride  or  Nitrate  of  Ba- 
rium   

Ppt.  by  Nitr.  silver,  insol. 

in  nitric  acid  .... 
Evaporation  and  ignition. 
Chloride  or  Nitrate  of  Ba- 
rium   

Nitrate  of  Silver  . . . . 

Incineration 

Sulphuretted  Hydrogen  . 
Chiwide  or  Nitrate  of  Ba- 
rium   

Nitrate  of  Silver  and  Nitric 

acid 

Albumen 

Ferrous  Sulphate  and  Sul- 
phuric acid 

Corrosive  sublimate  . . 


Page. 

245 

519 

197 

277 

240 

274 

274 

29(5 


392 

197 

28 

291 

277 

86 

317 

277 

148 

274 

277 

240 

86 

277 

240 

86 

229 

277 

240 

311 

256 

313 


* The  manipulations  necessary  to  be  observed  in  testing  for  impurities  will  be 
found  described  in  the  paragraphs  treating  of  those  substances.  The  Table  also  in- 
cludes references  to  processes  for  ascertaining  deticiency  in  strength  of  official 
articles. 

The  other  “characters  and  tests”  of  pharmacopoeial  compounds  have  been  given 
in  connection  with  the  respective  synthetical  and  analytical  reactions. 

46 


542 


APPENDIX 


Name  of  Preparation. 

Impurities. 

Test. 

Page. 

r 

Mineral  matter  . . . . 

Evaporation  and  ignition. 

86 

Acidiim  Sulphuri-  J 

Nitric  acid 

Ferrous  Sulphate  . . . 

256 

Arsenic  or  Lead  . . . . 

Sulphuretted  Hydrogen  . 

197 

Acidum  Sulpharosam. 

Sulphuric  acid  . . . . 

Chloride  or  Nitrate  of  Ba- 

rium   

277 

Acidum  Tannicum  . . 

Mineral  matter  . . . . 

Incineration 

86 

r 

Metallic  matter,  as  Lead  . 

Sulphuretted  Hydrogen  . 

197 

1 

Oxalic  acid 

Sulphate  of  Calcium  . . 

282 

Acidum  Tartaricum 

1 

Calcium  (tartrate  or  sul- 

Oxalate  of  Ammonium  . 

98 

phate). 

L 

Mineral  matter  . . . . 

Incineration 

86 

Aconitia 

Mineral  matter  . . . . 

Incineration 

86 

Adeps  prfeparatus  . | 

Chloride  (of  sodium)  . . 
Starch  (flour) 

Nitrate  of  Silver . . . . 

Iodine  

240 

24.5 

JEther 

Alcohol 

Boiling  point,  sp.  gravity. 

378 

JEther  Purus  . . . 

Alcohol,  Water  . . . . 

Specific  gravity  . . . . 

378 

Alcohol  ....  1 

Resin  or  oil 

Opalescence  on  dilution  . 

375 

Water 

Anhydrous  Sulphate  of 

Copper 

168 

Alcohol  Amylicum . . 

Other  spirituous  matter  . 

Boiling  point,  sp.  gravity. 

389 

Alum 

Iron  (sulphate)  . . . . 

Yellow  or  red  prussiate  . 

136 

Ammonii  Benzoas  . . 

Fixed  salts 

Non-volatility  . . . . 

85 

r 

Free  Bromine 

Odour  

241 

Ammonii  Bromidum-^ 

Iodide  (of  Ammonium).  . 

Chlorine  water  and  starch 

245 

1 

General 

Quantitative  analy8is(446) 

493 

f 

Fixed  salts 

Sulphate  (of  Ammonium). 

Non-volatility  . . . . 

Chloride  or  Nitrate  of  Ba- 

85 

Ammonii  Carbonas 

rium  

277 

Ammonii  Chloridum  . 

Chloride  (of  Ammonium). 

Nitrate  of  Silver  .... 

240 

Fixed  salts 

Non- volatility  . . . . 

85 

Ammonii  Nitras  . | 

Sulphate  (of  Ammonium). 

Chloride  of  Barium  . . . 

277 

Chloride  (of  Ammonium). 

Nitrate  of  Silver  .... 

240 

Amylum  . . . . | 

Alkaline  matter  . . . . 

Red  Litmus 

83 

Acid  matter 

Blue  Litmus 

83 

Antimonium  Nigrum  . 

Silica 

Insolubility  in  HCl . . . 

315 

Antimonii  Oxidum 

Higher  oxides  of  antimony 

Insolubility  in  sol.  of  acid 

tartrate  of  potassium 

156 

Antimonium  Tartara- 

General 

Quantitative  analysis  . . 

509 

tum. 

Sn) 

Aqua  Aurantii  Floris  . 

Metallic  matter  (Pb,  Cu, 

Sulphuretted  Hydrogen  . 

229 

r 

Fixed  salts 

Evaporation  and  ignition. 

86 

Tin,  Lead,  or  Copper  . . 

Sulphuretted  Hydrogen  . 

229 

Calcium  salts 

Oxalate  of  Ammonium  . 

98 

Aqua  Destillata  . . 

Chlorides 

Nitrate  of  Silver  . . . . 

240 

Sulphates 

Chloride  of  Nitrate  of  Ba- 

rium   

297 

Carbonates 

Lime-water 

280 

Argenti  Nitras  . . . 

r 

Other  nitrates,  etc.  . . . 

Metallic  silver  .... 

Quantitative  analysis,  etc. 
Effervescence  with  Nitric 

513 

Argenti  Oxidum  . 

acid 

191 

L 

General 

Quantitative  analysis  . . 

513 

Argentum  Purificatum 

Copper  

Ammonia  to  the  Nitric  so- 

lution   

169 

Atropia 

Mineral  matter  .... 

Incineration 

86 

Atropiae  Sulphas  . , 

Mineral  matter  .... 

Incineration 

86 

Balsamum  Peruvi-  < 

.Fixed  oil 

Immiscibility  with  Alcohol 

402 

anum ^ 

Alcohol 

Non-diminution  of  volume 

when  mixed  with  water 

374 

Beberia3  Sulphas  . . 

Mineral  matter  .... 

Incineration 

86 

Nitrates  (of  Bismuth  or 

Sulphate  of  Indigo  . . . 

258 

Bismuth!  Carbonas 

Ammonium). 

Lead  (carbonate)  . . . 

Diluted  Sulphuric  acid  . 

189 

1 

Chloride  (oxychloride  of 

Nitrate  of  Silver . . . . 

240 

1 

Bismuth!  Subnitras  | 

bismuth). 

Lead  (oxynitrate)  . . . 

Diluted  Sulphuric  acid  . 

179 

Chlorides  (oxychloride  of 

Nitrate  of  Silver . . . . 

240 

bismuth). 

APPENDIX 


543 


Name  of  Preparation. 

Impurities. 

Tests. 

Page. 

Bismuthum  Piirifica- 

Copper  

Ammonia  to  Nitric  solut’n 

169 

turn. 

r 

General 

Specific  gravity  (465)  and 

Bromum 

boiling  point 

449 

L 

f 

Iodine 

Zinc  (iodide) 

Starch 

Potash  in  excess,  then 

24.5 

Cadraii  lodidum  . 

Sulphydrate  of  Ammo- 
nium ....... 

222 

1 

General 

Quantitative  analysis  . . 

514 

Calcii  Carbonas  Prse-  f 

Alumina,  Oxide  of  Iron, 

Sacc.  solution  of  lime  to 

and  Phosphates. 

sol.  in  nitric  acid  . . . 

92 

cipitata  . . • 

Chlorides 

Nitrate  of  Silver  . . . . 

240 

Hypochlorite  of  Calcium 

Hydrochloric  acid  . . . 

260 

Calcii  Chloridum  . | 

Carbonic  acid 

Lime-water 

280 

r 

Carbonates  (of  Calcium)  . 

Effervescence  with  acids  . 

280 

Calcii  Phospbas.  . 

Alumina 

Solution  of  potash  . , . 

118 

Sand 

Insolubility  in  acid  . . . 

.815 

Calx 1 

Carbonate  of  Calcium  . . 

Effervescence  with  acids  . 

286 

Alumina,  Oxide  of  Iron, 

Sacc.  sol.  of  lime,  to  sol. 

etc. 

in  acids 

92 

Calx  Chlorata  . . 

General 

Quantitative  analysis  . . 

495 

Cambogia 

Starch  

Iodine  (Green)  . . . . 

245 

Campliora 

Fixed  salts 

Non-volatility  . . . . 

S3 

Carbo  Aniraalis  Purifi- 

Earthy  salts 

Incineration  (by  help  of 

86 

catus. 

red  ox.  of  mercury)  . . 

Carbo  Ligni  . . . . 

More  than  2 per  ct.  of  ash 

Incineration 

86  . 

Catechu  Pallidum  . . 

Starch  

Iodine  

24.5 

Cera  Alba 

Soft  Fats 

Melting-point 

451 

r 

Soft  Fats 

Melting-point 

451 

Cera  Flava  . . . ^ 

Resin 

Solubility  in  Alcohol  . . 

410 

L 

Flour 

tine.  Iodine 

245 

r 

Carbonates  and  other  oxa- 

Ash sol.  in  acids  with  ef- 

1 

Cerii  Oxalas  . . . 

lates. 

fervescence  

280 

Alumina 

Insolubility  of  Hydrate  in 

Ammonia 

203 

L 

General 

More  or  less  than  48  per 

cent,  of  ash 

203 

Cetaceum 

Soft  Fats 

Melting-point 

451 

Chloral | 

Chlorine 

Nitrate  of  silver  .... 

388 

General  

Quantitative  analysis  . . 

388 

r 

General 

Specific  gravity  .... 

450 

Chloroform  . . . ^ 

Hydrocarbons  . . 

Sulphuric  acid  .... 

386 

L 

Non-volatile  matter  . . 

Residue  on  evaporation  . 

86 

Copaiba 

o 

o 

Gelatinization  at  270°  F.  . 
Incomplete  solubility  in 

412 

Benzol 

412 

( 

Oxidation 

1 

Non-volatility  at  212°  F. 

392 

Creasotum  .... 

Carbolic  acid  ....-<( 

Dextro-rotation  of  polar- 

1 

ized  ray 

392 

Cupri  Sulphas  . . . 

L 

Crystallization  on  cooling 

392 

Iron  (ferrous  sulphate)  . 

Nitric  acid  and  ammonia 

137 

Elaterium  . . . . | 

Carbonates  (chalk)  . . . 

Effervescence  with  acids  . 

280 

General 

Quantitative  analysis  . . 

368 

Pel  Bovinum  Purifica- 

Mucus,  crude  bile  . . . 

Incomplete  solubility  in 

tura. 

spirit  . 

411 

Sulphate  of  (sodium)  . . 

Chloride  or  Nitrate  of  Ba- 

Fern Arsenias  . . 

rium  

297 

1 

General 

Quantitative  analysis  . . 

492 

Ferri  Carbonas  Sac-  f 

Sulphate  (of  ammonium)  . 

Chloride  or  Nitrate  of  Ba- 

297 

charata  . , . . 

rium  

General  ...  ... 

Quantitative  analysis  . . 

492 

f 

Tartrate  (of  iron  and  am- 

Ebullition with  potash  and 

Ferri  et  Ammonii  J 
Citras  . . . . j 

monium) 

saturation  with  Acetic 
acid  (=KHC4H^06)  . . 

287 

General 

Quantitative  analysis  . . 

507 

L 

Potassium  or  Sodium, salts 

Alkalinity  of  ash  . . . 

83 

544 


APPENDIX 


Name  of  Preparation, 

Impurities, 

Test. 

Page. 

Ferri  et  Quinife  Ci-  f 

Potassium  or  Sodium, salts 

Alkalinity  of  ash  . . . 

83 

General 

Quantitative  analysis  . . 

507 

1 1 ith ^ 

Alkaloids  other  than  Qui- 

Insolubility  of  ppid.  alka- 

nia. 

loid  in  ether 

344 

Ferri  Oxidum  Mag-  ^ 

Metallic  iron 

Effervescence  with  acids  . 

134 

neticam  . ( 

General 

Quantitative  analysis  . . 

492 

Ferri  Peroxidum  ( 
Humidum  . . . J 

Ferrous  hydrate  .... 

Ferric  oxyhydrate  . . . 

Red  prussiate  to  acid  so- 
lution   

Insolubility  in  cold  dil. 

136 

Hydrochloric  acid  . . 

129 

Arsenicum  (ferri  arsenias) 

Slip  of  Copper  in  acid  so- 

Ferri Phosphas  . . < 

lution  

148 

General 

Quantitative  analysis  . . 

492 

Ferri  Sulphas  . . f 

Ferric  oxysulphate  . . 

Insolubility  in  Water  . . 

122 

Ferri  Sulphas  Gra-  ! 

Ferric  compounds  . . . 

Ppt.  ofSiu  aqueous  sol. 

nulata  . . . . [ 

by  HgS 

L 

Copper,  etc 

Sulphuretted  Hydrogen  . 

229 

Ferrum  Kedactum  . . 

Less  than  50  per  cent.  . 

Quantitative  analysis  . . 

508 

Ferrous  compounds  . . 

Red  prussiate  to  acid  so- 

Ferrum Tartaratum 

Ammoniacal  salts  . . . 

lution  

Soda 

136 

82 

L 

General 

Quantitative  analysis  . . 

507 

Glycerina 

General  . 

Specific  gravity  . . . . 

394 

Hydrargyri  lodidum 

Fixed  salts 

Non-volatility  . . . . 

184 

Rubrum. 

Hydrargyri  lodidum 

Red  Iodide 

Insolubility  in  ether  . . 

172 

Viride. 

Hydrargyri  Oxidum  ) 
Flavum  . . . . ^ 

Fixed  Salts 

Non-volatility  . . . . 

184 

Hydrargyri  Oxidum  ^ 

Fixed  Salts 

Non-volatility  . . . . 

184 

Rubrum . ...  ( 

Nitrates  (of  mercury)  . . 

Orange  vapor  on  heating 

in  a tube 

179 

Hydrargyri Subchlo-  ^ 

Corrosive  Sublimate  . . 

Treatment  with  ether  . . 

178 

ridum ( 

Fixed  salts 

Non-volatility  . . . . 

184 

Hydrargyri  Sulphas 

Fixed  salts 

Non-volatility  . . . . 

184 

Hydrargyrum  . . . 

Fixed  meials  (Pb,  Sn,  Zn, 

Non-volatility  . . . . 

184 

Bi,  Cu). 

Hydrargyrum  Ammo- 

Fixed  salts 

Non-volatility  . . . . 

184 

niatum. 

Hydrargyrum  cum 

Mercuric  oxide  .... 

Stannous  chloride  to  sol. 

Greta. 

in  HCl 

183 

r 

Fixed  salts 

Non-volatility  . . . . 

243 

lodum ^ 

Cyanide  of  Iodine  . . . 

Physical  characters  . . 

243 

1 

General 

Quantitative  analysis  . . 

494 

Jalapse  Resina  . . , 

Resin 

Solubility  in  Turpentine  . 

369 

Limonis  Succus  . . . 

Deficiency  of  Citric  acid  . 

Quantitative  analysis  . . 

290 

Liquor  AmmOnise  . . 

General  . . . . . | 

Specific  gravity  • . . . 

Quantitative  analysis  . 

465 

476 

General  impurity  or  defi- 

Specific gravity  (449)  and 

ciency. 

Quantitative  analysis  . 

476 

Carbonate  of  Ammonium. 

Lime-water 

Calcium  .salts(chloride  etc. ) 

Oxalate  of  Ammonium  . 

98 

Liquor  Ammonise  ^ 
Fortior  . . . . ^ 

Iron  salts  (ferrous  hy- 
drate). 

Sulphydrate  of  Ammo- 
nium   

Sulphur  salts  (AmHS) . . 

Ammonio-sulphate  of  Cop- 

per   

272 

Chloride  of  Ammonium  . 

Sulphate  of  Ammonium  . 

Nitrate  of  Silver  to  acidi- 
fied sol 

Chloride  of  Barium  to  aci- 

240 

dified  sol 

Liq.  Antimonii Chlo-' 

ridi 

489 

Liq.  Arsenicalis  . . 

Li(i.  Arseuici  Hy- 

General  impurity  or  de- ^ 

1 

Specific  gravity  . . . j 

Quantitative  analysis  . | 

1 

509 

drochloricus  . . I 

Liq.  Bisinuthi  et  Am-  | 

flciency ^ 

489 

1 

mouii  Cit.  . . . J 

1 

1 510 

1 

APPENDIX 


645 


Name  of  Preparation. 

Impurities. 

Test. 

Page. 

Liq.  Calcis  . . . 

Deficiency  iu  strength . . 

Quantitative  analysis  . . 

478 

Liq.  Calcis  Chloratfe' 
Liq.  Calcis  Saccha- 
ratus 

General  impurity  or  de-  ^ 

Specific  gravity  .... 

466 

r 

ficiency ( 

Quantitative  analysis(o07) 

478 

r 

General  quality  . . . . 

Specific  gravity  .... 

465 

Liquor  Chlori  . . 

Fixed  matter  . . . . 

Kesidue  on  evaporation  . 

SO 

Deficiency  in  strength  . . 

Quantitative  analysis  . . 

495 

Liq.  Ferri  Perchlo-'^ 

ridi  Fort.  . . 

r 

Ferrous  salts 

Red  Prussiate 

1.37 

Liq.  Ferri  Perni-  ! 
tratis  . . . . j 

General  impuritv  or  de-  ^ 

Specific  gravity  . . . . 

465 

ficiency ( 

Quantitative  analysis  . . 

507 

Liq.  Ferri  Persul-  { 

t. 

phaiis  . . . J 

Liq.  Hydrargyri  Nit. 

Deficiency  in  strength 

Specific  gravity  .... 

466 

Acid 

Mercurous  salts  (nitrate)  . 

Hydrochloric  acid  . . . 

183 

Liq.  Litliii  Efferves- 

General  impurity  or  defi- 

Quantitative  analysis,  etc. 

201 

cens 

ciency. 

Liq.  Magnesii  Car-  ^ 
bonatis  . . . . ( 

Other  magnesian  salts 

Bitter  taste  (MgClaMgSO^). 

101 

General  impurity  or  defi- 

Quantitative  analysis  . . 

505 

ciency. 

Specific  gravity  . . . . 

Liq.  Plumbi  Subace- 

General  impurity  or  de-  < 

466 

latis 

ficiency ^ 

Quantitative  analysis  . . 

478 

' 

General  impurity  or  de-  J 

Specific  gravity  . . . . 

466 

ficiency ( 

Quantitative  analysis  . . 

478 

Carbonate(ofpotassium)  | 

Effervescence  with  acids  . 
Lime-water 

277 

280 

Calcium  salts 

Oxalate  of  Ammonium 

98 

Liquor  Potassse  . . - 

f Silica.  . . 

Insol.iu  acid  after  evap. etc. 

315 

1 Sulphates  . 

Chloride  of  Barium  to  acid 

More  than  < 
traces  of  | Chlorides  . 

sol 

Nitrate  of  silver  to  acid 

276 

1 

sol 

210 

I^Alumina.  . 

Ammonia  to  acid  sol.  . . 

117 

Liq.  Potassse  Effer-  \ 

Deficiency  in  strength  . . 

Quantitative  analysis  . . 

478 

vesceus  . . . . i 

i 

Bicarbonate  of  sodium  . . 

Tartaric  acid,  etc,  . . . 

500 

r 

General  impurity  or  de-  ^ 

Specific  gravity  . . . . 

466 

ficiency ( 

Quantitative  analy.sis  . , 

478 

Calcium  salts 

Oxalate  of  Ammonium 

98 

Liquor  Sodse  . . . - 

Carbonate  (of  sodium)  . | 

Effervescence  with  acids  . 
Lime-water 

280 

280 

f Silica.  . . 

Insol.  in  acids  after  evap 

315 

More  than  J Sulphates  . 
traces  of  , Chlorides  . 

BaClg  to  acid  sol.  . . . 

276 

AgN03  fo  acid  sol.  . . . 

210 

1 

L 

[^Alumina.  . 

Ammonia  to  acid  sol.  . . 

117 

1 

r 

Salts  of  Potassium  or  Am- 

Perchloride of  Platinum 

1 

Liquor  Soda3  Chlo-J 
ratse j 

1 

1 

monium  

General  impurity  or  defi- 

to acid  sol 

Quantitative  analysis  (65) 

83 

491 

i 

ciency. 

Calcium  salts 

Oxalate  of  Ammonium  . 

98 

Liq  Sodse  EfFeryescens 

Deficiency  in  strength  . . 

Quantitative  analysis  . 

478 

1 

r 

General  impurity  or  defi- 

Quantitative analysis  . . 

201 

Lithii  Carbonas  . . ^ 

1 

ciency. 

Calcium  salts 

Oxalate  of  Ammonium, etc. 

201 

1 

L 

Alumina 

Lime-water,  etc 

201 

Litbii  Citras  . . . 

Deficiency  in  strength  . . 

Quantitative  analysis  . . 

201 

Carbonate  (of  magnesium) 

Effervescence  with  acids  . 

102 

Magnesia  . . . . ^ 

Magnesia  Levis  . . 

Calcium  (hydrate  or  car- 
bonate). 

Sulphates  (of  magnesium 

Oxalate  of  Ammonium  to 

acet  sol 

Chloride  of  Barium  to  acid 

98 

or  sodium). 

sol 

276 

Alumina 

Ammonia  to  acid  sol.  . . 

117 

Sulphates  (of  magne.sium 

Chloride  of  Barium  to  acid 

or  sodium). 

solution 

276 

Magnesii  Carbonas 

Calcium  (carbonate)  . . 

Oxalic  acid  to  Ammonia- 

Magnesii  Carb.  Le-^ 

cal  solution 

98 

VIS 

Iron,  Lead,  etc 

Sulph.  hydrogen  to  sol.  in 

»• 

acid  excess  of  Ammon. 

229 

General  impurity  or  defi- 

Quantitative analysis  . . 

505 

ciency. 

40* 


546 


APPENDIX 


Name  of  Preparation. 

Impurities. 

Test. 

Page. 

r 

Calcium  (sulphate)  . . . 

Oxalate  of  Ammonium  . 

98 

Magnesii  Sulphas  . ^ 

Iron  (sulphate)  .... 

Chlorinated  Lime  or  Soda 

100 

L 

Geueral  impurities  . . . 

Quantitative  analysis  . . 

505 

Manna  

Deficiency  of  mannite  . . 

Quantitative  analysis  . . 

361 

Mel 

Starch  (flour) 

Iodine  

245 

Morphise  Hydrochloras 

r 

General  impurities  . . . 

Quantitative  analysis  . . 

533 

Fixed  oil 

Permanent  greasy  stain 

1 

Olea  Destillata  . . 

Alcohol 

on  paper  

Loss  in  volume  on  shak- 

1 

ing  with  water  . . . . 

Opium 

Deficiency  in  morphia 

Quantitative  analysis  . . 

532 

Plumbi  Acetas  . . . 

General 

Quantitative  analysis  . . 

478 

r 

Sulphate  of  Lead  or  Ba- 

Insolubility  in  Acetic  acid 

Plumbi  Carbonas  . ^ 

L 

rium  or  Silicates  . . . 

Calcium  (chalk)  .... 

(190,  88,  172) 
Oxal.  Ammonium  after  re- 

215 

moving  Lead  .... 

98 

Plumbi  Oxidum  . | 

Carbonates 

Effervescence  with  acids  . 

280 

Copper  (oxide)  . . . . 

Ammonia  to  acid  solution 

169 

r 

Potassa  Caustica  . 

More  than  fCtloride.  . 
traces  of  | Sulphates  . 

Nitrate  of  silver  to  acid 

solution 

Chloride  of  Barium  to  acid 

216 

1 

solution 

276 

L 

General  impurities  (water 

Quantitative  analysis  . . 

478 

Potassa  Sulphurata  . 

etc.). 

Excess  of  Carbonate  or 

More  than  25  per  cent,  in- 

Sulphate  

sol.  in  spirit 

57 

r 

Iron  and  other  metallic 

Sulphydrate  of  Ammo- 

Potassii Acetas  . . 4 

impurities 

nium  

229 

1 

Carbonate  of  Potassium  . 

Effervescence  with  acids  ; 

280 

alkalinity;  insolubility 

in  spirit 

57 

Potassii  Bicarbonas  . 

General 

Quantitativeanalysis  . . 

478 

r 

Free  bromine 

Odor 

211 

Potassii  Bromidum  { 

Iodide  (of  potassium)  . . 

Chlorine-water  and  starch 

216 

L 

General 

Quantitative  analysis  (487) 

515 

r 

fSilicate  . . 

Insol.  in  acid  after  evap. 

1 

Potassii  Carbonas  . 

More  than  ! c i i * 
traces  of  ^ Sulphal,  . 

elc 

Chloride  of  Barium  to  acid 
solution 

276 

1 

(.Chloride 

Nitr.  of  Silver  to  acid  sol. 

210 

L 

General • 

Quantitative  analysis  . . 

478 

Potassii  Chloras  . | 

Chloride  (of  potassium)  . 

Nitrate  of  Silver  . . . . 

240 

Calcium  (chloride)  . . . 

Oxalate  of  Ammonium 

98 

Potassii  Citras  . . . 

General 

Quantitativeanalysis  . . 

481 

Potassii  Ferridcyani-. 

Ferrocyanide  (of  potas- 

Ferric salt 

dum 

sium). 

r 

lodaie  (of  potassium)  . . 

Tartaric  acid  and  starch  . 

62 

Potassii  lodidum  . ■{ 

Chloride  (of  potassium)  . 

Nitrate  of  Silver,  etc.  . . 

210 

L 

Carbonate  (of  potassium). 

Sacc.  solution  of  Lime  . . 

92 

Potassii  Nitras  . . | 

Sulphate  (of  potas^ium)  . 

Chloride  of  Barium  . . 

276 

Chloride  (of  potassium)  . 

Nitrate  of  Silver  . . . 

240 

Potassii  Permanganas 

Geueral 

Quantitativeanalysis. 

493 

Potassii  Sulphas  . | 

Acid  Sulph.  of  Potassium 

Test-paper 

83 

Calcium  (sulphate).  . . 

Oxalate  of  Ammonium  .i 

98 

Potassii  Sulphis  . . 

Hyposulphite  (of  potas- 
sium). 

Sulphuric  acid  . . . . 

308 

Potassii  Tartras  . ^ 

Potassii  Tartr,  Acida  ] 

General 

Quantitative  analysis  . . 

481 

Quinife  Sulphas  . . j 

Salicin 

General 

Sulphuric  acid  .... 
Quantitative  analysis  . . 

370 

529 

Rhei  Radix  . . . . 

Turmeric 

Boracic  acid 

297 

Santoninum  . . . | 

Mineral  matter  . . . . 

Incineration 

86 

Earthy  soaps,  etc.  . . . 

Insolubility  in  spirit  . . 

401 

Sapo  Durus  . . . | 

Oil 

Oily  stain  to  paper  . . . 

401 

Potassium  compounds 

Deliquescence  of  ash  . . 

401 

Sapo  Mollis  ...  1 

Earthy  soaps,  etc.  . . . 

Insolubility  in  spirit  . 

1(11 

Oil 

Oily  stain  to  paper  . . . 

401- 

APPENDIX 


54t 


Name  of  Preparation 

Impurities. 

Test. 

Page. 

Resin  of  guaiacum  . . . 

Inner  surface  of  Potato- 

Scammonise  Kesina  ■< 

paring  

.369 

1 

Resin  of  Jalap  . . . . 

Insolubility  in  ether  . . 

369 

Carbonate  (of  calcium  and 

EfiTervescence  with  acids  . 

280 

Scammonium  . . 

magnesium). 

Starch  (flouij 

Solution  of  Iodine  . . . 

245 

Sinapis 

Starch  (flour) 

Solution  of  Iodine  . . . 

245 

[ 

More  than  ^ Chloride  . . 

Nitr.  of  Silver  to  acid  sol. 

210 

Soda  Caustica  . . 

traces  of  ^ Sulphate  . . 

Chloride  of  Barium  to  acid 
sol 

276 

1 

General  impurities  (water 

Quantitative  analysis  . . 

478 

etc  ). 

Soda  Tartarata  . . 

General 

Quantitative  analysis  . . 

481 

r 

Acid  or  alkaline  matter  . 

Test-paper 

83 

Soda  Acetas  . . . 

Sulphates  (sodium  or  cal- 
cium). 

Chloride  of  Barium  to  acid 
sol 

276 

1 

Chlorides  (sodium  or  cal- 

Nitrate  of  Silver  to  acid 

cium). 

sol 

240 

r 

Excess  or  deficiency  of 

Quantitative  analysis  . . 

487 

Sodii  Arsenias  . . ^ 

water  of  crystallization . 

L 

General 

Quantitative  analysis  . . 

487 

r 

Neutral  Carbonate  (of  so- 

Mercuric  chloride  . . . 

184 

1 

dium). 

Sodii  Bicarbonas  . •! 

More  than  < Chloride  . . 

traces  of  ^ Sulphate  . . 

Nitr.  of  Silver  to  acid  sol. 
Chloride  of  Barium  to  acid 

•240 

1 

sol 

276 

L 

General 

Quantitative  analysis  . . 

478 

Sodii  Boras  . . . . 

General 

Quantitative  analysis  . . 

478 

r 

Excess  or  deficiency  of 

Quantitative  analysis  . . 

525 

Sodii  Carbouas  . . ^ 

1 

water  of  cryst.  etc. 

More  than  ^ Chlorides  . . 

traces  of  ^Sulphates.  . 

Nitr.  of  Silver  to  acid  sol. 
Chloride  of  Barium  to  acid 

240 

sol 

276 

Sodii  Hyposulphis 

General 

Quantitative  analysis  . . 

489 

Sodii  Nitras  . . . | 

Chloride  (of  sodium)  . . 

Nitrate  of  Silver  . . . . 

240 

Sulphate  (of  sodium)  . . 

Chloride  or  Nitrate  of  Ba- 

rium   

276 

r 

More  than  trace  of  Sul- 

Chloride or  Nitrate  of  Ba- 

Sodii Phosphas  . . 

phate. 

rium  to  acid  sol.  . . . 

276 

L 

Deficiency  or  excess  of 

Quantitative  analysis  . . 

525 

water  of  cryst. 

Sodii  Sulphas  . . 

Ammonium  salts  . . ) 

Ferric  salts  . . . . ^ 

General 

Solut’n  of  potash  heated  | 
Quantitative  analysis  . . 

81 

137 

519 

L 

Excess  or  deficiency  of 

Quantitative  analysis  . . 

525 

water  of  cryst. 

Test-papers 

Insolubility  in  spirit  . . 

Sodii  Valerianas  . . 

Free  soda  or  carbonate  | 

83 

321 

r 

General 

Specific  gravity  . . ..  . 

466 

More  than  trace  of  acid  . 

EfiTervescence  with  bicar- 

Spiritus iEtheris  Ni-J 
irosi j 

Free  acid 

bonate  of  sodium  . . . 

More  than  “feeble”  effer- 
vescence with  bicarbo- 

280 

1 

nate  of  sodium  .... 

280 

1 

Deficiency  of  nitrite  of 

Quantitative  analysis  . . 

380 

Spiritus  Aramouio-  1 

[ethyl. 

Arornat 

Spiritus  Chloroformi  j 

General 

Specific  gravity  .... 

465 

, r 

General  (excess  of  water) 

Specific  gravity  .... 

465 

Spiritus  Rectificatus-^ 

Resin  or  oil 

Opalescence  on  dilution  . 

375 

1 

More  than  traces  of  fusil 

Nitrate  of  Silver  . . . . 

487 

oil,  etc. 

Spiritus  Tenuior  . . 

General  (excess  of  water). 

Specific  gravity  .... 

373 

Strychuia  . , . . | 

Brucia 

248 

Mineral  matter  .... 

Incineration 

86 

Sulphur  Prsecipita- ) 
turn ^ 

Sulphate  of  calcium  . 

Appearance  under  micro- 
scope   

271 

L 

Residue  on  ignition  . .| 

271 

548 


APPENDIX 


Name  of  Preparation 

Impurities. 

Test. 

Page. 

r 

Earthy  matter  .... 

Incineration 

86 

Sulphur  Sublima-  . 

Trace  of  Acid  (H2SO4  or 

Litmus-paper 

83 

turn 

H3SO3). 

Sulphide  of  Arsenicum 

Ammonia 

Sulphuris  lodidum 

Deficiency  of  Iodine  . . 

Quantitative  analysis  . . 

244 

Syrupi  

Deficiency  of  Sugar  . . . 

Specific  gravity  .... 

466 

Tamarind  us  . . . . 

Traces  of  Copper  .... 

Iron 

168 

Veratria  .... 

r 

Mineral  matter  .... 
Sulphates 

Incineration 

Chloride  or  Nitrate  of  Ba- 

86 

rium  

276 

Zinci  Acetas  . . . - 

Chlorides 

Nitrate  of  Silver . . . . 

240 

Metals  (As,  Cd,  Cu,  Pb)  . 
Iron  (acetate) 

Sulphuretted  Hydrogen  . 

229 

Nitric  Acid  : Ammonia  . 

139 

L 

Copper  (acetate)  .... 

Ammonia 

169 

1 

r 

Sulphates 

Chloride  or  Nitrate  of  Ba- 

1 

Zinci  Carbonas  . . -| 

1 

Chlorides 

rium  to  acid  sol.  . . . 

Nitr.  of  Silver  to  acid  sol. 

276 

240 

L 

Copper  (carbonate)  . . . 

Ammonia  to  acid  solution 

169 

1 

r 

Metals  (As,  Cd,  Cu,  Pb)  . 

Sulphuretted  Hydrogen  . 

229 

Sulphates 

Chloride  or  Nitrate  of  Ba- 

I 

Zinci  Chloridum  . ^ 

1 

1 

1 

Calcium  (chloride)  . . . 

rium  

Oxalate  of  Ammonium  . 

276 

98 

1 

1 

Ferrous  salts  (chloride)  . 

Ferridcyanide  of  Potass’m 

137 

1 

1 

Ferric  salts  (chloride) . . 

Ferrocyanide  of  Potass’m 

137 

Carbonate  (of  zinc)  , . . 

Sulphates  (sodium  or  zinc) 

Effervescence  with  acids  . 
Chloride  or  Nitrate  of  Ba- 

280 

Zinci  Oxidum  . . 

rium  to  acid  sol.  . . • 

276 

1 

1 

Clilorides 

Nitr.  of  Silver  to  acid  sol. 

240 

1 

Copper  (oxide)  . . . . 

Ammonia  to  acid  solution 

169 

f 

Metal  (As,  Cd,  Cu,  Pb)  . 
Iron  (sulphate)  . . . . 

Sulphuretted  hydrogen  . 

229 

Zinci  Sulphas  . . -< 

1 

Tincture  of  galls .... 
Nitric  acid:  Ammonia 

318 

139 

L 

Copper  (sulphate)  . . . 

Ammonia 

169 

r 

Sulphate  (of  zinc)  . . . 

Chloride  or  Nitrate  of  Ba- 

Zinci Valerianas  . ^ 

I 

rium  

276 

1 

Butyrate  (of  zinc)  . . . 

Acetate  of  Copper,  etc. 

322 

APPENDIX 


549 


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APPENDIX 


THE  PROPORTION  BY  WEIGHT  OF  ABSOLUTE  OR  PLAIN  ALCOHOL 
(C2H5HO)  IN  100  PARTS  OF  REAL  SPIRITS  OF  DIFFERENT 
SPECIFIC  GRAVITIES  (fOWNES). 


Sp,  gr.  at  60° 

Per- 

centage 

Sp.  gr.  at  60° 

Per- 

centage 

Sp.  gf.  at  60° 

Per- 

centage 

05°  5 C.). 

of  real 

(15°  5 C.). 

of  real 

(15°  5 C ). 

of  real 

0.9991  . 

alcohol. 

...  0.5 

0.9511  . 

alcohol. 

. . . 34 

0.8769  . . . 

alcohol. 

. 68 

0.9981  . 

...  1 

0.9490  . 

. . . 35 

0.8745  . . . 

. 69 

0.9965  . 

...  2 

0.9470  . 

. . . 36 

0.8721  . . . 

. 70 

0.994T  . 

. . . 3 

0.9452  . 

. . . 37 

0.8696  . . . 

. 71 

0.9930  . 

...  4 

0.9434  . 

. . . 38 

0.8672  . . . 

. 72 

0.9914  . 

...  5 

0.9416  . 

0.8649  . . . 

. 73 

0.9898  . 

. . . 6 

0.9396  . 

. . . 40 

0.8625  . . . 

. 74 

0.9884  . 

. . . 7 

0.9376  . 

. . . 41 

0.8603  . . . 

. 75 

0.9869  . 

. . . 8 

0.9356  . 

. . . 42 

0.8581  . . . 

. 76 

0.9855  . 

. . . 9 

0.9335  . 

. . . 43  - 

0.8557  . . . 

. 77 

0.9841  . 

. . . 10 

0.9314  . 

. . . 44 

0.8533  . . . 

. 78 

0.9828  . 

. . . 11 

0.9292  . 

. . . 45 

0.8508  . . . 

. 79 

0.9815  . 

. . . 12 

0.9270  . 

. . . 46 

0.8483  . . . 

. 80 

0.9802  . 

. . . 13 

0.9249  . 

. . . 47 

0.8459  . . . 

. 81 

0.9Y89  . 

...  14 

0.9228  . 

. . . 48 

0.8434  . . . 

. 82 

0.9718  . 

. . . 15 

0.9206  . 

. . . 49 

0.8408  . . . 

. 83 

0.9766  . 

. . . 16 

0.9184  . 

. . . 50 

0.8382  . . . 

. 84 

0.9753  . 

. . . 17 

0.9160  . 

. . . 51 

0.8357  . . . 

. 85 

0.9741  . 

. . . 18 

0.9135  . 

. . . 52 

0.8331  . . . 

. 86 

0.9728  . 

. . . 19 

0.9113  . 

. . . 53 

0.8305  . . . 

. 87 

0.9716  . 

. 20 

0.9090  . 

. . . 54 

0.8279  . . . 

. 88 

0.9704  . 

. . . 21 

0.9069  . 

. . . 55 

0.8254  . . . 

. 89 

0.9691". 

...  22 

0.9047  . 

. . . 56 

0.8228  . . . 

. 90 

0.9678  . 

. . . 23 

0.9025  . 

. . . 57 

0.8199  . . . 

. 91 

0.9665  . 

. . . 24 

0.9001  . 

0.8172  . . . 

. 92 

0.9652  . 

. . . 25 

0.8979  . 

. . . 59 

0.8145  . . . 

. 93 

0.9638  . 

. . . 26 

0.8956  . 

. . . 60 

0.8118  . . . 

. 94 

0.9623  . 

...27 

0.8932  . 

. . . 61 

0.8089  . . . 

. 95 

0.9609  . 

. . . 28 

0.8908  . 

. . . 62 

0.8061  . . . 

. 96 

0.9593  . 

. . . 29 

0.8886  . 

. . . 63 

0-8031  . . . 

. 97 

0.9578  . 

. . . 30 

0.8863  . 

. . . 64 

0.8001  . . . 

. 98 

0.9560  . 

. . . 31 

0.8840  . 

. . . 65 

0.7969  . . . 

. 99 

0.9544  . 

. . . 32 

0.8816  . 

. . . 66 

0.7938  . . . 

. 100 

0.9528  . 

. . . 33 

0.8793  . 

. . . 67 

APPENDIX. 


551 


THE  ELEMENTS. 


Aluminium  (Al/^)  . 

Antimony 

Arsenicum  (As^^^)  . 

Barium  . . . . . 

Beryllium  (Glucinum) 

Bismuth  (Bi^”) 

Boron 

Bromine  (79.75,  stas)  . 

Cadmium  .... 

Caesium 

Calcium  ..... 
Carbon  (C”)  . . . 

Cerium  (Ce^^)  .... 
Chlorine  (35.368,  stas)  . 

Chromium  (Cr/^)  . 

Cobalt  (Co”)  .... 

Copper 

Didymium  .... 
Erbium?.  . . . . 

Fluorine  ..... 
Glucinum.  See  Beryllium. 
Gold  (AuO  .... 
Hydrogen  .... 
Indium  .... 

Iodine  (126  533,  stas)  . 

Iridium  ..... 
Iron  (Fe”  & FeJ')  . 
Lanthanium  .... 
Lead  (”Pb”)  .... 
Lithium  (7.004,  stas)  . 
Magnesium  .... 
Manganese  (Mn”  & Mn^^) 

Mercury 

Molybdenum  .... 
Nickel  (Ni”)  .... 
Niobium  ..... 
Nitrogen  (N^  & N”^)  (14.009,  stas) 
Osmium  ..... 
Oxygen  (15.96,  stas) 

Palladium  . . . . 

Phosphorus  (P”^)  . 


Symbols  and  atomic 

Atomic 

value. 

weight. 

. 

2T.5 

. Sb^ 

122 

. As^ 

15 

. Ba” 

13T 

. Be" 

9.5 

. Br 

210 

. B'" 

11 

. Bi" 

80 

. Ccl" 

112 

. Cs' 

183 

. Ca" 

40 

. 

12 

. Ce^' 

92 

. OF 

35.5 

. Cr^' 

52.5 

. Co^' 

58.8 

. Cu" 

63.5 

. D" 

96 

. Eb" 

112.6 

. F' 

19 

. All"' 

196.1 

..  H' 

1 

t5.6 

. r 

127 

. 10^ 

197 

. Fe^* 

56 

. L" 

92 

. Pb'^ 

207 

. LF 

7 

. Mg" 

24 

. 

55 

• Hg" 

200 

. Mo^' 

96 

. Npi 

58.8 

. Nb^ 

97.6 

. N'^ 

14 

. 

199 

. 0" 

16 

. 

106.5 

. P'^ 

31 

552 


APPENDIX 


Platinum  (197.88,  Andrews) 

Symbols  and  atomic 
value. 

. Pt*’' 

Atomic 

weight. 

198 

Potassium  (39.04,  stas) 

. K' 

39 

Phodium 

. 

104.3 

Kubidium 

. Rb' 

85.3 

Piithenium 

. Ru'^ 

104.2 

Selenium 

. 

t9.5 

Silicon 

. 

28 

Silver  (107.66,  stas) 

• Ag' 

108 

Sodium  (22.98,  Stas)  . 

. Na' 

23 

Strontium 

. Sr" 

8Y.5 

Sulphur  (S^^  & S^^) 

. 

32 

Tantalum 

. Ta’^ 

182 

Tellurium 

. 

129 

Thallium  (203.  Cropkes) 
Tliorinum  or  Thorium 

. TP” 

204 

. Th" 

238 

Tin  (Sn'O 

. 

118 

Titanium 

Tiiv 

50 

Tungsten 

184 

Uranium. 

. 

120 

Yanadium 

. V'^ 

51.3 

Yttrium  . 

. Y" 

61.7 

Zinc 

. Zn” 

65 

Zirconium 

. ZP^ 

89.5 

Total . 

63 

The  quantivalence  or  atomic  value  of  some  elements  is,  apparentlj, 
variable  ; in  the  above  Table  the  full  coefficients  are  given  in  the 
column  of  symbols,  other  common  values  in  brackets. 

Atomic  weights  are  sometimes  obscurely  termed  equivalents. 


INDEX 


Abies  halsamea^  411 
excelsa,  411 
canadensis^  412 
Absinthin,  355 
Absinthium,  355 
Absinthol,  407 
Absolute  alcohol,  374,  449 
Acacice  gummi,  97 

gummi,  impurities  in,  541 
Acetate  of  ammonium,  solution  of, 
78 

amyl,  389 
ethyl,  268 
copper,  168 
iron,  117 
lead,  186 
morphia,  340 
potassium,  57 
sodium,  69 
zinc,  112 
Acetates,  265 

analytical  reactions  of,  265 
decomposition  of  aqueous  so- 
lution of,  266 

volumetric  estimation  of,  484 
Acetic  acid,  265,  266,  404 
ether,  268 
glacial,  266,  451 
volumetric  estimation  of  fn 
484 

Acetone,  268 

Acetonitrate  of  barium,  108 
Acetum,  265 

cantharidis,  265 
colchici,  265 
destillatum,  265 
impurities  in,  267,  541 
lobelice,  265 
opii,  265 
sanguinarice,  265 
scillcc,,  265 
Acetyl,  266 

47 


Acid,  acetic,  265,  266,  404 
acetic,  glacial,  266,  451 
aconitic,  289 
arable,  358 
angelic,  406 
arachidic,  404 
arsenic,  146 
arsenious,  144 
benzoic,  298,  413,  451 
boracic,  295 
bromic,  263 
butyric,  322,  404 
cantharidic,  409 
caproic,  404 
caprylic,  404 
carbazotic,  394 
carbolic,  391,  451 
carbolic,  impure,  394 
carbonic,  27,  278 
carminic,  300 
cathartic,  366 
cathartogenic,  366 
cerotic,  404 
cetraric,  300 
chloric,  259,  261 
cholalic,  401 
chromic,  211 
chrysophanic,  300 
chrysammic,  393 
cinnamic,  413 
citric,  289 
colopholic,  410 
colophonic,  410 
copaivic,  411 
cresylic,  392 
cryptophanic,  429 
cyanic,  300 
dextroracemic,  285 
dextrotartaric,  285 
dithionic,  307 
erucic,  403 
eugenic,  407 


554 


INDEX. 


Acid — 

equisetic,  289 
fluoric,  304 
formic,  300,  404 
gallic,  301,  318 
gambogic,  412 
gaultheric,  390 
glacial  acetic,  266,  451 
guaiaretinic,  369 
gnmmic,  258 
liemidesmic,  301 
hippuric,  301,  433,  436 
hydriodic,  243 
hydrobromic,  241 
• hydrochloric,  26,  238 
common,  238 
dilute,  238 

hydrocyanic,  247,  249 
dilute,  249 

hydroferridcyanic,  303 
hydroferrocyanic,  302 
hydrofluoric,  304 
hydrosulpliuric,  269 
hypochlorous,  260 
hypopliosphorous,  304 
hyposulphurous,  307 
iodic,  263 
jalapic,  369 
lactic,  309 
lauric,  404 
litliic,  320 
Isevoracemic,  285 
laevotartaric,  285 
malic,  309 
mastichic,  411 
meconic,  310,  424 
melissic,  404 
inetaboracic,  295 
metagummic,  258 
metantimonic,  157 
nietapliospboric,  310 
inetastannic,  215 
mimotannic,  318 
mucic,  365 
muriatic,  238 
myristic,  402 
myrrliic,  412 
naphthalic,  298 
nitric,  252,  254 
dilute,  255 

nitrobydrocbloric,  162,  255 
dilute,  162,  255 
nitromuriatic,  255 
nitrous,  311 


Acid — 

oenanthylic,  404 
oleic,  400 

orthophosphoric,  312 
oxalic,  282 
palmitic,  404 
paratartaric,  285 
pelargonic,  404 
pentathionic,  307 
perchloric,  262 
plienic,  391 

phospliomolybdic,  426,  427 
phosphoric,  22,  293,  312 
dilute,  293 
glacial,  294 
phosphorous,  312 
phthalic,  299 
picric,  394 
pimaric,  410 
pinic,  410 
polygallic,  371 
propionic,  404 
prussic,  247 
pyrogallic,  319 
pyroligneous,  365 
pyrophosphoric,  311,  312,  313 
racemic,  285 
rlieic,  300 
rhubarbaric,  300 
rutic,  404 
saccharic,  365 
salicylous,  390 
sarcolactic,  309 
silicic,  314 
stannic,  215 
stearic,  400,  404  < 

succinic,  315,  407 
sulphetbylic,  374 
sulpliindigotic,  258 
sulphindylic,  258 
sulpliocarbolic,  392 
sulphocyanic,  316 
sulphoplienic,  392 
sulpbovinic,  374 
sulphuric,  275 
sulphuric,  aromatic,  276 
dilute,  276 
sulphurous,  272 
sulphydric,  269 
sylvic,  410 
tannic,  316 
tartaric,  284,  315 
tetrathionic,  307 
tiglic,  402 


INDEX. 


555 


Acid — 

trinitrocarbolic,  392 
tritliionic,  307 
uric,  320 

valerianic,  320,  404 
Acid  carbonate  of  potassium,  58, 
408 

carbonate  of  sodium,  69 
salts,  61,  269 
solution  of  arsenic,  145 
tartrate  of  potassium,  52,  65 
tartrate  of  sodium,  66 
Acidimetry,  265 

Acids,  analytical  detection  of,  336 
antidotes  to,  237 
definition  of,  235 
of  chlorine,  262 
quanti tati  ve  estimation  of,  443 
volumetric,  estimation  of  offi- 
cial, 445 

Acidulous  radicals,  formulae  and 
quantivalence  of,  55,  104, 
236,  237 

radicals,  qualitative  detec- 
tion of,  323 

radicals,  quantitative  estima- 
tion of  salts  of,  514 
radicals,  tables  to  aid  in  the 
detection  of,  325,  326 
Acidum^  aceticum,  266 

aceticum^  impurities  in,  541 
aceticum  dilutum,  266 
aceticum  glaciate^  266 
aceticum  glaciale,  impurities 
in,  541 

arseniosum,  144 
henzoicum,  298 

horacicum,  impurities  in,  541 
' caj'holicum,  392 
carbolicum  impurum,  392 
chrornicum^  211 
citricum,  289 

citricuin,  impurities  in,  541 
gallicum,  318 

gallicum,  impurities  in,  541 
hgdrochloricum,  26,  239 
hydrochloricunij  impurities  in, 
541 

hydro chloricum  dilutum,  239 
hydrocyanicum  dilutum,  239 
hydrocyanicum  dilutum,  im- 
purities in,  541 
lacticum,  309 
nitricum,  255 


Acidum — 

nitricum,  impurities  in,  541 
nitricum  dilutum,  255 
nitro-h  ydrochloricum  dilutum, 
255 

nitro-muriaticum,  255 
oxalicum,  282 

oxalicum,  impurities  in,  541 
phosphoricum  dilutum,  293 
ptiosphoricum  dilutum,  impuri- 
ties in,  541 
sulphuricum,  276 
sulphuricum,  impurities  in, 
542 

sulphuricuin  aromnticum,  276 
sulphuricum  dilutum,  276 
sulphur osum,  273 
sulphurosum,  impurities  in  542 
tannicum,  317 

tannicum,  impurities  in,  542 
iartaricum,  285 

tartaricum,  impurities  in,  542 
valerianicum,  322 
Aconiti folia,  349 
radix,  349 
Aconitia,  349 

impurities  in,  542 
Aconitic  acid,  289 
Aconitina,  349 
Aconitine,  349 
Aconitum  napellus,  349 
Acrolein,  394 
Adeps  benzoatus,  401 
prceparatus,  401 
prceparatus,  impurities  in,  542 
u^gle  marmelos,  318 
Aerated  brq.ad,  362 
water,  71 
jEther,  376 
fortior,  378 
impurities  in,  542 
purus,  378 

purus,  impurities  in,  542 
Affinity,  chemical,  34 
Agate,  314 
Air,  composition,  24 

infiueiice  of  animals  and 
plants  on,  18 
nitrogen  in  the,  23 
oxygen  in  the,  15 
relative  weight  of  the,  24 
weight  of  1 cubic  cent.,  470 
weight  of  100  cub.  inch,  470 
Alabaster,  90 


556 


INDEX. 


Albumen,  395 

detection  of  in  urine,  429 
vegetable,  398 
Albumen  ovi,  395 
Albumenoid  substances,  395 
Alchemy,  13 
Alcohol^  372 

absolute,  374,  449 

amylic,  389,  449 

and  allied  bodies,  372  et  seq. 

benzylic,  413 

butylic,  322 

cinnamic,  413 

dilutum,  373 

ethylic,  373 

fortius,  373 

from  sugar,  362 

gl^^ceric,  394 

in  100  parts  of  spirits  of  dif- 
ferent densities,Table  show- 
ing the  proportion  of,  550 
methylic,  383 
phenic,  391 

quantitative  estimation  of, 
536 

radicals,  382 
real,  374 

test  for  impurities  in,  542 
test  for  purity  of,  375,  487 
Alcohol  amylicum,  389 

amylicum,  impurities  in,  542 
Alcoholates  of  chloral,  389 
Alcohols,  381 
Alcohometer,  466 
Aldehyd,  375 
benzoic,  299 
euodic,  408 
lauric,  408 
rutic,  408 
Aldehyds,  382 
Ale,  357 

Alexandrian  senna,  366 
Algarotli’s  powder,  156 
Alizarin,  415 

Alkalies,  analytical  separation  of 
the,  85 

antidotes  to,  237 
quantitative  estimation  of  the, 
478 

Alkalimetry,  482 
Alkaline  carbonates,  volumetric 
estimation  of  the,  478 
earths,  108 

solution  of  arsenic,  144 


1 Alkaloids,  338 

antidotes  to  the,  340 
distinguished,  339 
nomenclature  of,  339 
poisonous,  examination  . for, 
423  et  seq. 

Alkanet,  415 
Alkanna  tinctoria,  415 
Allium,  393 
Allotropic  bodies,  258 
Allotropy,  258  _ 

Alloxan,  320 
Alloy,  172 

Alloys,  analysis  of,  334 
Allyl,  393 

sulphide  of,  393 
sulphocyanate  of,  394 
Almond-oil,  402,  403 
Almonds,  oil  of  bitter,  366,  391 
oil  of  bitter,  test  fornitroben- 
zol  in,  299 

Aloe  harbadensis,  393 
socotrina,  393 
Aloins,  393 
Althcea,  310 
Alum  cake,  116 
Alum,  116 

chrome-,  116 
dried,  117 
1 -flour,  116 

iron-,  117 
potash-,  116 
roche  or  rock,  117 
soda-,  116 
Alumen,  116 

impurities  in,  542 
exsiccatum,  117 
I Alumina,  117 
j Aluminium,  115,  506 
! analytical  reactions  of,  117 

and  ammonium,  sulphate  of, 
106 

and  sodium,  double  chloride 
of,  116 
bronze,  116 
derivation  of  word,  29 
detection  of  in  presence  of 
iron  and  zinc,  139 
hydrate  of,  117 
oxide  of,  117 

quantitative  estimation  of, 
501 

separation  of  from  chromium 
and  iron,  213 


INDEX. 


55t 


Aluminium — 

silicate  of,  116 
sulphate  of,  116 
Amalgam,  172 

ammonium,  76 
Amber,  315 
oil  of,  315 

American  senna,  367 
turpentine,  408 
Amianth,  314 

Amido-chloride  of  mercury,  181 
Amines,  339 
Ammonia,  76 

fetid  spirit  of,  79 
gas,  composition  of,  77 
preparation  of,  77 
solution  of,  77 
volcanic,  76 

volumetric  estimation  of  solu- 
tions of,  478 
Ammoniacal  liquor,  76 
salts,  sources  of,  76 
Ammoniacum,  412 
Ammoniated  mercury,  181 
varieties  of,  181 
Ammonice  (vide  Ammonii) 

Ammonii  acetatis  liquor ^ 78 
aromaticus,  spiritiis,  79 
benzoas,  79,  299 
henzoas,  impurities  in,  498 
bromidum,  80 
carbonas^  78 

carbonaSj  impurities  in,  542 
chloridunif  76 

chloridum,  impurities  in,  542 
citratis,  liquor^  79 
foetidus,  spiritus,  79 
fortior,  liquor^  77 
iodidum,  80 
liquor,  77 
nitras,  257 

nitras,  impurities  in,  542 
phosphas,  79 
sulphas,  76 

Ammonio-cliloride  of  mercury, 
181 

-citrate  of  iron,  130 
-ferric  sulphate,  117 
-magnesian  phosphate,  103, 
294 

-nitrate  of  silver,  153,  182 
-sulphate  of  copper,  153,  182 
-sulphate  of  magnesium,  481 
-tartrate  of  iron,  130 


Ammonium,  75 

acetate  of,  78 
-amalgam,  76 
analytical  reactions  of,  82 
and  magnesium,  phosphate 
of,  103 

and  magnesium,  arseniate  of, 
103 

and  platinum,  double  chloride 
of,  88,  220 
arseniate,  146 
bicarbonate,  78 
benzoate  of,  79,  299 
bromide  of,  80 
carbamate,  78 
carbonate  of,  78 
carbonate,  solution  of,  79 
chloride  of,  76 
citrate  of,  79 
cyan  ate  of,  301 
derivation  of  word,  28 
derivatives,  182 
hydrate  of,  77 
nitrate,  257 
oxalate  of,  80 
phosphate  of,  79 
potassium,  and  sodium,  sepa- 
ration of,  85 

quantitative  estimation  of, 502 
salts,  source  of,  75 
salts,  volatility  of,  84 
sulphate,  76 
sulphide  of,  81 
sulphydrate  of,  80 
tartrate  of,  84 

volumetric  estimation  of  car- 
bonate of,  478 

Amorphous,  meaning  of,  160 
phosphorus,  293 
Amygdala  amara,  365,  403 
dulcis,  365,  403 
Amygdalin,  365 
Amyl,  381 

acetate  of,  389 
valerianate  of,  389 
Amylaceous  substances,  355 
Amylamine,  339 
Amylic  alcohol,  289,  449 
Amylum,  355 

impurities  in,  542 
Analogies  between  chlorine,  bro- 
mine, and  iodine,  244 
of  sodium  and  potassium 
salts,  73 


47* 


558 


INDEX. 


Analogy  (/f  salts,  73 
Analysis,  84 

aided  by  sifting,  330 
blowpipe,  331 
gas-,  319,  336 
gravimetric,  446,  497 
meaning  of  word,  53 
organic,  525 
practical,  84 
proximate,  525 
qualitative,  84 
quantitative,  445 
spectrum-,  336 
and  synthesis,  53 
systematic,  for  the  detection 
and  separation  of  the  me- 
tals, 85,  106,  139,  162,  165, 
195,  333 
ultimate,  525 
volumetric,  446,  475 
of  gases  and  vapors,  336 
of  insoluble  salts,  334  et  seq. 
of  medicines,  336 
of  salts,  323 

of  substances  having  un- 
known properties,  335 
Analytical  chemists,  14,  note. 

detection  of  the  acidulous 
radicals  of  salts  soluble  in 
water.  323 

memoranda,  230,  237 
Analytical  reactions  of 
acetates,  267 
albumen,  395 
alcohol,  374 
aldehyd,  376 
aluminium,  117 
ammonium,  82 
ainygdalin,  366 
antimony,  159,  419 
arsenicum,  148,  419 
atropia,  350 
barium,  88 
beberia,  350 
benzoates,  300 
berberia,  351 
bile,  401 
bismuth,  225 
borates,  297 
bromides,  242 
brucine,  348 
cadmium,  222 
cafl'eia,353 
calcium,  97 


Analytical  reactions  of — 

carbonates,  280 
chloral  hydrate,  387 
chlorates,  262 
chlorides,  240,  421 
chromates,  211 
chromium,  212 
citrates,  291 
cobalt,  207 
conia,  352 
copper,  168,  419 
cyanides,  250 
ferric  salts,  137 
ferridcyanides,  304 
ferrocyanides,  303 
ferrous  salts,  136 
fluorides,  304 
formates,  301 
gallic  acid,  319 
glucosides,  365 
i^lvcerine,  394 
gold,  218 
guaiacin,  369 
hippurates,  302 
hydrocyanic  acid,  250,  421 
hypochlorites,  260 
hypophosphites,  306 
hyposulphites,  308 
iodides,  245 
iron,  136 
lactates,  309 
lead,  189,  419 
lithates,  320 
lithium,  201 
magnesium,  102 
malates,  309 
manganese,  204 
meconates,  310,  424 
mercuric  salts,  180,410 
mercurous  salts,  180,  183 
metaphosphates,  310 
morphia,  341,  424 
nickel,  209 
nicotia,  352 
nitrates,  256 
nitrites,  311 
nitrous  ether,  379 
oxalates,  282,  421 
phosphates,  294 
phosphites,  313  * 
platinum,  219 
potassium,  64 
pyrogallic  acid,  319 
pyrophosphates.  313 


INDEX. 


559 


Analytical  reactions  of — 

qiiinia,  344 
salicin,  320 
silicates,  315 
silver,  193 
sodium,  74 
starch,  356 
strontium,  202 
strychnia,  347,  423 
succinates,  316 
sugar,  361 
sulphates,  277 
sulphides,  271 
sulphites,  273 
sulphocyanates,  316 
sulphuric  acid,  411 
tannic  acid,  317 
tartrates,  287 
theia,  353 
tin,  215,  216 
urates,  320 
veratria,  254 
zinc,  114 

Anchusa  tinctoria^  415 
Anchusin,  415 
Aneroid  barometer,  447 
Anethene,  406 
Angelic  acid,  406 
Angelic  powder,  156 
Angustura,  355 
Angusturin,  355 
Anhydride,  acetic,  266 
antimonic,  156 
antimonious,  156 
boracic,  297 
carbonic,  278 
chlorochromic,  212 
chromic,  211 
nitric,  252,  255 
nitrous,  257 
phosphoric,  22,  310 
silicic,  315 
sulphuric,  276 
sulphurous,  272 
Anhydrides,  70 
Anhydrous  bodies,  70 
nitric  acid,  255 
perchloride  of  iron,  125 
sulphate  of  copper,  168 
Aniline,  392,  417 
colors,  417 
Animal  charcoal,  95 

decolorizing  power  of, 
95 


Animal — 

rouge,  416 

Animals  and  plants,  complement- 
ary action  of  air,  18 
Anise,  406 
Anise-fruit,  406 
Aniseed-oil,  406 
Annatto,  415 

Anthemidis  Jiores,  355,  406 
Anthemis  nohilis^  406 
Anthracen,  393 
Anthracite,  213 
Antichlor,  273 
Antidotes  to  acids,  237 
alkalies,  237 
alkaloids,  340 
antimony,  161 
arsenic,  153 
barium,  88 
carbolic  acid,  392 
copper,  170 
cyanides,  250 
hydrochloric  acid,  241 
hydrocyanic  acid,  251 
lead,  190 
mercury,  184 
nitric  acid,  259 
oxalic  acid,  283 
silver,  195 
sulphuric  acid,  278 
tin,  216 
zinc,  115 

Antimonial  wine,  157 
Antimoniate  of  sodium,  74 
potassium,  74 
Antimonic  anhydride,  157 
chloride,  156 
oxide,  157 

Antimonii  chloridi,  liquor^  155,  509 
oxidum,  156 

oxidiirn,  impurities  in,  542 
et  potassoe  tartras,  157 
oxysulphuretum,  158 
sulphur  etum^  158 
Antimonious  anhydride,  156 
chloride,  155 
oxide,  156 
oxychloride,  156 
Antimonium  nigrum^  155 

nigrum,  impurities  in,  542 
sulphur  a turn.,  157 
tartaratum,  157,  284 
tartaratum,  quantitative  esti- 
mation of  antimony  in,  509 


560 


INDEX 


Antimoniuretted  hydrogen,  160 
Antimony,  143, 155,  284, 451,  509 
analytical  reactions  of,  159 
and  arsenic,  analytical  sepa- 
ration of,  162 

from  arsenic,  to  distinguish, 
151 

and  potassium,  tartrate  of, 
157,  284 
antidote  to,  161 
black,  1 55 
butter  of,  155 
chloride  of,  155 
crude,  155 

derivation  of  word,  29 
hydride  of,  160 
in  organic  mixtures,  detection 
of,  419 
oxide  of,  156 
oxychloride  of,  156 
oxysulphide  of,  157 
pentachloride  of,  157 
potassio-tartrate  of,  157 
quantitative  estimation  of, 
509 

solution  of  chloride  of,  155, 509 
sulphide  of,  155,  159 
sulphur  salts  of,  158 
sulphurated,  157 
tartarated,  157 
Antiseptic,  302 
AutoZone,  211,  245,  437 
Apatite,  295 
Apomorphia,  342 
Aporetine,  300 
Apparatus,  ix. 

for  experiments,  ix. 

for  volumetric  analysis,  475 

list  of,  ix. 

Apple,  essence  of,  390 
oil,  o90 
Aqua,  108 

Aqua  acidi  carholici,  391 
acidi  carhonici,  278 
ammonice,  77 
ammonicB  fortior,  77 
amygdalce  amaroe,  366 
aneihi,  405  • 
aurantii  Jioris,  405,  406 
aurautri  Jloris,  impurities  in, 
542 

camphorce,  400 
clilorinii,  25,  240 
creasoti,  392 


Aqua — 

desiillata,  109 

destillata,  impurities  in,  542 
fortis,  255 
laurocerasi,  366 
menthi^  piperitca,  405 
viridis,  405 
regia,  162,  255 
roscB,  405,  407 
Arabin,  97 
Arachidic  acid,  404 
Arhor  Dianoe,  194 
Arbutin,  318,  366 
Arctostaphglos  uva  ursi,  366 
Archil,  416 
Are,  456 
Argal,  284 

Argent-ammon-ammonium,  ni- 
trate of,  182 
Argenti  cyanidum,  194 
nitras,  193 

nitras,  impurities  in,  542 
oxldum,  193 

oxidum,  impurities  in,  542 
Argentic  chloride,  sulphide,  etc., 
vide  salts  of  silver. 
Argentiferous  galena,  191 
Argentum,  20,  192  r 
Argentum  purijicatum,  102 

purijicatum,  impurities  in, 
542 

Argol,  284 
Armenian  bole,  415 
Armoracioe  radix,  406 
Arnatto,  415 
Arnica,  411 
Arnicse  radix,  411 
Arnicin,  411 
Arnotto,  450 
Arrowroot,  357 
Arseniates,  146 
Arseniate  of  ammonium,  146 
barium,  89,  153 
calcium,  153 
copper,  153 
iron,  147,  492 

magnesium  and  ammonium, 
103 

silver,  153 
sodium,  146 

volumetric  estimation  of, 
489 
zinc,  153 
Arsenic  acid,  146 


INDEX. 


561 


Arsenic — 

and  arsenical  solutions,  volu- 
metric estimation  of  official, 
489 

anhydride,  146 
odor  of,  146 

in  carbonate  of  potassium, 
solution  of,  144 
in  hydrochloric  acid,  solution 
of,  145 
white,  144 
Arsenical  ores,  144 
sulphur,  152 
Arsenici  iodidum^  143 
Arsenicum,  143 

analytical  reactions  of,  148 
antidotes  to,  153 
and  antimony,  analytical  se- 
paration of,  162 
bromide,  143 
chloride,  143 
derivation  of  word,  29 
detection  of  in  metallic  cop- 
per, 149 

detection  of,  in  organic  mix- 
tures, 419 

Fleitmann’s  test  for,  150 
from  antimony,  to  distin- 
guish, 151 
hydride  of,  149 
iodide  of,  143 
Marsh’s  test  for,  149 
red  native  sulphide  of,  144 
quantitative  estimation  of, 
489,  508 

Reinsch’s  test  for,  148 
sources  of,  144 
sulphide  of,  144,  151 
yellow  native  sulphide  of,  144 
Arsenide  of  cobalt,  207 
Arsenio-sulphide  of  iron,  144 
of  nickel,  208 
Arsenious  acid,  144 
anhydride,  144 
Arsenites,  144 
Arsenite  of  copper,  153 
potassium,  144 
silver,  153 
sodium,  144 

Arsenuretted  hydrogen,  149 
Artemisia,  370 
Art  of  chemistry,  13 
Artificial  alkaloids,  339 
gastric  juice,  399 


Asbestos,  314 
Ash,  86 

black-,  73 
bone-,  94 
soda-,  73 

Ashes,  analysis  of  (mixed  solids), 
331 

Asparegin,  310 
Assafoetida,  412 
-ate,  meaning  of,  60 
Atmosphere,  carbonic  acid  in,  279 
composition  of,  24 
nitrogen  in,  23 
oxygen  in,  15,  24 
Atmospheric  pressure,  measure- 
ment of,  446 
Atom,  definition  of,  50 

weights,  definition  of,  45 
Atomic  proportions,  173,  176 
theory,  43 
weights,  43 
Atomicity,  45 
Atoms,  43, 44 

quantivalence  of,  47 
definition  of,  48 
Atropa  belladonna,  350 
Atropia,  350 

impurities  in,  542 
Atropice,  sulphas,  350 

sulphas,  impurities  in,  542 
Atropine,  350 
Attar  of  rose,  407 
Aurantii  cortex,  355,  406 
amari  cortex,  406 
dulcis  cortex,  406 
flores,  406 
Auric  chloride,  217 
sulphide,  217 
Aurum,  31 
Avence  farina,  356 
Avignon  grains,  414 
Avogadro’s  and  Ampere’s  law,  44, 
46 

Bael  fruit,  318 
Baking-powder,  362 
Balance,  453 
Balloons,  coal-gas  for,  21 
hydrogen  for,  21 
Balm-of-Gilead  fir,  412 
Balsam,  Canada,  412 
copaiva,  411 
fir,  408 
Peru,  413 


562 


INDEX 


Balsam — 

Storax, 413 
Tolu,  413 

Bahamodendron  myrrha,  412 
Balsamum  Peruvianum,  413 

Peruvianum,  impurities  in, 
642 

Tolutanwnij  413 
Balsams,  413 
Barbaloin,  393 

Baric  chloride,  nitrate,  etc.,  vide 
salts  of  barium. 

Barii  carhonas,  87 
Barium,  87 

acetonitrate  of,  108 
analytical  reactions  of,  88 
and  calcium,  separation  of, 
from  magnesium,  106 
antidotes  to,  88 
arseniate  of,  89 
carbonate,  89 
native,  87 
cnrbonate  of,  87 
chloride  of,  87 
chromate  of,  88 
derivation  of  word,  28 
detection  of,  in  presence  of 
calcium  and  magnesium, 
85,  106 

hydrate  of,  88 
nitrate  of,  87 
peroxide  of,  88 
phosphate  of,  89,  295 
oxalate  of,  89,  282 
quantitative  estimation,  502 
salts,  antidote  to,  88 
silico-fluoride  of,  89 
sulphate  of,  88 
sulphide  of,  88 
sulphite,  274 
Barley-sugar,  364 
Baronieter,  446 
Baryta,  88 

-water,  88 
Basalt,  116 

Base,  meaning  of,  237 
organic,  338 
Bassorin,  97,  358 
Bastard  satfron,  415 
Bauxite,  116 
Basylous  radicals,  104 
Bay  rum,  372 
Bay-salt,  67 
Bearberry,  318 


Beaver,  411 
Beherice  sulphas,  350 

sulphas,  impurities  in,  542 
Beberia  or  beberine,  350 
Beer,  257 
Beetroot,  361 
Belm  fructus,  318 
Belladonnce  folia j 350 
radix,  350 
Bell-metal,  213 
Bend  glass  tubes,  to,  16 
Benzine-collis,  391 
Benzoate  of  ammonium,  79,  299 
Benzoated  lard,  401 
Benzoates,  298 
Benzoic  acid,  298,  449,  451 
aldehyde,  299 
glycocine,  302 
Benzoin,  298,  413 
Benzoinum,  298,  413 
Benzol,  391,  449 
Benzoyl,  hydrate  of,  299 
hydride  of,  366,  413 
Benzyl,  benzoate  of,  413 
cinnamate  of,  413 
Benzylic  alcohol,  413 
Berberia  or  berberine,  351 
Bergamot  oil,  406 
Berlin  blue,  416 
red,  415 

Berryllium,  507 
Bi-,  the  prefix,  59 
Bibasic,  vide  Dibasic. 

Bibulous  paper,  93 
Bicarbonate  of  ammonium, 78 

of  potassium,  58,  286,  290, 478 
of  sodium,  69,  286,  290,  478 
Bichromate  of  potassium,  210 
Bile,  401 

detection  of,  in  urine,  430 
test  for  presence  of,  401 
Biliary  calculi,  441 
Bismuth,  222.  451,  467,  510 

and  ammonium,  solution  of 
citrate  of,  225 
analytical  reactions  of,  225 
carbonate  of,^24 
citrate  of,  225 
derivation  of  word,  31 
-lozenge,  224 
nitrate  of,  223 

quantitative  estimation  of, 
510 

-salts,  composition  of,  225 


INDEX 


563 


Bismuth— 

subcarconate  or  oxycarbon- 
ate,  224 

subnitrate  or  oxynitrate  of, 
223 

subnitrate  of,  223 
sulphate  of,  225 
sulphide  of,  226 
Bismuthi  carbonas,  224 

carbonas,  estimation  of  bis- 
muth in,  510 

carbonas^  impurities  in,  542 
subcarbonas^  224 
subnilras,  223 
Bismuthum^  223 

purijicatum^  223 
purijicaturriy  impurities  in, 
543 

Bisulphide  of  carbon,  382 
Bitter  almonds,  oil  of,  366,  391 
cassava,  356 
principles,  355 
sweet,  353 

Bituminous  coal,  213 
Bivalence,  47 

Bivalent  radicals,  47,  105,  108 
Bixa  07'ellanaj  415 
Bixin,  415 

Black  antimony,  155 
-ash, 73 
-band,  119 
bone-,  94 

coloring-matters,  414 
dyes,  417 
flux,  145 

hydrate  of  iron,  133 
ink, 318 
-lead,  26 

oxide  of  copper,  169 
oxide  of  iron,  134 
oxide  of  manganese,  203 
oxide  of  mercury,  179 
pepper,  353 
Black  oak,  415 
Bladder-green,  416 
Blanc  de  Perle,  224 
Bleaching  by  chlorine,  25 
-liquor,  97 
-powder,  96 
Blende,  109 
Block  tin,  213 
Blood,  396,437 

detection  of  in  organic  matter, 
437 


Blood — 

hydrocyanic  acid  in  the,  251 
Blood-root,  353 
Bloodroot  vinegar,  265 
Blood-stains,  437 
Blowpipe-analysis,  331 
-flame,  331 

Blue  coloring-matters,  416 
copperas,  121 
indigo,  258 
ointment,  171 
pill,  171 

Prussian,  137,  303 
stone,  168 
Turnbull’s,  304 
vitriol,  121,  168 

Boiling-points  of  various  sub- 
stances, 449,  450 
“Bonds”  (Frankland),  114 
Bone-ash,  94 
-black,  94 
-earth,  292 

Bones,  composition  of,  292 
Boracic  acid,  296 
anhydride,  296 
Borates,  296 

analytical  reactions  of,  297 
Borax,  297 

volumetric  estimation  of, 
480 

Borax  bead,  205 
Bordeaux  turpentine,  408 
Borneeiie,  409 
Borneo  camphor,  409 
Boron,  297 

chloride  of,  297 
derivation  of  word,  30 
flame,  298 
fluoride  of,  297 

Borotartrate  of  potassium,  297 
Bos  taunts,  401 
Bourdon  barometer,  447 
Brandy,  376 
Brass,  109 
Brazil  wood,  415 
Bread,  356,  362 
aerated,  362 
making,  362 
Brezilin,  415 
Bright’s  disease,  430 
Britannia  metal,  155,  185,  214 
British  gum,  357 
Bromal,  389 

alcoholates  of,  389 


564 


INDEX. 


Bromal — * 

hydrate  of,  389 
Bromate  of  potassiuiii,  63 
Bromates,  263 
Bromic  acid,  63,  263 
Bromide  of  ammonium,  242 
arsenicum,  143 
iron,  124 

potassium,  63,  241 
potassium,  volumetrical  esti- 
mation of,  487 
of  silver,  194 
of  sulphur,  272 
Bromides,  241 

analytical  reactions  of,  242 
quantitative  analysis  of,  487, 
515 

separation  of,  from  chlorides 
and  iodides,  246 
Bromine,  241 

analytical  separation  of,  242 
derivation  of  word,  39 
its  analogy  to  chlorine  and 
iodine,  243 
solution  of,  242 
volumetric  estimation  of  free, 
515 

Brominium,  241 
Bromum,  241 

impurities  in,  543 
Bronze,  214 

aluminium,  116 
coinage,  167 
Bronzing-powder,  216 
Broom-tops,  353 
Brown  coloring-matters,  417 
haematite,  119 
rosin,  410 
sugar,  361 
Brucia,  248 
Brucine,  248 
Brunswick  green,  152 
Buchu  folia,  355 
Buchu,  oil  of,  406 
Bucktliorn-green,  416 
-juice,  367 

Bunsen  gas-burners,  21 
Burette,  Mohr’s,  476 
Burgundy  pitch,  411 
Burners,  gas-,  17,  21 
Burnett’s  disinfecting  fluid.  111 
Burnt  sugar,  361 
ochre,  415 
umber,  417 


Butter,  398 

of  antimony,  155 
of  orris,  407 
Butyl,  322 

sulphocyanate,  382 
Butylic  alcohol,  322 
Butyrates,  322 
I Butyric  acid,  322,  404 
By-products,  176 

Cacao  oil,  402 
Cadmii  iodidum,  221 
' iodidum,  impurities  in,  543 
I Cadmium,  221 

analytical  reactions  of,  222 
carbonate,  222 
derivation  of  word,  31 
hydrate  of,  222 
iodide  of,  221 
nitrate,  222 
sulphate,  222 
sulphide  of,  222 
Ccesalpinia  hraziliensis,  415 
Caesium,  551 
Caffeia,  353 
Cajuput  oil,  406 
Caking  coal,  213 
Calabar  bean,  353 
Calamine,  109 

Calcic,  sulphate,  phosphate,  etc., 
vide  salts  of  calcium. 

Calcii  carbonas  prcecipitata,  92 
carhonas  prcecipitata,  impuri- 
ties in,  543 
chloratce,  liquor,  97 
chloridnm,  90 

chloridum,  impurities  in,  543 
hydras,  92 
phosphas,  94 

phosphas,  impurities  in,  543 
saccharatus,  liquor,  92 
Calcined  magnesia,  102 
Calcium,  90 

analytical  reactions  of,  97 
and  barium,  separation  from 
magnesium,  106 
carbonate  of,  92 
prepared,  94 
chloride  of,  90 
chromate  of,  98 
citrate  of,  291 
derivation  of  word,  29 
-flame,  98 
fluoride  of,  90 


INDEX. 


665 


Calcium — 

fluoride  of,  in  bones,  95 
gummate  of,  97 
hydrate  of,  91 
hypochlorite  of,  96 
hypophosphite  of,  305 
hyposulphite  of,  270 
in  presence  of  barium  and 
magnesium,  detection  of, 
106 

oxalate  of,  98,  282 
oxide  of,  91 
phosphate  of,  90,  94 
polysulphide  of,  270 
quantitative  estimation  of,  504 
silicate  of,  90,  314  . 
sulphate  of,  90,  97,  271 
sulphite  of,  274 
superphosphate  of,  292 
tartrate  of,  287 
Calc-spar,  90 
Calculi,  urinary,  439 

urinary,  examination  of,  439 
Calomel,  171,  176 

test  for  corrosive  sublimate 
in,  178 

tests  for  constituents  of,  178 
Calumhcc  radix,  351 
Calx,  91 

impurities  in,  543 
chlorinata,  96 
chlorata,  96 

chloraia,  impurities  in,  543 
Cambogia,  412 

impurities  in,  543 
Camphor-laurel,  409 
mixture,  409 
oil,  409 
water,  409 
Camphora,  409 

impurities  in,  543 
officinarum,  409  ^ 

Camphors,  409 
Camwood,  415 
Canada  balsam,  412 
Canadian  turpentine,  408 
Canarium  commune,  412 
Candle-flame,  composition  of,  21 
Canellce  albce  cortex,  355 
Cane-sugar,  361 
Canna,  357 
Cannabin,  411 
Cannabis  indica,  41 
Cantharides,  409 
48 


Cantharidic  acid,  409  * 
Cantharidin,  409 
Cantharis,  409 
Caoutchouc,  413 
Capacity  unit,  455 
Capillary,  448 
Caproate  of  glyceryl,  402 
Caproic  acid,  402,  404 
Caproyl,  381 

Caprylate  of  glyceryl,  402 
Caprylic  acid,  402,  404 
Capsid  fructus,  351 
Capsicia,  351 
Capsicine,  351 
Capsicum,  351 

fruit,  resin  of,  349 
oil  of,  351 
Caramel,  364 
Caraway  oil,  407 
Carbamate  of  ammonium,  78 
Carbazotic  acid,  392 
Carbolic  acid,  391,  449,  451 
acid,  antidote  to,  392 
Carbon,  26 

bisulphite  of,  382 
combustion  of,  26 
derivation  of  word,  28 
quantitative  estimation  of,  in 
organic  compounds,  525  et 
seq. 

Carbo  animalis,  95 

animalis  purificatus,  95 
animalis  pur  ifitatus,  impurities 
in,  543 
ligni,  95 

ligni,  impurities  in,  499 
Carbonate  of  ammonium,  78 
ammonium,  solution  of,  78 
barium,  89 
bismuth,  225 
cadmium,  222 
calcium,  90,  92 
prepared,  94 
iron,  122,  492 

iron,  saccharated,  123,  492 
lead, 185 
lithium,  201 
magnesium,  100 
potassium,  52,  478 
potassium  acid,  58,  478 
sodium,  68,  73,  279,  478 
sodium,  acid,  69,  478 
sodium,  manufacture  of,  86, 
279 


566 


INDEX. 


Carbonate  — 

strontium,  202 
zinc,  109,  112 
Carbonates,  278 

acidulous  radical  in,  278 
analytical  reactions  of,  280 
gravimetric  estimation  of,  519 
volumetric  estimation  of  alka- 
line, 478 

Carbonic  acid,  27,  279 
anhydride,  279 
generation  of,  59 

Carbonic  acid  gas,  solubility  of,  in 
water,  71 
oxide,  283,  303 
Carbonization,  86 
Cardamom  oil,  406 
Cardamomum^  406 
Carmine,  300 
Carminic  acid,  300 
Carnallite,  54 
Carrageen  moss,  358 
Carrotin,  415 
Carthamin,  416 
Carthamus  tinctorius,  415 
Carvene,  407 
Carum,  407 
Carvol,  407 
Caryophyllin,  407 
Cascarilla  oil,  407 
Cascarilla  cortex,  407 
Casein,  397 

vegetable,  398 
Cassia  marilandica,  367 
Cassia  oil,  407 
Cassice  pulpa,  361 
Castilloa  elastica,  413 
Cast-iron,  119,  451 
Castor,  411 
Castor  fiber,  411 
Castor  oil,  403 
Castoreum,  411 
Castorin,  411 
Catechu,  318 
Catechu  pallidum,  318 

pallidum,  impurities  in,  543 
Cathartic  acid,  366 
Cathartogenic  acid,  367 
Caustic,  193 
lime,  91 
lunar,  191 
potash,  53 
soda,  68 

Cayenne  pepper,  351 


Cedra  oil,  406 

Celestine,  202 

Cellulin,  359 

Cellulose,  359 

Celsiuses  thermometer,  448 

Cements,  314 

Centiare,  455 

Centigrade  thermometer,  448 
Cephalis  ipecacuanha,  352 
Cerasin,  358 

Ceratum  plumhi  suhacetatis,  vide 
Unguentum, 
zinci  carbonatis,  112 
Cera  alba,  402 

alba,  impurities  in,  543 
fiava, 402 

fiava',  impurities  in,  543 
Cerebrin,  396 
Cerite,  203 

Cervisice  fermentum,  372 
Cerii  oxalas,  203 

oxalas,  impurities  in,  543 
Cerium,  203 

derivation  of  word,  30 
oxalate  of,  203 
Ceroleine,  402 
Cerotic  acid,  402 
Cetaceum,  402 

impurities  in,  543 
Cetene,  402 
Cetraria,  300 
Cetraric  acid,  300 
Cetyl,  hydrate  of,  402 
palmitate  of,  402 
Cevadilla,  354 
Chalcedony,  314 
Chalk,  94 

precipitated,  92 
prepared,  94 
-stones,  441 
Chalybeate  water,  119 
Chameleon,  mineral,  205 
Chamomile  oil,  406 
Char,  86 
Charcoal,  26 
animal,  94 

animal,  decolorizing  power  of, 
94 

wood,  95 
Cheese,  397 

Chemical  action,  definition  of,  34 
Chemical  action  by  symbols,  illus- 
tration of,  37,  40 
affinity,  34 


INDEX. 


5G7 


Chemical — 

combination,  34 
combination  by  weight,  laws 
of,  40  et  seq. 

combination  by  volume,  laws 
of,  44  et  seq. 

combination  different  from 
mechanical,  33,  35 
combination,  laws  of,  40,  171, 
257,  445,  497 

compound,  definition  of,  48 
compound,  27 
diagram,  49,  54 
equation,  49,  54 
force,  36 

force,  conditions  for  the  mani- 
festation of,  36 
formula,  definition  of,  49 
formulae,  37,  38,  39 
notation,  37,  38,  39 
preparations  of  the  Pharma- 
copoeias, 444 

philosophy,  principles  of,  33 
et  seq. 

symbol,  definition  of,  49 
symbols,  37,  38,  39 
toxicology,  418 
Chemist  and  Druggist,  14 
Chemicals,  14 
list  of,  xi. 

Chemism,  34 
Chemistry,  art  of,  13 

and  physics,  differences  be- 
tween, 43 
definition  of,  48 
derivation  of  the  word,  13 
inorganic,  338 
object  of,  14,  43 
organic,  338 
science  of,  13 
Chemists,  analytical,  14 
manufacturing,  14 
pharmaceutical,  14 
Chenopodlum^  408 
Cherry-laurel  water,  366 
Cherry-tree  gum,  358 
Chestnut-brown,  417 
Chian  turpentine,  408 
Chili  saltpetre,  252 
Chimaphila,  355,  366 
Chimaphila  umbellatciy  366 
Chinese  red,  415 
yellow,  414 
Chirata^  355,  366 


Chiratin,  367 
Chloral^  386 
Chloral  hydrate,  386 
alcoholates  of,  389 
Chlorate  of  potassium,  261 

potassium,  preparation  of  oxy- 
gen from,  16 
Chlorates,  261 

analytical  reactions  of,  262 
Chloric  acid,  260 
Chloride  of  ammonium,  76 
antimony,  155 
arsenicum,  143 
barium,  87 
boron,  297 
calcium,  90 

calcium,  removal  of  iron  from, 
90 

chromium,  210 

gold,  218 

iron,  125 

lead,  189 

lime,  96 

magnesium,  99 

manganese,  204 

mercuric  ammonium,  182 

mercurous  ammonium,  182 

mercury,  176 

platinum,  219 

platinum  and  ammonium,  83, 
503 

platinum  and  lithium,  201 

platinum  and  potassium,  65 

silicon,  315 

silver,  192 

sulphur,  272 

tin,  214 

solution  of,  214 
zinc.  111 
Chlorides,  238 

separation  of,  from  bromides 
and  iodides,  246 
tests  for,  240 
estimation  of,  514 
Chlorinated  lime,  96 

volumetric  estimation  of,  495 
soda,  solution  of,  72 

volumetric  estimation  of, 
495 

Chlorine,  24,  239,  514 
acids,  262 

as  a disinfectant,  25 
bleaching  by,  25 
collection  of,  24 


568 


INDEX 


Chlorine — 

derivation  of  word,  28 
its  analogy  to  bromine  and 
iodine,  243,  246 
preparation  of,  24 
properties  of,  24 
relative  weight  of,  25 
solubility  in  water,  25 
the  active  agent  in  bleaching- 
powder,  96 

volumetric  estimation  of,  495 
water,  24,  240 

Chlorochromic  anhydride,  212 
Chloroform,  385,  450 
impurities  in,  543 
Chlorophyll,  416,  443 
Chocolate,  402 
Cholalic  acid,  401 
Cholate  of  sodium,  401 
Cholesterin,  396,  441 
Chondrin,  398 
ChonUrus  crispus,  358 
Chromate  of  barium,  88 
calcium,  98 
lead,  189 
mercury,  212 

potassium  and  ammonium,  89 
potassium,  standard  solution 
of  red,  491 
silver,  187 
Chromates,  211 

analytical  reactions  of,  211 
of  potassium,  88,  106,  210 
Chrome-alum,  117 
-ironstone,  210 
-red,  189 
-yellow,  189 
Chromic  acid,  211 
anhydride,  211 
hydrate,  212 
salts,  210 
Chromium,  210 

analytical  reactions  of,  212 
chloride  of,  211 
derivation  of  word,  30 
separation  of,  from  aluminium 
and  iron,  213 
sulphate  of,  211 
Chromous  salts,  210 
Chromule,  416 
Chrysophanic  acid,  300 
Chrysammic  acid,  393 
Chrysorhamnin,  415 
Cicutine,  351 


CincJioim  Jlavce  cortex^  343 
pallidce  cortex^  343 
rubrce  cortex^  343 
Cinchonia,  346 
CinchonicB  sulphas^  346 
Cinclionicia,  346 
Cinchonicine,  346 
Cinchonidia,  346 
Cinchonidine,  346 
£!inchonine,  346 
Cinnabar,  170 
Cinnamein,  413 
Cinnamic  acid,  413 
alcohol,  413 
Cinnamomi  cortex,  407 
Cinnamon  oil,  407 
Cinnamyl,  hydride  of,  413 
Cissampelia,  351 
Cissampeline,  351 
Cissarnpelos  pareira,  351 
Citrate  of  ammonium,  79 
calcium,  291 
iron,  130 

iron  and  strychnia,  130 
iron  and  quinine,  131,  344, 
582 

lithium,  200 
magnesium,  289 
nicotia,  352 
potassium,  60 

volumetric  estimation  of, 
481 

quinine,  344 
silver,  291 
Citrates,  60,  289 

analytical  reactions  of,  290 
volumetric  estimation  of,  478, 
481 

Citric  acid,  289 

action  of  heat  on,  291 
saturating  power  of,  290,  549 
Citronella  oil,  407 
Citronellol,  407 
Citro-tartarate  of  sodium,  73 
Classification  of  elements,  86,  105, 
107,  230 

Claviceps  purpurea,  411 
Clay,  116,  214 

ironstone,  119 
Cloves,  oil  of,  407 
Club-moss,  403 
Coal,  213 

products  of,  382 
-gas,  382 


INDEX 


569 


Coal-gas — 

for  balloons,  21 
-tar  colors,  417 
Cobalt,  207 

analytical  reactions  of,  207 
arsenide  of,  207 
blue,  416 

derivation  of  word,  30 
-glance,  207 
hydrate  of,  207 
separation  of,  from  nickel 
209 

sulphate  of,  207 
sulphide  of,  207 
Cobaltic  ultramarine,  416 
Cobalticyanide  of  potasium,  208 
of  nickel,  209 
Cobalticyanides,  208 
Coccus^  300 
Ilicis,  158 
Cochineal,  300 
Cocoa,  402 
Cocoa-butter,  402 
Cocoa  nibs,  402 
Cocoa-nut,  402 
Cocoa-nut  oil,  402 
Cocos  nucifera,  402 
Codamine,  341 
Codeia,  342 
Cod-liver  oil,  402 
Coinage,  copper,  167,  467 
gold,  217,  467 
silver,  191,  467 
Coke,  26 

Colchici  cormuSf  354 
semina,  354 
Colchicia,  354 
Colchicine,  354 
Colchicum  vinegar,  265 
Colcothar,  415 
Collection  of  gases,  16, 17 
Collin,  537 
Collodion,  360 
Collodium,  360 
flexile,  360 
Colloid  bodies,  537 
Colocynthidis  pulpa,  367 
Colocynthin,  367 
Colopholic  acid,  410 
Colophonic  acid,  410 
hydrate,  410 
Colophonine,  411 
Colophony,  410 
Coloring-matters,  414 


Combination,  chemical,  38,  ^0 
by  volume,  44 

Combining  proportions,  42,  173, 
257,  445,  497 
Combustible,  21 
Combustion,  21 

analysis  for  carbon  and  hy- 
drogen, 525  et  seq. 
for  nitrogen,  525,  527 
definition  of,  48 
supporters  of,  21 
Composition  of  atmosphere,  24 
bismuth  salts,  225 
oils  and  fats,  400 
Compound,  chemical,  27 

difi’erent  from  mechani- 
cal, 32 

definition  of,  50 
Compounds,  13,  32 

of  the  elements,  51 
Condensation,  108 
Condenser,  108 
Condensing  tub,  108 
worm,  108 

Condy’s  disinfecting  fluids,  64,  205 
Confections,  442 
Conia,  conine,  or  oonicine,  351 
Conii  folia,  352 
fructus,  352 

Conium  maculatum,  352 
Constant  proportions,  law  of,  42 
Construction  of  formulae,  36,  47, 
54,  360 

Constitution  of  alkaloids,  338 
of  salts,  44.  104,  235,  253, 
267 

of  visible  matter,  33 
Convolvulin,  369 
Convolvulinol,  369 
Convolvulus  scammonia,  371 
Conylia,  352 
Copaiba,  411 

impurities  in,  411,  543 
Copaiva,  411 
oil,  411 

Copaivic  acid,  411 
Copper,  166 

acetate  of,  168 

ammonio-sulphate  of,  153, 
169,  182 

analytical  reactions  of,  168, 
420 

antidotes  to,  170 
arseniate  of,  153 


48* 


570 


INDEX. 


Copper — 

arsenical,  149 

arsenite  of,  153 

black  oxide  of,  167 

blue,  416 

coinage,  167,  467 

derivation  of  word,  29 

detection  of  arsenicum  in,  149 

foil,  167 

hydrate  of,  169 

iodide  of,  245 

in  organic  mixtures,  detection 
of,  420 

melting-point  of,  416 
metallic,  167 
oxide  of,  167 
oxyacetate  of,  168 
pyrites,  166, 

quantitative  estimation  of, 
509 

quantivalence  of,  167 
subacetate  of,  168 
sulphate  of,  168 
sulphate  of  anhydrous,  168 
sulphide  of,  168 
Copperas,  blue,  121 
green,  121 
Coptis  trifolia,  351 
Coriander  oil,  407 
Coriandri  fructiis,  407 
Coriandrum,  407 
Cork-borers,  16 

Correction  of  the  volume  of  a gas 
for  pressure,  469 
for  temperature,  469 
Corrosive  sublimate,  172,  176 
test  for  in  calomel,  178 
Cotton-wool,  359 
Cows’  milk,  397 
Cream,  397 
Cream  of  tartar,  285 
Creasol,  392 
Creasote,  392 
Creasotum,  392 

impurities  in,  543 
Cresol,  392 
Ciesylic  acid,  392 
Creta,  94 

prceparata,  94 
Crocus  (mineral),  129 
(vegetable),  415 
Crocus  salivas,  415 
Croton  oil,  403 
Crotonate  of  glyceryl,  403 


Crucibles,  57 
Crude  antimony,  155 
potashes,  54 

Crum’s  test  for  manganese,  207 

Cryolite,  334 

Cryptophanic  acid,  429 

Cryptopia,  341 

Crystallization,  water  of,  70 

Crystalloid  bodies,  537 

Cubeba,  353 

Cubeb  pepper,  353 

Cubebs,  oil  of,  407 

Cubic  inches  in  1 gallon,  431 

Cubic  nitre,  252 

Cudbear,  416 

Cupel,  513 

Cupellation,  estimation  of  silver 
by,  513 

Cupr-diammon-diammonium,  sul- 
phate of,  182 
Capri  subacetas,  168 
sulphas,  168 

sulphas,  impurities  in,  543 
Cupric  arsenite,  153,  169 
compounds,  168 
ferrocyanide,  169 
hydrate,  169 
oxide,  167 
sulphate,  168 
sulphide,  168 
Cuprous  iodide,  168,  246 
oxide,  168,  361 
Cuprum,  29,  156 

ammonialurn,  169 
Curcuma  longa,  415 
Curcumin,  415 
Curds,  362,  397 

and  whey,  362,  397 
Caspar  ice  cortex,  355 
Cusparin,  355 
Casso,  411 
Cyanates,  300 
Cyanic  acid,  300 
Cyanide  of  mercury,  248 
nickel,  209 
potassium,  248 
silver,  194 
Cyanides,  247 

analytical  reactions  of  metal- 
lic, 250 

antidote  to,  251 
double,  248 

quantitative  estimation  of, 
486 


INDEX. 


5n 


Cyanogen,  247,  515 
Cyanurets,  vide  Cyanides 
Cy still,  433 

Dalton’s  atomic  theory,  43 
Daphne  laureola,  411 
mezereuin,  411, 

Daturia  or  datiirine,  350 
Dauglisli’s  bread,  362 
Davy’s  safety-lamp,  21 
Deadly  nightshade,  350 
Decantation,  93 
Decimal  coinage,  455 
weights,  454,  457 
Decoctions,  442 
Decrepitation,  330 
Decolorizing  power  of  animal 
charcoal,  95 

Definition  of  chemical  action,  32 
a chemical  compound,  48 
a chemical  equation  or  dia- 
gram, 49 

a chemical  symbol,  49 
a gas,  49 
a liquid,  49 
a mixture,  48 
an  atom,  48 
an  element,  48 
a solid,  49 
atomic  weights,  50 
chemical  force,  48 
chemistry,  48 
combustion,  48 
law  of  dififusion,  49 
molecular  weights,  50 
quantivalence  of  atoms,  50 
Deflagrating  flux,  335 
Deflagration,  62 
Deliquescence,  73 
Density,  464 

of  vapors,  470 
Deodorizers,  25 
Deodorizing  liquid.  111 
Deposits,  urinary,  432 
Derivation  of  names  of  elements, 
27  et  seq. 

Derivatives  of  ammonium,  182 
Desiccation,  498,  500,  519 
Destructive  distillation,  109 
Detonation,  62 
De  Valangin’s  solution,  145 
De  Vry’s  process  for  estimating 
the  purity  of  commercial  qui- 
nine, 529 


Dextrine,  357 
Dextroracemic  acid,  285 
Dextrose,  363 
Dextrotartaric  acid,  285 
Diabetic  urine,  362,  430,  534 
Diagram,  chemical,  definition  of, 
49 

Diagrams,  chemical,  38,  54 
Dialysis,  537 
Diamines,  339 
Diamond,  26 
Dibasic  acids,  337 
Dibasylous  radicals,  337 
Didymium,  551 
Diethylamine,  339 
Diethylia,  339 
Diffusion,  22 

law  of,  definition  of,  49 
Digitalin,  367 
Digitalinum,  367 
Digitaliretin,  368 
Digitalis  folia^  368 
Dill  oil,  406 
Dinitrocellulin,  359 
Dipterocarpus  tnrhinatus,  412 
Disinfectant,  chlorine  as  a,  25 
Disinfectants,  25 
Disinfecting  fluid,  Burnett’s,  111 
carbolic  acid,  391 
Condy’s,  64,  205 
powder,  96 
Distillation,  108 

destructive,  109 
dry,  109 
fractional,  372 
Distilled  vinegar,  2i35 
Dithionic  acid,  307 
Dolomite,  99 
Donovan’s  solution,  174 
Dorema  ainmoniacMin,  412 
Double  chloride  of  aluminium 
and  sodium,  116 
cyanides,  248 
salts,  65 

Dover’s  powder,  352 
Drachm,  460 
Draconyl,  413 
Dried  alum,  117 
Drugs,  15 

Dry  distillation,  109 
Drying  apparatus,  498,  500,  519 
oils,  402 

precipitates,  498,  500,  503, 
519 


572 


INDEX. 


Dryobalanops  aromatlca^  409 
Dulcamara,  353 
Dyads,  104 
Dyers’  saffron,  415 
Dyeing,  117,  258 
by  mordants,  117 
Dynamic  electricity,  production 
of,  110 

Dynamicity,  47 

Earth,  bone-,  94 
Earthenware,  314 
Earths,  alkaline,  108 
Eau  de  Cologne,  406 
Ebonite,  414 
Echallii fructus,  349 
“Effervescing  citrate  of  magne- 
sia,” 289 

citro-tartrate  of  sodium,  73 
potash-water,  59,  500 
soda-water,  71 
Efflorescence,  73 
Egg,  white  of,  396 
yolk  of,  396 
Elseometer,  466 
Elseoptens,  405 
Elaterin,  859 
Elateriuin,  359 

impurities  in,  543 
Elder-flower  oih  408 
Electricity,  production  of  dyna- 
mic, 110 

Elementary  particles,  33 
Element,  definition  of,  48 
Elements,  13,  14,  27 

and  their  compounds,  51 
classification  of,  86,  104,  107, 
230 

classification  of  according  to 
analogy,  86 

classification  of  according  to 
quantivalence,  104 
etymology  of  names  of,  27 
of  medical  or  pharmaceutical 
interest,  14 
metallic,  15 
non-metallic,  15 
of  pharmaceutical  interest,  14 
symbols  of,  27,  37 
symbols,  atomic  values,  and 
weights  of  the,  551 
symbols  of,  and  derivation  of 
names  of,  27  et  scq. 

Elemi,  412 


Elm  bark,  318 
Emetia,  352 
Emetine,  382 
Empirical  formulae,  373 
Emplastra,  411 

Emplastrum  ceraii  saponis,  265 
plumhi,  188 
plumbi  iodidi,  188 
Emulsin,  366,  393 
Emulsion,  413 
Enemas,  442 
English  red,  415 
blue,  416 
Epsom  salt,  100 

Equation,  chemical,  definition  of, 
49 

Equations,  40 
Equivalence,  44 
Equivalents,  551 
Equisetic  acid,  295 
Ergot,  411 
Ergota,  411 
Ergotin,  411 
Erlangen  blue,  416 
Erythroretine,  300 
Erucic  acid,  404 
Eseria,  353 

Essence  of  aniseed,  405 
apple,  389 
greengage,  390 
melon,  390 
mirbane,  391 
mulberry,  390 
pineapple,  390 
quince,  390 
peppermint,  406 
Essences,  405 
Essentia  anisi,  405 

menthce  piperitce,  406 
Essential  oils,  vide  Oils. 
Estimation  of  weight,  452 
Etching,  304 
Ethal,  402 
Ether,  376 

nitrous,  378 
Ethereal  salts,  381 
oil,  394 
Etherol,  394 
Ethers,  381 
Ethiops  mineral,  182 
Ethyl,  374,  380 
acetate  of,  374 
butyrate  of,  389 
hydrate  of,  374 


INDEX. 


573 


Ethyl- 

hydride  of,  380 
iodide  of,  380 
nitrite  of,  278 
oenanthylate  of,  390 
oxide  of,  374 
pelargonate  of,  390 
sebacate  of,  390 
suberate  of,  390 
sulphate  of,  374 
zinc,  380 
Ethylamine,  339 
Ethylene,  394 
Ethylia,  339 
Ethylic  alcohol,  374 
Etymology  of  names  of  elements, 
28 

Eucalyptol,  407 
Eucalyptus  globulus^  407 
Euchlorine,  263 
Eudiometry,  336 
Eugenic  acid,  407 
Engeiiin,  407 
Euodic  aldehyd,  408 
Euxanthate  of  magnesium,  415 
Evaporation,  58,  86,  498,  500 
in  vacuo ^ 500 
Everitt’s  yellow  salt,  249 
Examinations  of  the  Pharmaceuti- 
cal Society  of  Great  Britain,  41 
{vide  Prefatory  matter). 
Expansion  on  diluting  solution  of 
ammonia,  77 
Explosions  of  gases,  20 
Extracts,  442 
Extr actum  cannabis^  411 
filicis  liquidum^  403 
Saturnij  187 

Face-rouge,  300,  416 
Faeces,  429 

Fahrenheit's  thermometer,  448 
Farina  tritici,  356 
Fat-acids,  404 

Fats  and  oils,  composition  of,  400 
Fats,  etc.,  to  determine  the  melt- 
ing-point of,  450 
analysis  of,  539 
Fatty  bodies,  400 
Eel  bovinum  purijicatum,  401 

purijicatum,  impurities  in,  543 
Felspar,  335 
Fennel  oil,  407 
Fermentation,  362 


Fermentum,  372 
Fer  reduit^  135 
Ferrate  of  potassium,  120 
Ferri  acetis  tinctura,  127 
arsenias,  123 

arsenias,  impurities  in,  543 
carbonas,  122 
carbonas  saccharata^  122 
carbonas  saccharata,  impuri- 
ties in,  543 
citras,  130 

et  ammonice  citras,  131 
et  ammonice  citras,  impurities 
in,  543 

et  ammonice  citras^  quantita- 
tive estimation  of  iron  in, 
507 

et  ammonice  sulphas^  117 
et  ammonice  tartras,  133 
et  potassce  tartras,  133,  288 
et  quince  citras,  131 
et  quinice  citras,  impurities  in, 
543 

et  strychnice  citras,  133 
ferrocyanidum,  303 
hypophosphis,  306 
iodidum,  27,  184 
lactus,  309 
oxalas,  282 

oxidum  magneticum,  133 
oxidum  maqneticum,  impurities 
in,  544 

perchloridi,  liquor,  126 
pernitratis,  liquor,  135 
per  oxidum  liumidum,  129 
peroxidum  hydratum,  128 
peroxidum  hydratum,  impuri- 
ties in,  544 

persulphatis,  liquor,  127 
phosphas,  120 

phosphas,  impurities  in,  544 
potassio- tartras,  130 
j)ulvis,  135 
pyropliosplios,  136 
subcarbonas,  122 
sulphas,  121 

sulphas,  impurities  in,  544 
sulphas  exsiccata,  121 
sulphas  granulata,  121 
sulphas  granulata,  impurities 
in,  544 

sulphur  etum,  124 
Ferric  acetate,  127 
chloride,  125 


574 


INDEX. 


Ferric — 

hydrate,  128 
hypophosphite,  306 
iodate,  264 
nitrate,  134 
oxide,  129 

oxide,  from  phosphates  and 
oxalates,  separation  of,  333 
oxyiodate,  264 
oxysulphate,  122 
peroxyhydrate,  128 
pyrophosphate,  136 
salts,  125 

salts,  analytical  reactions  of, 
- 136 

sulphate,  127 
sulphocyanate,  138 
Ferridcyanide  of  potassium,  137., 
303 

Ferridcyanides,  303 
Ferridcyanogen,  138,  303 
Ferrocyanide  of  potassium,  248 
802 

of  zinc,  114 
Ferrocyanides,  303 
Ferrocyanogen,  138,  302 
Ferro-ferric  hydrate,  133 
oxide,  133 

Ferrous  arseniate,  123,  492 
bromide,  124 
carbonate,  1 22,  492 
chloride,  126 
iodide,  124 
phosphate,  123 
salts,  121 

salts,  analytical  reactions  of, 
136 

sulphate,  121 
sulphide,  124,  136,  137 
Ferriim,  29,  119 
redacturn,  135 
taj'taratum,  133,  288 
tartaratum,  estimation  of  iron 
in,  507 

tartaratum,  impurities  in,  544 
Fibrin,  396 

vegetable,  398 
FicuSj  362 

elasiica,  413 
Fig,  362 
Filix  mas,  403 
Filter,  to  dry,  498 
Filtering-paper,  93,  497 
Filters,  93,  497 


Filtrate,  106 
Fine  gold,  218 
Fire-clay,  177 
Fire-damp,  382 

Fixed  and  volatile  oils,  difference 
between,  405 
oils,  400 

Flame,  oxidizing,  331 
reducing,  331 
structure  of,  21 
Flare,  401 
Flaxseed,  402 

Fleitmann’s  test  for  arsenicum, 
150 

Flexible  collodion.  360 
Flint,  314 
Flores  zinci,  113 
Flour,  355 

Flowers  of  sulphur,  269 
Fluid  magnesia,  101 
Fluoric  acid,  304 
Fluoride  of  boron,  297 
calcium,  90 

calcium,  in  bones,  94,  304 
silicon,  305 
Fluorides,  304 
Fluorine,  305 

derivation  of  word,  30 
Fluor-spar,  304 
Foeniculi fructus,  407 
Foil,  copper,  167 
Food,  analysis  of,  539 
elements  of,  398 
how  disposed  of  in  the  bodies 
of  animals,  429 
Force,  chemical,  34 
Forge-scales,  134 
Formates,  301 
Formic  acid,  301,  401 
Formica  rufa,  301 
Formula,  chemical,  definition  of, 
49 

ofllcial,  25 
officinal,  25 
Formulae,  39,  40,  528 

construction  of,  47,  53 
empirical,  373,  528 
graphic,  115 
rational,  373,  528 
Fousel  oil,  3S9 
Fowler’s  solution,  144 
Foxglove,  367 
Fraxinus  orniis,  361 
Fractional  distillation,  371 


INDEX. 


575 


Frankincense,  412 
Frankland’s  graphic  formulae,  115 
Freezing-mixture,  272 
French  chalk,  417 
turpentine,  407 
Fruit  essences,  389 
Fuchsine,  417 
Fume-cupboard,  81 
Fuming  sulphuric  acid,  277 
Funnel-tubes,  81 
“Fur”  in  water  vessels,  281 
Furniture  of  a laboratoiy,  xii. 
Fusel  oil,  389 

Fusibility  of  metals,  table  of  the, 
451 

Fusible  white  precipitate,  181 
Fusing-points  of  fats,  451 
Fustic,  414 

Galactometer,  466 
Galhanum,  412 
Galena,  185 

argentiferous,  191 
Galenical  preparations  of  the  Bri- 
tish Pharmacopoeia,  442 
Galipot,  410 
Galla,  317 
Gallic  acid,  318 
Gall  of  the  ox,  401 
Gallon,  460 
Galls,  Aleppo,  317 
English,  317 
Gall-stones,  441 
Galvanic  test  for  mercury,  183 
Galvanized  iron,  109 
Gambir,  318 
Gamboge,  412,  414 
Gambogic  acid,  412 
Garancin,  415 
Garcinia  morella,  412 
Garlic,  essential  oil  of,  393 
Gas-analysis,  319,  336 
a,  definition  of,  49 
-burners,  16,  17,  21 
for  balloons,  coal-,  21 
illuminating,  368 
-lamp,  17,  21 

Gases  and  vapors,  density  of,  447, 
469 

collection  of,  16,  17 
correction  of  the  volume  of, 
469 

for  pressure,  469 
for  temperature,  469 


Gases  and  vapors — 
diffusion  of,  22 
law  of  solubility  of,  in  liquids, 
71 

relation  of,  to  liquids  and 
solids,  38 

specific  gravity  of,  469 
Gastric  juice,  399 
artificial,  399 

Gaultheria  procumbensy  390 
Gaultheric  acid,  390 
Gelatine,  398 

vegetable,  358 
Gelatinous  substances,  398 
Gentiance  radix,  355 
German  silver,  208 
Ginger  oil,  408 

Girdwood  and  Rogers’s  method  for 
detecting  strychnia,  424 
Glacial  acetic  acid,  266, .451 
phosphoric  acid,  294 
Glass,  314 

liquor,  315 
rods,  93 
soluble,  315 
tubes,  to  bend,  16 
to  cut,  16 
to  draw  out,  93 
Globulin,  396 
Glucinum,  551 
Glucose,  362 
Glucosides,  365 
Glue,  398 

Gluten  and  glutin,  356 
Glyceric  alcohol,  394 
Glycerine,  394,  188 
Glycerines,  394 
Glycerina,  394 

impurities  in,  544 
Glyceritum  acidi  carholici,  395 
acidi  gallici,  395 
acidi  tannici,  317,  395 
picis  liquidce,  395 
sodii  horatis,  395 
Glyceryl,  394,  400 
caproate  of,  402 
caprylate  of,  402 
crotonate  of,  403 
hydrate  of,  394,  400 
laurate  of,  402 
margarate  of,  402 
myristate  of,  402 
oleate  of,  400 
palmitate  of,  402 


676 


INDEX 


Glyceryl — 

ricinoleate  of,  403 
rutate  of,  402 
tristearate  of,  400 
Glycholates,  401 
Glycocine,  401 
Glycocoll,  401 
Glycol,  394 
Glycols,  394 
Glycyl,  394 
Glycyrrhizce  radix,  364 
Glycyrrhizin,  364 
Gold,  216 

analytical  reactions  of,  218 
coin,  217,  467 
derivation  of  word,  31 
earth,  216 
fine,  218 
jewellers’,  217 
leaf,  217 
mosaic,  216 
ochre,  414 
perchloride  of,  217 
sulphide  of,  218 
yellow,  414 
Goldthread,  351 
Gossypium,  359 
Gothite,  129 
Goulard’s  cerate,  187 
extract,  187 
water,  1S7 

Graham’s  dialytic  process,  537 
law  of  diffusion,  22 
Grain,  453 
Grains,  453 
Gramme,  455 

relation  of,  to  grains,  457,4 
Granati fructus  cortex,  318 
radicis  cortex,  318 
Granite,  116 
Granulated  tin,  214 
phosphorus,  293 
zinc,  19 

Grape-sugar,  361 
Graphic  formulae,  115 
Graphite,  26 
Gravel,  432 

Gravimetric  analysis,  446,  497 
Gravitation,  452 
Gravity,  452 
Gray  powder,  171 
Green  copperas,  121 

chloride  of  iron,  125 
iodide  of  iron,  124 


Green — 

iodide  of  mercury,  173 
pigments,  416 
sulphate  of  iron,  121 
vitriol,  1 21 

Greengage  essence,  390 
Griffitli’s  mixture,  123 
Group  tests,  231 
Guaiaci  lignum,  369 
resina,  369 
Guaiacin,  369 
Guaiacol,  392 
Guaiacum,  resin  of,  369 
Guaiaretin,  369 
Guaiaretinic  acid,  369 
Guano,  320 
Guarana,  353 
Gum,  358 

-acacia,  97,  357 
-arable,  97,  357 
British,  357 
cherry-tree,  358 
-resins,  412 
tragacanth,  358 
Gummate  of  calcium,  97,  357 
lead,  97 

Gummic  acid,  357 
Gun-cotton,  359 
Gun  metal,  213 
Gunpowder,  258 
Gutta  percha,  413 
Gypsum,  90 

Hgematin,  396 
Haematite,  brown,  119 
red,  119 

Hcematoxyli  lignum,  318,  416 
Haematoxylin,  318,  416 
Half-sovereign,  weight  of  the,  217 
Haloid  salts,  254 
Hambro’  blue,  416 
Hardness  of  water,  281 
Hard  soap,  400 
Heat,  latent,  71 
source  of,  16 

Heavy  carbonate  of  magnesium, 

lor 

magnesia,  102 
spar,  87 
white,  87,  417 
Heberden’s  ink,  138 
Hectare,  455 
Hellebore,  354 
Hemidesmi  radix,  301 


INDEX. 


5n 


Hemidesmic  acid,  301 
Hemlock,  352 
Hempseed  calculi,  441 
Henbane,  352 
Hesperidene,  406 
Hevea  siphonia  Braziliensis^  413 
Heterologous  series,  382 
Hexyl,  381 

Hippuric  acid,  301,  433,  436 
Hips,  363 

Hoflfner’s  blue,  416 
Homologous  series,  382,  404 
Honey,  363 
dew,  364 
Hop,  412 

essential  oil  of,  412 
Ilordeum  decor  tic  alum  ^ 356 
Horeliound,  vide  Marrubium 
Horsemint,  409 
Horseradish  oil,  382,  406 
Hubbuck’s  oxide  of  zinc,  113 
Humulus  lupulus,  412 
Hydrargyri  chloridum  corrosivinn, 
176 

chloridum  mite^  177 
cyanidum^  248 
iodidum  ruhrum,  174 
iodidum  ruhrum^  impurities 
in,  544 

iodidum  viride,  172 
iodidum  viride,  impurities  in, 
544 

nitrati  acidus  liquor,  175 
nitratis  liquor,  175 
oxidum  Jlavum,  179 
oxidum  ruhrum,  178 
oxidum  ruhrum,  impurities  in, 
544 

perchloridum,  176 
suhchloridum,  177 
suhchloridum,  impurities  in, 
544 

sulphas,  175 
sulphas  Jiava,  176 
sulphas,  impurities  in,  544 
sulphuretum  cum  sulphure,  182 
sulphuretum  cum  sulphure,  im- 
purities in,  544 
sulphuretum  ruhrum,  182 
unguentum,  171 
Hydrargyrum,  29,  170 
impurities  in,  544 
ammoniatum,  181 
ammoniatum,  impurities  in,544 
49 


Hydrargyrum — 
cum  creta,  171 

cum  creta,  impurities  in,  544 
Hydrated  peroxide  of  iron,  129 
substances,  70 
Hydrate  of  aluminium,  117 
ammonium,  76 
benzoyl,  299 
cadmium,  222 
calcium,  92 
cetyl,  402 
chromium,  212 
cobalt,  207 
glyceryl,  402 
manganese,  206 
nickel,  209 
potassium,  53 
sodium,  68 
zinc,  114 

Hydrates,  composition  of,  54,  70 
Hydraulic  cement,  314 
Hydric  acetate,  chloride,  nitrate, 
sulphate,  etc.,  vide  the  respec- 
tive acids — acetic,  hydrochloric, 
etc. 

Hydride  of  antimony,  160 
arsenicum,  149 
benzoyl,  366,  413 
cinnamyl,  413 
copper,  307 
ethyl,  382 
methyl,  382 
phosphorus,  306 
silicon,  315 
Hydrides,  105,  382 
Hydriodic  acid,  243 
Hydrium,  19 
Hydrobromic  acid,  241 
Hydrocarbons,  405 
Hydrochlorate  of  morphia,  340 
Hydrochloric  acid,  26,  238 

acid,  analytical  reactions  of, 
240 

acid,  antidote  to,  241 
acid,  common,  238 
dilute,  238 

acid  in  organic  mixtures,  de- 
tection of,  418,  421 
acid,  volumetric  estimation 
of,  484 

Hydrocotarnine,  341 
Hydrocyanic  acid,  247 

acid,  analytical  reactions  of, 
250,  421 


578 


INDEX. 


Hydrocyanic—  - 

acid,  antidotes  to,  251 
acid,  dilute  249 
acid  from  bitter  almond  and 
cherry -laurel,  366 
acid  in  organic  mixtures,  de- 
tection of,  421 
acid  in  the  blood,  251 
acid,  Schonbein’s  test  for,  252 
acid,  volumetric  estimation 
of,  486 

Hydroferridcyanic  acid,  303 
Hydroferrocyanic  acid,  302 
Hydrofluoric  acid,  304 
Hydrogen,  18 

antimoniiiretted,  160 
arseniuretted,  149 
benzoate,  borate,  etc.,  vide  the 
respective  acids,  benzoic, 
boracic,  etc. 
combustion  of,  19 
derivation  of  word,  28 
explosion  of,  20 
functions  of,  104 
in  artificial  light-producers, 
21 

lightness  of,  21 
peroxide  of,  88 
persulphide  of,  271 
phosphoretted,  305 
preparation  of,  19 
properties  of,  19 
quantitative  estimation  of,  in 
organic  compounds,  525  et 
seq. 

salts  of,  235 
siliciuretted,  316 
sulphuVetted,  81,  270 
used  for  balloons,  21 
weight  compared  with  air,  22 
weight  of  1 litre,  470 
weight  of  100  cubic  inches, 
470 

Ifydrogenium,  19 
Hydrometers,  466 
Hydrosulphuric  acid,  270 
Hydrosulphyl,  270 
Hydrous  chloral,  387 
Hydrous  compounds,  70,  102 
Hydroxyl,  270 
Hygiene,  14 
Hyoscyamia,  352 
II goscy  ami  folia  ^ 352 

semen^  352  I 


Hyoscyamine,  352 
Hyper-,  meaning  of,  125 
Hypo-,  meaning  of,  308 
Hypobromites,  242 
Hypochloride  of  sulphur,  272 
Hypochlorite  of  calcium,  96 
sodium,  72 
Hypochlorites,  260 
Hypochlorous  acid,  260 
Hypophosphite  of  iron,  306 
of  potassium,  306 
Hypophosphites,  305 
Hypophosphorous  acid,  305 
Hyposulphite  of  calcium,  305  ' 

sodium,  307 

sodium,  standard  solution  of, 
493 

Hyposulphites,  307 
Hyposulphurous  acid,  307 

-ic,  meaning  of,  63, 120 

Iceland  moss,  300 

Icthyocolla^  398 

-ide,  meaning  of,  63 

Igasuria,"348 

Ignatia,  347 

Ignition,  86 

Illicium  anisatum^  406 

Illuminating  agents,  analysis  of, 

Inch, 460 
Incineration,  86 

of  filters  in  quantitative  ana- 
lysis, 497,  503 
Indelible  ink,  193 
Indian  hemp,  411 
ink,  417 
red,  415 
rubber,  413 

rubber,  vulcanized,  414 
yellow,  415 
Indican,  258 
Indiglucin,  258 
Indigo,  258 

sulphate  of,  258 
-blue,  258 
-white,  258 
Indigogen,  258 
Indigotin,  258 
Indium,  551 

Infusible  white  precipitate,  182 
Infusions,  442 
Inhalation  of  chlorine,  25 
coniue,  352 


INDEX. 


579 


Inhalation  of — 

hydrocyanic  acid,  249 
Inhalations,  442 
Ink,  black,  138,  318 
Heherden’s,  138 
indelible,  193 
Indian,  417 
invisible,  208 
marking,  193 
printer’s,  417 
sympathetic,  208 
Inorganic  chemistry,  338 
compounds,  338 
Introduction,  13 
Inverted  sugar,  363 
lodate  of  potassium,  61,  263 
lodates,  263 
Iodic  acid,  263 
Iodide  of  arsenicum,  143 
cadmium,  221 
ethyl,  380 
hydrogen,  243 
iron,  27,  124 
lead,  188 
potassium,  61 
silver,  194 
sulphur,  244 
Iodides,  243 

analytical  reactions  of,  244 
of  mercury,  172,  181 
quantitative  estimation  of, 
514 

separation  of,  from  bromides 
and  chlorides,  246 
Iodine,  27,  243 
chloride  of,  244 
derivation  of  word,  28 
its  analogy  to  chlorine  and 
bromine,  243 
solution  of,  244 
standard  solution  of,  488 
tincture  of,  244 
volumetric  estimation  of,  493 
-water,  244 
Iodoform,  374,  386 
lodum,  243 

impurities  in,  544 
lodinium,  243 
Ipecacuanha,  352 
Ipomoea  turpethum,  176 
Iridium,  221,  551 
Iris  Jlorenlina,  407 
Irish  moss,  358 
Iron,  119 


Iron — 

acetate  of,  127 
alum,  117 

ammonio-citrate  of,  131 
amrnonio-tartrate  of,  133 
analytical  reactions  of,  136 
arseniate,  123,  147 
arseniate  of,  volumetric  esti- 
mation of,  492 
black  hydrate  of,  133 
black  oxide  of,  134 
bromide  of,  124 
carbonate  of,  122,  492 
cast,  119 
chlorides  of,  125 
compounds,  nomenclature  of, 
120 

derivation  of  word,  29 
detection  of,  in  presence  of 
aluminium  and  zinc,  138 
galvanized,  109 
hydrated  peroxide  of,  128 
hypophosphite  of,  306 
in  official  compounds,  estima- 
tion of,  492,  507 
iodate  of,  264 
iodide  of,  27,  124 
lactate  of,  309 
magnetic  oxide  of,  133 
magnetic  oxide  of,  estimation 
of  iron  in,  492 
nitrate  of,  134 
ore,  magnetic,  119 
ore,  needle,  129 
ore,  spathic,  119 
ore,  specular,  119 
oxide  of,  134 
oxy hydrates  of,  129 
oxysulphate  of,  122 
perchloride  of,  125 
perhydrate  of,  128 
pernitrate  of,  135 
peroxide  of,  129 
peroxyhydrate  of,  129 
persulphate,  of  127 
phosphate  of,  123 
phosphate  of,  volumetric  esti- 
mation of,  492 

from  phosphates  and  oxa- 
lates, separation  of  per- 
oxide of,  332 
potassio-citrate  of,  130 
potassio-tartrate  of,  133 
pyrites,  119 


580 


INDEX. 


Iron- 

pyrophosphate,  136 
quantitative  estimation  of, 
492,  507 

and  quinine,  citrate  of,  131, 
344,  532 

red  oxide  of,  129 
reduced,  135 
rust  of,  119 

saccharated  carbonate  of,  122 
saccharated  carbonate  of,  vo- 
lumetric estimation  of,  492 
salts,  nomenclature  of,  120 
scale  compounds  of,  130 
separation  of,  from  alumin- 
ium and  chromium,  213 
sodio-citrate  of,  130 
sodio-tartrate  of,  130 
-stone,  clay,  119 
suhcarbonate,  122 
subsulphate,  127 
sulphate  of,  121 
sulphide  of,  124 
sulphocyanateof,  130,138,251 
tersulphate  of,  127 
wrought,  119 
Isinglass,  398 
Isomerism,  358 

Isomorphism,  the  doctrine  of,  46 
Isoraorphous  bodies,  46,  295 
Isonandra  gutta^  414 
-ite,  meaning  of,  60 
Ivory-black,  417 

Jalap  resin,  369 
Jalapa^  369 
Jalapce  resina,  369 

resina,  impurities  in,  544 
Jalapic  acid,  369 
Jalapin,  369 
Jalapinol,  369 
Jaune  hrillant,  222 
Jelly,  398 

vegetable,  358 
Jervia,  354 
Jervine,  354 
Juices,  442 
Juniper-oil,  407 
Juniperus,  407 

Kalium,  28 
Kamala^  411 
Kelp,  243 

Kermes,  mineral,  158 


Kilbride  mineral,  129 
Kiln,  91 

Kilogram,  456,  457 
Kilolitre,  462 
Kilometre,  456 
Kinate  of  quinia,  343 
King’s  blue,  416 
Kino,  318 
Kola-nut,  353 
Kousso,  411 
Kramer  ice  radix  ^ 318 

Laboratory  furniture,  x. 

Lac,  397 
Lac-dye,  416 
Lactates,  309 
Lactic  acid,  309 
Lactometer,  397 
Lactose,  362 
Latuca,  355 
Lactucin,  355 
Lsevogyrate,  363 
Lsevoracemic  acid,  285 
Lsevorotation,  363 
Laevotartaric  acid,  285 
Lsevulose,  363 
Lakes,  118 
Lampblack,  417 
Lamps,  gas-,  16,  21 
Lana  philosophica,  114 
Lanthanium,  551 
Lard,  401 

benzoated,  401 
prepared,  401 
Larix  europcea,  408 
Latent  heat,  71 
Laudanine,  341 
Laudanosine,  341 
Laughing-gas,  257 
Laurate  of  glyceryl,  402 
Laurel-camphor,  409 
Laurie  aldehyd,  408 
Laurie  acid,  404 
Laurocerasi  folia,  366 
Lavender-oil,  407 
-water,  406 
Lavender,  oil  of,  407 
Law,  Avogadro’s  and  Ampere’s, 
44,  45 

of  chemical  combination  by 
weight,  40  et  seq.,  49 
by  volume,  44  et  seq.,  49 
concerning  molecular  weight, 
46,  237,  471 


INDEX. 


581 


Law — 

of  constant  proportions,  41, 
445,  497 

of  diffusion,  definition  of,  49 
multiple  proportions,  42,  176, 
257 

reciprocal  proportions,  41 
solubility  of  gases  in  liquids, 
71 

Laws  of  chemical  combination, 
40,  44,  49 
Lead,  185 

acetate  of,  186 

analytical  reactions  of,  189, 
420 

antidotes  to,  190 
carbonate  of,  185 
chloride  of,  189 
chromate  of,  189 
derivation  of  word,  29 
gummate  of,  97 
hydrato-carbonate  of,  185 
in  organic  mixtures,  detection 
of,  420 

iodide  of,  188 
nitrate  of,  187 
oleate  of,  188 
oxide  of,  185 
oxyacetate  of,  187 
oxychromate  of,  189 
plaster,  188 

puce-colored  or  peroxide  of, 
187 

quantitative  estimation  of, 
478,  512 
red,  187,  415 
shot,  185 

subacetate  of,  186 
sugar  of,  186 
sulphate  of,  190 
sulphide  of,  189 
native,  185 
test  for,  in  water,  189 
-tree,  190 

volumetric  estimation  of  solu- 
tions of  acetate  of,  478 
white,  185 
Loadstone,  119 
Leaf-green,  416 
Lecanora,  416 
Legumin,  398 
Lemon- chrome,  189 
-juice,  290 
-oil,  406 


Length  unit,  455 
Lentish  tree,  411 
Lepidolite,  201 
Levulose,  363 
Lichen  blue,  416 

Light  carbonate  of  magnesium, 
100 

carburetted  hydrogen,  382 
magnesia,  102 
Lignin,  359 
Lime,  caustic,  91 
chloride  of,  96 
-kiln,  91 
-oil,  406 
quick,  91 
slaked,  91 

superphosphate  of,  292 
-water,  92 
Limestone,  90 

magnesian,  100 
mountain,  100 
Limonis  cortex,  406 

succus,  impurities  in,  544 
Limonite,  129 
Line,  460 
Lini  farina,  402 
semina,  402 

Liniment  of  mercury,  171 
Liniments,  442 
Linimentum  amrnonice,  401 
colds,  401 
Linum,  402 
Linseed,  402 
-cake,  402 
oil,  402 
Liqueurs,  372 
Liqiiidambar  orientale,  413 
Liquid  camphor,  409 
definition  of,  49 

Liquids,  specific  gravity  of,  464 
official,  specific  gravity  of,  464 
Liquor  amrnonice,  77 

amrnonice,  impurities  in,  544 
ammonioe  citratis,  79 
amrnonice  fortior,  77 
amrnonice  fortior,  impurities 
in,  544 

ammonii  acetatis,  78 
antimonii  chloridi,  155 
aniimonii  cJdoridi,  impurities 
in,  544 

antimonii  chloridi,  estimation 
of  antimony  in,  509 
arsenicCtlis,  144 


49* 


582 


INDEX. 


Liquor — 

arsenicaU&,  impurities  in,  544 
arsenici  chloridi,  145 
arsenici  et  hydrargyri  iodidi^ 
143 

arsenici  hydrochloricus,  145 
arsenici  hydrochloricus,  impu- 
rities ill,  544 
atropioi,  350 
atropice  sul})hatis,  350 
bismuthi  et  ammonice  citratisj 
estimation  of  bismuth  in, 
225 

bismuthi  et  ammonice  citratis, 
impurities  in,  544 
calcis,  92 

calcis,  impurities  in,  544 
calcis  chloratce^  96 
calcis  chloratce^  impurities  in, 
545 

calcis  saccharatuSj  92 
calcis  saccharatusj  impurities 
in,  545 
chi  or  i^  240 

chlori,  impurities  in,  545 
fei'ri  citratis^  130 
ferri  perchloridi,  126 
ferri  perchloridi  fortior^  126 
ferri  perchloridi  fortior^  impu- 
rities in,  545 

ferri  perchloridi  fortior,  esti- 
mation of  iron  in,  508 
ferri  pernitratis,  135 
ferri pernitratis,  impurities  in, 
545 

ferri  pernitratis^  estimation  of 
iron  in,  508 
ferri  persulphatis,  137 
ferri  persulphatis,  impurities 
in,  545 

ferri  persulphatis,  estimation 
of  iron  in,  508 
ferri  subsulphatis,  127 
ferri  tersulphatis,  127 
gut ta-per dice,  414 
hydrargyri  nitratis  acidus,  175 
hydrargyri  nitratis  acidus,  im- 
purities in,  545 
hydrargyri  perchloridi,  177 
iodi,  244 

iodinii  compositus,  244 
lithice  effervescens,  201 
hihice  effervescens,  impurities 
in,  545 


Liquor — 

magnesicB  carbonatis,  101 
magnesice  carbonatis,  impuri- 
ties in,  545 
magnesii  citratis,  102 
morphice  acetatis,  341 
morphice  hydrochloratis,  341 
morphice,  sulphatis,  341 
plumbi  subacetatis,  187 
plumbi  subacetatis,  impurities 
in,  545 

jdumbi  subacetatis  dilutus,  187 
potasses,  53,  56 
potasses,  impurities  in,  545 
potasses  effervescens,  59 
potasses  effervescens,  impuri- 
ties in,  545 

potasses,  neutralizing  power 
of,  478 

potasses,  specific  gravity  of, 
466 

potasses,  to  prepare  pure,  56 
potassii  arsenitis,  144 
potassii  citratis,  60 
potassii  permanganatis,  204 
sodes,  68 

sades,  impurities  in,  545 
sodes  chlorates,  72 
sodes  chlorates,  impurities  in, 
545 

sodes  chlorinates,  72 
sodes  effervescens,  71 
sodes  effervescens,  impurities 
in,  545 

sodii  arseniatis,  146 
strychnies,  248 
zinci  chloridi,  112 
Liquorice-sugar,  364 
List  of  apparatus,  ix. 
of  chemicals,  xi. 
of  reagents,  x. 

Litharge,  185 
Lithates,  320 
Lithii  carbonas,  201 

carbonas,  impurities  in,  545 
citras,  200 

citras,  impurities  in,  545 
Lithic  acid,  320 
Lithium,  200 

analytical  reactions  of,  201 
carbonate  of,  201 
citrate  of,  200 
derivation  of  word,  30 
flame,  201 


INDEX. 


683 


Lithium — 

fluoride  of,  201 
silicate  of,  201 
sulphate  of,  201 
urate  of,  201 
Litmus,  83,  416 
paper,  83 
solution  of,  83 
tincture  of,  83 

Litre,  relation  of,  to  pints,  456 
Liver  of  sulphur,  56 
Lixiviation,  73 
Loadstone  or  lodestone,  119 
Lobelia^  352 
Lobelia  vinegar,  265 
Lobelina,  352 
Lobeline,  352 
Logwood,  25,  415 

solution  of  bleached,  by  chlo- 
rine, 25 

Long  pepper,  351 
Looking-glasses,  214 
Lotio  hydrargyri  Jlava,  179 
hydrargyri  179 

Louisa-blue,  416 
Lozenges,  442 
Lucifers,  22 
Lump-sugar,  361 
Lunar  caustic,  193 
Lupuliu,  412 

oleo-resin  of,  41 2 
LupuliiSj  412 
Luteolin,  415 
Luting,  82 

fire-clay,  177 
linseed  meal,  82 
Lycopodium,  403 

Mace,  407 
oil  of,  407 
Mads,  407 
Madder,  415 
Magenta,  417 
Magnesia,  102 

effervescing  citrate  of,  289 
impurities  in,  545 
calcined,  102 
fluid, 101 

hydrous  carbonate  of,  102 
Magnesia  levis,  102 

levis,  impurities  in,  545 
Magnesian  limestone,  100 
Magnesii  carbonas,  100 

carbonas,  impurities  in,  545 


Magnesii — 

carbonas  levis,  100 
carbonas  levis,  impurities  in, 
545 

carbonatis,  liquor,  101 
sulphas,  100 

sulphas,  impurities  in,  545 
Magnesite,  100 
Magnesium,  99 

analytical  reactions  of,  102 
and  ammonium,  arseniate  of, 
103 

and  ammonium,  phosphate 
of,  102 

carbonate  of,  100 
chloride  of,  99 
citrate  of,  290 
derivation  of  word,  29 
detection  of,  in  presence  of 
barium  and  calcium,  106 
euxanthate  of,  415 
for  analytical  purposes,  150 
limestone,  99 
oxide  of,  102 

phosphate  of,  in  bones,  94 
purrate  of,  415 

quantitative  estimation  of, 
505 

separation  from  barium  and 
calcium,  106 
silicate  of,  314 
sulphate  of,  100,  505 
sulphite  of,  273 
Magnetic  iron  ore,  119 
oxide  of  iron,  133 
Magpie  test  for  mercury,  183 
Malachite,  166 
Malate  of  atropine,  350 
nicotine,  352 
Malates,  309 
M^le  fern  oil,  403 
Malic  acid,  309 
Malt,  357 

Manganate  of  potassium,  63,  204 
Manganese,  203 

analytical  reactions  of,  204 
black  oxide  of,  203 
Crum’s  test  for,  207 
derivation  of  word,  30 
quantitative  analysis  of  black 
oxide  of,  506 
sulphate  of,  206 
Manganesii  oxiduin  nigrum,  203 
sulphas,  206 


584 


INDEX 


Manganous  chloride,  204 
hydrate,  206 
sulphide,  206 
Maniitty  364 

impurities  in,  545 
Mannite,  364 

Manufacturing  chemists,  14 

Manures,  analysis  of,  539 

31aranta,  357 

Marble,  90 

Margarine,  402 

Marine  soap,  402 

Marking-ink,  193 

Marl,  116 

Marmalade,  318 

Marmor  album,  90 

Marsh-gas,  382 

Marsh’s  test  of  arsenicum,  149 

Marruhium,  355 

Maryland  senna,  367 

Massicot,  185 

Mastic,  411 

Mastiche,  411 

Mastichic  acid,  411 

Masticin,  411 

Maticce  folia,  355 

Matricaria  chamomilla,  406 

Mauve,  417 

May-apple,  351 

Meadow-sweet,  oil  of,  390 

Measurement  of  temperature,  447 

Measures,  453  et  seq. 

Mechanical  and  chemical  com- 
bination, diflference  between,  27, 
32 

Meconate  of  morphine,  340 
Meconic  acid,  310,  424 
Meconine,  341 
Medicines,  analysis  of,  336 
Meerschaum,  314 
Mel,  363 

impurities  in,  545 
horacis,  297 
depuratum,  364 
sodce  boratis,  297 
Melam,  316 
Melasses,  364 
Melissic  acid,  404 
Melting-points,  Table  of,  451 

of  fats,  etc.,  to  determine,  450 
of  metals,  451 
Melissyl,  palmitate  of,  402 
Melon-essence,  390 
Memoranda,  analytical,  230,327 


Mentha  piperita,  407 
viridis,  407 
Menthene,  407 
Menthol,  407 

Mercuric  ammonium,  chloride  of, 
171 

.chloride,  172,  176 
cyanide,  248 
iodide,  172,  174 
oxide,  178 
oxynitrates,  175 
oxysulphate,  178 
, nitrate,  174 
salts,  171 

salts,  analytical  reactions  of, 
180,  418 
sulphate,  175 
sulphide,  182 
Mercurius  vitce,  156 
Mercurous  ammonium,  chloride 
of,  181 

chloride,  172,  177 
chromate,  292 
iodide,  172 
nitrate,  174 
oxide,  179 
salts,  171 

salts,  analytical  reactions  of. 
183 

sulphate,  175 
sulphide,  182 
Mercury,  170 

amido-chloride  of,  181 
ammoniated,  181 
ammonio-chloride  of,  181 
analytical  reactions  of,  180 
antidotes  to,  184 
basic  sulphate  of,  176 
black  oxide  of,  179 
carbonates  of,  184 
cyanide  of,  248 
chlorides  of,  176 
derivation  of  word,  29 
iodides  of,  172,  181 
galvanic  test  for,  183 
magpie  test  for,  183 
native  sulphide  of,  170 
nitrates  of,  174 
nomenclature  of  salts  of,  171 
of  life,  156 

in  organic  mixtures,  detection 
of,  419 

oxides  of,  178 
oxynitrates  of  175 


INDEX. 


585 


Mercury — 

oxysulpliate  of,  176 
oxysiilpliide  of,  182 
quantitative  estimation  of, 
510 

subchloride  of,  177 
sulphates  of,  175 
sulphide  of,  170,  182 
yellow  oxide  of,  179 
Meta,  meaning  of,  215 
Metaboracic  acid,  297 
Metacinnamein,  413 
Metagummic  acid,  358 
Metallic  elements,  15 
Metalloids,  15 
Metals,  15 

of  minor  pharmaceutical  im- 
portance, 200 

quantitative  estimation  of, 497 
Table  of  the  fusibility  of,  451 
Metamerism,  358 
Metantimonic  acid,  157 
Metaphosphates,  310 
Metaphosphoric  acid,  310 
Metastannates,  215 
Metastannic  acid,  215,  258 
Metastyrol,  413 
Metavanadates,  295 
Methenyl,  386 
IVlpthyl,  381 
conia,  352 
hydride  of,  382 
salicylate,  390 
Methylamine,  339 
Methylated  spirit,  383 

sweet  spirit  of  nitre,  384 
Methylene,  dichloride  of,  386 
Methylic  alcohol,  383 

detected  in  presence  of  ethy- 
lic  alcohol,  383 
Metre,  456 

relation  of,  to  inches, 456, 461 
Metric  system,  454  et  seq, 

of  weights  and  measures,  its 
relation  to  the  English,  456 
et  seq. 

system,  weights  and  measures 
of,  455  et  seq. 

Mezerei  cortex,  411 
Mezereon,  411 
Mica  Panis,  362 
Microcosmic  salt,  332 
Microscopic  examinations  of  uri- 
nary sediments,  433 


Milk,  397 

sugar,  362 
sulphur,  270 
Mimetesite,  295 
Mimotannic  acid,  318 
Mineral  acids,  detection  of  in 
organic  mixtures,  421 
chameleon,  205 
kermes,  158 
kilbride,  129 
purple,  415 
rouge,  415 

Minerals,  general  analysis  of,  329 
et  seq. 

special  analysis  of,  549 
Minim,  460 
Minium,  185 
Mirbane,  essence  of,  391 
Mistura  ferri  aromatica,  138 
ferri  composita,  122 
poiassi  citratis,  290 
Mixture,  different  from  chemical 
combination,  27 
definition  of,  48 
Mixtures,  442 
Mohr’s  burette,  476 
Moist  sugar,  361 
Molasses,  364 
Molecular  volume,  46 
weight,  46,  237,  471 
weights,  definition  of,  50 
Molecule,  definition  of,  48 
Molecules,  36,  48 
Molybdenum,  551 
Molybdic  acid,  427 
Monads,  104 
Monamines,  339 
Monarda,  409 
Monobasic  acids,  237 
Monobasylous  radicals,  237 
Mononitrocellulin,  360 
Monsel’s  solution,  127 
Mordants,  117 
Mori  succus,  415 
Morphia,  or  Morphine,  340 
acetate  of,  340 

analytical  reactions  of,  341, 
424 

hydrochlorate  of,  340 
in  organic  mixtures,  detection 
of,  424 

quantitative  estimation  of, 
533 

Morphice  acetas,  340 


586 


INDEX 


Morphice — 

hydrochloras,  340 
hydroclilorasy  impurities  in, 
546 

murias^  340 
sulphas^  340 
Mosaic  gold,  216 
Moschusy  398 

moschiferus,  298 
Motion  from  heat,  71 
Mountain-blue,  416 
limestone,  99 
Mucic  acid,  365 
Mucilage  of  gum  acacia,  97 
starch,  356 
tragacanth,  97 
Mucilago  acacice^  97 
cunylij  356 
tragacanthcB,  97 
Mucus  in  urine,  420 
Mulberry  calculus,  424 
-essence,  390 
-juice,  415 

Mulder’s  process  for  estimating 
alcohol,  536 

Multiple  proportions,  law  of,  42, 
173,  257 
Murexid,  320 
Musk,  398 
deer,  298 
Mustard,  393 

artificial  oil  of,  393 
essential  oil  of,  393 
fixed  oil  of,  403 
Myrcia  acr/s,  372 
Myristate  of  glyceryl,  402 
Myristic  acid,  404 
Myristica^  407 
Myristicene,  407 
Myristicol,  407 
Myronate  of  potass iumV>'3;  3 
Myroxylon  PereircE^  413 
Toluiferaj  413 
Myrrh,  412 
412 

Myrrhic  acid,  412 

Naphthalic  acid,  299 
Naphthalin,  299 
Narceia,  341 
Narcotine,  341 

Narthex  assafoetida,  412  ' 

Nataloin,  393  ' 

Natrium j 28 


Nectandra  Rodicei,  350 
Nectandrce  cortex,  350 
Nectaudria,  351 
Needle  iron  ore,  129 
Neroli  oil,  406 
Neutral  chromate,  89 
Nickel,  208 

analytical  reactions  of,  209 
arsenio-sulphide  of,  208 
cobalticyanide,  210 
cyanide,  209 
derivation  of  word,  30 
hydrate  of,  209 
separation  of,  from  cobalt,  209 
sulphide  of,  209 

Nicotia,  nicotine,  nicotina,  or  ni- 
cotylia,  352 

Nicotiana  tahacum,  352 
Nihilum  album,  113 
Niobium,  507 

Nitrate  of  ammonium,  257 

argent  - ammon  - ammonium, 
182 

barium,  87 
bismuth,  223 
cadmium,  222 
iron,  134 
lead,  188 
mercury,  174 
potassium,  52,  253 
silver,  192 

silver,  standard  solution  of, 
486 

sodium,  68,  253 

strontium,  202  ^ 

Nitrates,  252 

analytical  reactions  of,  252 
quantitative  estimation  of,5 15  ■ " 
Nitre,  253  < 

cubic,  253 

sweet  spirit  of,  312,  379 
Nitric  acid,  252 

acid,  antidotes  to,  259  ! 

acid  in  organic  mixtures,  de-  j 
tection  of,  421  i 

acid,  volumetric  estimation  ] 
of,  484 

anhydride,  255,  257 
oxide,  preparation  of,  256 
peroxide,  256  i 

Nitrite  of  ethyl,  312 

potassium,  311  ^ 

Nitrites,  311 

analytical  reactions  of,  311 


INDEX 


58T 


Nitrobenzol,  391 

in  oil  of  bitter  almonds,  test 
for,  363 

Mtrocellulin,  360 
Nitrogen,  23 

derivation  of  word,  28 
in  the  atmosphere,  23 
oxides  of,  256 
peroxide  of,  256 
preparation  of,  23 
properties  of,  23 
quantitative  estimation  of,  in 
organic  compounds,  527  et 
seq. 

relative  weight  of,  24 
Nitrohydrochloric  acid,  162,  255 
Nitromuriatic  acid,  255 
Nitrous  acid,  257 
anhydride,  257 
ether,  312 
oxide,  257 

Nomenclature  of  salts  : — 
alkaloids,  339 
anhydrides,  70 
anhydrous  bodies,  70 
-ate,  60 
bi,59 

carbonization,  evaporation, 
ignition,  incineration,  86 
double  salts,  65 
hydrates,  53 
hydrous  bodies,  70 
hyper,  125 
-ic,  -ous,  59,  63,  120 
-ide,  -ite,  63,  120 
iron  salts,  120 
mercury  compounds,  171 
per,  125 

Non-drying  oils,  402 
Non-metallic  elements,  15 
Non-metals,  14 

Nordhausen  sulphuric  acid,  277 
Notation,  37  et  seq. 

Notes,  analytical,  230,  327 
Nutmeg,  expressed  oil  of,  407 
oil  of,  407 

Nutrition,  plastic  elements  of,  398 
Nux  vomica,  347 

Oak-bark,  317 
black,  415 
Oatmeal,  356 
Occlusion,  220,  221 
Ochre,  414 


Octohedral,  148 
(Enanthylic  acid,  404 
Official  liquids,  specific  gravity  of, 
464 

substances,  volumetric  esti- 
mation of,  478,  484,  486, 
489,  492,  494 
Official  formula,  25 
Officinal  formula,  25 
Oil,  almond,  402 
amber,  315 
aniseed,  406 
apple,  389 
bergamot,  406 
bitter  almond,  366 
bitter  almond,  artificial,  391 
buchu,  406 
cacao,  402 
cajuput,  406 
cake,  402 
camphor,  409 
capsicum,  351 
caraway,  407 
cardamoms,  406 
cascarilla,  407 
cassia,  407 
castor,  402,  403 
cedra,  406 
chamomile,  406 
cinnamon,  407 
citron,  406 
citronella,  407 
cloves,  407 
cocoa-nut,  402 
cod-liver,  402 
copaiva,  407 
coriander,  407 
croton,  402,  403 
cubeb,  407 
dill,  406 

elder-fiower,  408 
eucalyptus,  407 
fennel,  407 
garlic,  393 
ginger,  408 
hop,  412 
horsemint,  409 
horseradish,  393,  406 
juniper,  407 
lavender,  407 
lemon,  406 
lime,  406 
linseed,  402 
lycopodium,  403 


688 


INDEX. 


Oil— 

male-fern,  403 
meadow-sweet,  390 
mustard,  artificial,  393 
mustard,  fixed,  403 
mustard,  volatile,  408 
neroli,  406 
nutmeg,  402,  407 
olive,  403 
orange-flower,  406 
orange-rind,  406 
origanum,  407 
orris,  407 
pepper,  353 
peppermint,  407 
pimento,  407 
rose,  407 
rosemary,  408 
rue,  408 
sassafras,  408 
savin,  408 
spearmint,  407 
sperm,  402 
star-anise,  406 
tlieobroma,  402 
thyme,  409 
turpentine,  408 
valerian,  408 
of  vitriol,  276 
wine,  394 
winter-green,  390 
wormseed,  408 

Oils  and  fats,  composition  of,  400 
Oils,  analysis  of,  539 
drying,  402 
essential,  405 
fixed,  402 
non-drying,  403 
volatile,  405 

volatile,  process  for,  405 
Ointments,  442 

Olea  destillata,  impurities  in,  546 
Oleate  of  glyceryl,  400 
ead, 188 
, 400 

. gas,  394 
Oleic  acid,  400 
Oleine,  400 
Oleo-resins,  411 
Oleoresina  capsid^  412 
cuhehcE,  412 
lupulintey  412 
piper  is,  412 
zingiber  is  j 412 


Oleum  amygdalcB  amarm,  366 
arnygdaloe  dulcis,  402 
anethi,  406 
anisi,  406 
anthemidis,  406 
hergamii,  406 
cajuputi,  406 
camphorm,  409 
carui,  407 
caryophylli,  407 
cinnamomi,  407 
copaibcE,  407 
coriandri,  407 
crotonis,  403 
cubebcB,  407 
ethereum,  394 
J'ceniculi,  407 
gaultherim,  390 
juniperi,  407 
lavendulce,  407 
limonis,  406 
Imi,  402 

menthce  piperitce,  407 
menthoe  viridis,  407 
morrhucB,  402 
myristicce,  407 
myristicce  expressum,  402 
olivoe,  403 
origani,  407 
pimentoe,  407 
ricini,  403 
rosce,  407 
rosrnarini,  408 
rutce,  408 
sabince,  408 
sassafras,  408 
sinapis,  408 
succini,  315 

succini  rectijicatum,  315 
terebinthince,  408 
theobromce,  402 
thy  mi,  409 
tiglii,  403 
valeriance,  408 
Olive-oil,  403 
Omentum,  40^ 

Opal,  315 
Opianine,  341 
Opium,  340 

Opium,  detection  of  in  organic 
mixtures,  424 

estimation  of  morphia  in,  532 
impurities  in,  546 
vinegar,  265 


INDEX. 


689 


Orange-chrome,  189 
Orange-flower,  406 
-flower  oil,  406 
-rind  oil,  406 
-wine,  372 
Orchil,  416 
Orcin,  416 
Ordeal-poison,  353 
Orellin,  415 
Organic  analysis,  525 
bases,  338 
chemistry,  338 
compounds,  338 
Orpiment,  415 
Orris,  butter  of,  407 
oil  of,  407 

Ortho,  meaning  of,  311 
Orthophosphates,  312 
Orthophosphoric  acid,  312 
Orthovanadates,  296 
Os,  95 

Os  ustuMf  95 
Osmium,  221,  551 
Otto  of  rose,  407 
Ounce,  453 

-ous,  meaning  of,  63,  120 
Ovi  vitelluSj  396 
Ovu77i,  396 
Ox-bile,  401 
-gall,  401 

Oxalate  of  ammonium,  80 
barium,  282 
calcium,  282 
cerium,  203 
iron,  2^2 
silver,  283 
sodium,  283 
strontium,  202 
Oxalates,  282 

analytical  reactions  of,  282, 
421 

from  phosphates  and  ferric 
oxide,  separation  of,  333 
quantitative  estimation  of,521 
Oxalic  acid,  282 

acid,  antidotes"to,  283 
acid,  in  organic  mixtures,  de- 
tection of,  421 

acid,  standard  solution-  of,  477 
Oxide  of  aluminium,  117 
antimony,  156 
calcium,  91 
chromium,  210 
copper,  167 
50 


Oxide  of — 

iron,  black,  133 
lead,  185 
magnesium,  102 
manganese,  203 
mercury,  178 
silicon,  315 
silver,  193 
tin,  213 
zinc,  113 

Hubbuck’s,  113 
Oxides  of  nitrogen,  257 
Oxidizing  flame,  331 
Oxyacetate  of,  copper,  168 
of  lead,  186 
Oxyacid  salts,  252 
Oxyacids  of  sulphur,  307 
Oxycarbonate  of  bismuth,  224 
Oxychloride  of  antimony,  156 
Oxychromate  of  lead,  189 
Oxygen,  15 

derivation  of  word,  28 
from  ozone  and  antozone,  245 
in  the  air,  15,  24 
its  relation  to  animal  and 
vegetable  life,  18 
preparation  of,  15 
properties  of,  17 
quantitative  estimation  of,  in 
organic  compounds,  525  et 
seq, 

solubility  in  water,  18 
specific  gravity  of,  22 
weight  of  100  cubic  inches, 
470 

Oxygenated  water,  88 
Oxy hydrates  of  iron,  129 
Oxyiodate  of  iron,  264 
Oxymel,  364 

of  squill,  364 

Oxynitrates  of  mercury,  175 
bismuth,  224,  225 
Oxysalts,  254 
Oxysulphate  of  iron,  122 
mercury,  176 

Oxysulphide  of  antimony,  157 
mercury,  182 
Ozone,  211,  245 

Palladium,  221,  551 
Palm-oil,  402 

Palm'ftate  of  cetyl,  402  4 

glyceryl,  402 
melissyl,  402 


590  IxNDEX. 


Palmitic  acid,  404 
Palmitine,  402 
Papaver  rhceas^  415 
somniferurn,  340 
Papaveris  capsulce,  340 
Papaxerine,  341 
Paper,  bibulous,  93 

for  filtering,  93,  497 
Papers,  test-,  83 
Para,  meaning  of,  285 
Paratartaric  acid,  285 
Paraguay  tea,  353 
Pareirce  radix^  351 
Paris  blue,  416 
red,  415 

Particles,  elementary,  B9 
Pearlash,  53 
Pearl-barley,  356 
-white,  224,  417 
Peas,  398 
Pectin,  358 
Pelargonic  acid,  404 
Pellitory  root,  411 
Pelosia,  351 
Pelosine,  351 

Pentacliloride  of  antimony,  156 
Pentatliionic  acid,  307 
Pepper,  black,  353 
cayenne,  351 
cubeb,  353 
long,  353 
white,  353 
oil  of,  353 
resin  of,  411 
Peppermint  oil,  407 
Pepsin,  399 
Per-,  meaning  of,  125 
Perbromates,  242 
Percha  tree,  414 
Perchlorate  of  potassium,  262 
Perchloric  acid,  261 
Perchloride  of  gold,  217 
iron,  125 
platinum,  219 
tin,  214 
Perfumes,  406 
Perhydrate  of  iron,  128 
Permanganate  of  potassium,  64, 
204 

its  use  in  volumetric 
analysis,  488 
Pernitrate  of  iron,  134 
Peroxide  of  barium,  88 
hydrogen,  88 


Peroxide  of — 
iron,  129 

iron,  hydrated,  128 
lead,  187 
nitrogen,  256 

Peroxy hydrate  of  iron,  128 
Persian  berries,  415 
Persulphate  of  iron,  127 
Persulphide  of  hydrogen,  271 
Peru,  balsam  of,  413 
Pervuine,  413 
Petalite,  201 

1 Pettenkofer’s  test  for  presence  of 
bile,  401 

Pewter,  155,  185,  214 
Phaeoretine,  300 
Pharaoh’s  serpent,  316 
Pharmaceutical  chemists,  14 
Pharmaceutical  Society  of  Great 
Britain,  examinations  of,  14 
Pharmacists,  14 
Pharmacy,  14 
Phenic  acid,  391 
alcohol,  391 
Phenol,  391 
Phenyl,  391 
Phenylamine,  393 
Phosphate  of  ammonium,  79 
barium,  295 
calcium,  90,  94,  295 
iron,  123,  295 

magnesium  and  ammonium, 
103 

magnesium  and  ammonium 
from  oxalates  and  ferric 
oxide,  separation  of,  333 
magnesium,  in  bones,  94 
silver,  194 
sodium,  95 

sodium,  how  prepared  from 
phosphate  of  calcium,  95 
Phosphates,  292 

analytical  reactions  of,  294 
quantitative  estimation  of, 
521 

Phosphites,  *^12 
test  for,  313 

Phosphomolybdic  acid,  427 
Phosphoretted  hydrogen,  306 
Phosphoric  acid,  22,  293,  312 
acid,  diluted,  293 
acid,  quantitative  estimation 
of  free,  521 
anhydride,  22,  310 


INDEX. 


591 


Phosphorous  acid,  312 
Phosphorus,  22 

coiribustion  of,  22' 
derivation  of  word,  28 
detection  of,  in  organic  mix- 
tures, 422 
granulated,  293 
properties  of,  22 
red  or  amorphous,  359 
trihydride,  306 
Phthalic  acid,  299 
Phyllocyanin,  416 
Phylloxanthin,  416 
Physostigmatis  faha^  353 
Physostigma,  353 
Physostigmine,  353 
Picric  acid,  392 
Pigments,  414 
Pills,  440 

Pilula  ferri  carhonatis,  122 
fen'i  iodidi,  27 

hydrargyria  171 

hydrargyri  subchloridi  compo- 
sita,  i78 

plumbi  cum  opio^  187 
quinice,  344 

Pilulce  antimonii  compositce,  178 
ferri  compositce,  123 
Pimaric  acid,  410 
Pimento,  407 
oil,  407 

Pimpinella  anisum,  406 
Pine-apple,  essence  of,  390 
Pinic  acid,  410 
Pink  saucers,  416 
the  common,  371 
Pins,  214 
Pint,  460 
Pinus,  408,  412 
Piper  nigrum,  353 
Piperia,  353 
Piperidia,  353 
Piperidine,  353 
Piperine,  353 
Pistachia  terebinthus,  408 
Pitch,  412 

burgundy,  411 
Pix  burgundica,  411 
canadensis,  412 
liquida,  412 

Plants  and  animals,  complemen- 
tary action  on  air,  18 
Plaster  of  ammoniacum  and  mer- 
cury, 171 


Plastej*  of — 

mercury^  171 
Paris;  90,  417 
Plasters,  188,  440 
Plastic  elements  of  nutrition,  398 
Platiiiic  salts,  219 
Platinous  salts,  219 
Platinum,  219 

analytical  reactions  of,  219 
and  ammonium,  chloride  of, 
83,  499 

and  potassium,  chloride  of,  65 
black,  220 

derivation  of  word,  31 
foil,  64,  219 
perchloride  of,  219 
residues,  to  recover,  221 
spongy,  221 
sulphide  of,  220 
Plumbago,  26 
Plumbi  acetas,  1 86 

acetas,  impurities  in,  546 
carbonas,  186 

carbonas,  impurities  in,  546 

emplastrum,  18 

iodidum,  188 

nitras,  187 

oxidum,  185 

oxidum,  impurities  in,  546 
subacetatis,  liquor,  187 
Plummer’s  pills,”  178 
Plumbic  peroxide,  187 

acetate,  sulphate,  etc.,  vide 
salts  of  lead. 

Plumbum , 29 
Pocula  emetica,  155 
Podophylli  radix,  351 
resina,  351 

Poisonous  alkaloids,  423,  425 
Poisons,  antidotes  to,  vide  Anti- 
dotes, detection  of,  in  organic 
mixtures,  418  et  seq» 

Polybasic  acids,  237 
Polybasylous  radicals,  237 
Polychroite,  415 
Poiygala  senega,  371 
Polygalic  acid,  371 
Polymerism,  358 
Polymorphism,  358 
Polymorphous  bodies,  359 
Polysulphide  of  calcium,  270 
Pomegranate  root*  bark,  318 
Porcelain,  314 
Portland  cement,  314 


592 


INDEX 


Potash  alum,  116 

solution  of  caustic,  55 
solution  of  caustic,  to  prepare 
pure,  55 
sulphurated,  56 
vol.  estim.  of  sol.  of,  478 
-water,  56 
Potashes,  52 
Potassa,  56 
Poiassa  caustica,  56 

caustica,  impurities  in,  546 
sulphur  at  a,,  56 

sulphurata,  impurities  in,  546 
Potassce,  vide  Potassii, 

effervescence,  liquor,  59 
liquor,  53,  56 

liquor,  to  prepare  pure,  55 
prussias  Jiava,  248,  302 
Potassic,  hydrate,  etc.,  vide  salts 
of  potassium. 

Potassii  acetas,  57 

acetas,  impurities  in,  546 
bicarbonas,  58 

bicarbonas,  impurities  in,  546 
bichromas,  210 
bitartras,  66,  284 
bromidum,  63 

bromidiun,  impurities  in,  546 
carbonas,  52 
carhonas  pura,  53 
carbonas  impura,  52 
carbonas,  impurities  in,  .546 
chloras,  261 

chloras,  impurities  in,  546 
citras,  60 

citras,  impurities  in,  546 
cyanidum,  248 
et  sodii  tartras,  61,  72 
ferridcyanidum,  impurities  in, 
546 

ferro cyanidum,  248 
hypophosphis,  306 
iodidum,  61 

iodidum,  impurities  in,  546 
nitras,  60,  252 
nitras,  impurities  in,  546 
permanganas,  64,  204 
permanganas,  impurities  in, 
546 

sulphas,  60,  255. 
sulphas,  impurities  in,  546 
sulphis,  270 
sulphuretam,  56 
tartras,  61,  62 


Potassii — 

tartras,  impurities  in,  546 
tartras  acida,  284 
tartras  acida,  impurities  in, 
546 

Potassio-citrate  of  iron,  130 

-tartrate  of  antimony,  157, 
284 

-tartrate  of  iron,  130 
Potassium,  52 
acetate  of,  57 

acid  carbonate  of,  vide  bicar- 
bonate. 

acid  tartrate  of,  65 
analytical  reactions  of,  64 
antimoniate  of,  74 
bicarbonate  of,  58,  478 
bichromate  of,  210 
bitartrate  of,  65,  284 
borotartrate  of,  297 
bromate  of,  63 
bromide  of,  63,  415 
carbonate  of,  53,  478 
chlorate  of,  16,  261 
chloride  of,  65 
chromate  of,  60 
and  platinum,  chloride  of, 
64 

citrate  of,  60 
cobalticyanide  of,  207 
cyanate  of,  300 
cyanide  of,  248 
derivation  of  word,  28 
ferrate  of,  120 
ferriclcyanide,of,  303 
ferrocyanide  of,  248,  301 
-flame-test,  66 
hydrate  of,  54 

hydrate,  to  prepare  pure  so- 
lution, 55 

hypophosphite  of,  306 
iodate  of,  62,  263 
iodide  of,  61 
manganate  of,  64,  186 
myronate  of,  393 
nitrate  of,  52,  60,  252 
oleate  of,  400 
perchlorate  of,  262 
permanganate  of,  64,  204 
preparation  of,  53 
properties  of,  53 
quantitative  estimation  of, 
476,  497 

quantivalence  of,  53 


INDEX. 


593 


Potassium — 

red  chromate  of,  88,  210 
red  prussiate  of,  303 
and  sodium,  tartrate  of,  72 
salts,  analogy  of  to  sodium 
salts,  73 

sodium,  and  ammonium,  sepa- 
ration of,  85 
sources  of,  52 
sulphate  of,  60,  255 
sulphides  of,  56 
sulphite  of,  270 
sulphocyanate  of,  316 
sulphurated,  56 
tartrate  of,  60 

tartrate  of,  acid,  52,  65,  284 
yellow  chromate  of,  60,  210 
yellow  prussiate  of,  247,  301 
Potato-oil,  389 
Poultices,  442 
Pound,  459 
Powder,  bleaching-,  96 
Powders,  442 
soda-,  73 

specific  gravity  of,  467 
Practical  analysis,  84 
Precipitant,*  65 
Precipitate,  65 
Precipitated  chalk,  92 
sulphur,  270 

Precipitates,  soluble,  in  solutions 
of  salts,  231,  250 
to  wash,  92,  93,  490,  508 
to  weigh,  499,  501,503 
Precipitation,  65 

Preparations  of  the  British  Phar- 
macopoeia, chemical,  444 
galenical,  44^ 

Prepared  carbonate  of  calcium,  94 
chalk,  94 
lard,  402 
suet,  402 

Pressure,  correction  of  vol.  of  gas 
for,  469 
gauges,  447 

Principles  of  Chemical  Philoso- 
phy,  32 

Printer’s  ink,  417 
Prismatic  nitre,  252 
Proportions,  atomic,  41,  173 
constant,  41,  49 
multiple,  42,  49 
reciprocal,  41,  50 
Proof  spirit,  373 


Propenyl,  394 
Propionic  acid,  404 
Propyl,  381, 

Propylamine,  339 
Protopine,  341 
Proximate  analysis,  525 
Prune,  363 
Prunum,  363 
Prussian  blue,  303,  416 
Prussiate  of  potash,  red,  303 
of  potash,  yellow,  248,  302 
Prussic  acid,  247 
Pseudomorphia,  341 
Pterocarpi  lignum.,  415 
Pterocarpus  santilinus,  415 
Ptyalin,  438 

Puce-colored  oxide  of  lead,  187 
Puddling,  iron,  119 
Pulvis  algarothi,  156 
angelicus,  156 
antimonialis,  159 
ipecacuanhoi  compositus,  352 
Pulveres  efferoescentes^  73 
aperientes,  287 
Purified  ox-bile,  401 
Purple  of  Cassius,  218 

foxglove,  active  principle  in, 
367 

Purpurine,  432 
Purrate  of  magnesium,  415 
Purree,  415 
Pus,  in  urine,  437 
Putty-powder,  215 
Pyrethrin,  411 
Pyrethri  radix,  411 
Pyrites,  copper,  166 
iron,  119 

Pyroarseniate  of  sodium,  146 
Pyroarseniates,  146 
Pyrogallic  acid,  319 

acid,  use  of  in  gas  analysis, 
319 

Pyroligneous  acid,  265 
Pyrolusite,  20 
Pyrometers,  450 
Pyromorphite,  295 
Pyrophosphates,  296,  311 
Pyrophosphoric  acid,  312,  313 
Pyrovanadates,  295 
Pyroxylic  spirit,  383 
Pyroxylin,  360 
Pyroxylon,  360 

Quadrivalence,  47 


594 


INDEX 


Qualitative  analysis,  84 
Quantitative  analysis,  404  et  seq, 
Quantivalence,  47,  104 

of  atoms,  definition  of,  52 
of  acidulous  radicals,  50 
Quartz,  314 
Quassice  lignum,  343 
Quassin,  343 
Quercitrin,  415 
Quercitron,  415 
Quercus  cortex,  317 
tinctoria,  415 
Queveiine’s  iron,  135 
Quicklime,  91 
Qiiinice  sulphas,  343 

sulphas,  impurities  in,  546 
valerianas,  344 
Quinia,  or  quinine,  343 

analytical  reactions  of,  344 
citrate  of  iron  and,  131 
De  Vry’s  process  for  estimat- 
ing, 529 

disulphate  of,  344 
kinate  of,  343 

quantitative  estimation  of, 
528 

sulphate  of,  344 
Quinia  wine,  344 
Quinicia,  346 
Quinicine,  346 
Quinidia,  346 
Quinidine,  346 
Quinine,  citrate  of,  344 
Quinquivalence,  47 

Radicals,  acidulous,  55,  235 
acidulous,  formulae  of,  55 
alcohol-,  382 
basylous,  104 
definition  of,  54 
Racemic  acid,  285 
Raisins,  363 
Rational  formulae,  373 
Reactions,  analytical,  53 
synthetical,  53 
Reagents,  list  of,  x. 

Real  alcohol,  374 
Realgar,  144 

Reaumur’s  thermometer,  448 
Reciprocal  proportions,  law  of,  42 
Rectification,  109 
Rectified  oil  of  turpentine,  408 
spirit,  lOi),  373 

Red  chromate  of  potassium,  210 


Red— 

coloring-matters,  415 
corpuscles  in  blood,  437 
earth,  415 
enamel  colors,  416 
gravel,  432 
haematite,  119 
iodide  of  mercury,  173 
litmus-paper,  83 
lead,  187,  415 
ochre,  415 

oxide  of  iron,  129,  415 
phosphorus,  259 
-poppy  petals,  415 
precipitate,  178 
prussiate  of  potash,  303 
-rose  petals,  415 
sandal-wood,  415 
Venetian,  129 
Reduced  indigo,  258 
iron,  135 

Reducing  flame,  331 
Reinsch’s  test  for  arsenicum,  148 
Relative  weight  of  hydrogen  and 
oxygen,  22 
Rennet,  397 
Reseda  luteola,  415 
Resin,  410 

of  arnica,  411 
of  cannabis,  411 
of  capsicum,  411 
of  castor,  411 
of  ergot,  411 
of  guaiacum,  369 
of  Indian  hemp,  411 
of  jalap, 369 
of  kamala,  411 
of  kousso,  411 
of  mastic,  411 
of  mezereon,  411 
of  pepper,  353 
of  podophyllum,  351 
of  pyrethrum,  411 
of  rottlera,  411 
of  scammouy,  371 
Resina,  410 
jalapce,  369 
podopliylli,  351 
scammonice,  371 
Resinoid  substances,  410 
Resins,  410 

Respiratory  materials  of  food, 
398 

Retort,  108 


INDEX 


595 


Rhceados  petala^  415 
Rhamni  succusj  367,  416 
Rhamnus  catharticus^  416 
infectorius,  416 
Rhaponticin,  300 
Rbatanj  root,  318 
Rhei  radix,  300 

radix,  impurities  in*  300 
Rlieic  acid,  300 
Rhein,  300 
Rheumin,  300 
Rhodium,  221 

Rhubarb,  oxalate  of  calcium  from, 
435 

Rhubarbic  acid,  300 
Rhubarbarin,  300 
Rhus  cotinus,  414 
Ricinoleate  of  glyceryl,  403 
Ricinoleine,  403 
Roccella,  416 
Rochelle  salt,  72,  286 
Rock-salt,  67 
Roll  sulphur,  269 
Roman  cement,  314 
Rosce  canince  fructus,  363 
centifolice  petala,  407 
gallicce  petala,  415 
Roscoe’s  vanadium,  295 
Rosaniline,  417 
Rose-oil,  407 
-water,  405 
Rosemary-oil,  408 
Rosin,  410 

Rottlera  tinctorial  411 
Rottlerin,  411 
Rouge,  animal,  300,  415 
mineral,  129, 415 
vegetable,  416 
Rubia  tinctorum^  415 
Rubian,  384 
Rubidium,  552 
Ruby,  116 
Rue-oil,  408 
Rumicin,  300 
Rust  of  iron,  120 
Rutate  of  glyceryl,  402 
Ruthenium,  221,  552 
Rutic  acid,  402 
aldehyd,  408 

Sahadilla  or  sabadilline,  354 
Sabince  oleum,  408  • 

Saccharated  carbonate  of  iron, 
122 


Saccharated^ 

carbonate  of  iron,  volumetric 
estimation  of,  492 
Saccharic  acid,  365 
Saccharimetry,  534 
Saccharine  substances,  355,  361 
Saccharometer,  535 
Saccharum  lactis,  362 
purificatuin,  361 
ustuin,  364 
Safety-lamp,  21 
Safflower,  415 
Saffranin,  415 
Saffron,  415 

bastard,  415 
dyer’s,  415 
Safren,  408 
Sago,  356 
Sal-ammoniac,  76 
Salicin,  370 

Salicyl,  hydride  of,  370,  390 

Salicylate  of  methyl,  390 

Salicylous  acid,  390 

Saligenin,  370 

Saliva,  438 

Sal  prunella,  253 

Salt,  common,  67 

definition  of  a,  52 
of  sorrel,  282 
Saltpetre,  253 
Chili,  250 
Salts,  acid,  269 

action  of  the  blowpipe  on,  331 
action  of  heat  on,  330 
action  of  sulphuric  acid  on, 
330 

of  ammonium,  volatility  of,  84 
analogies,  of,  73 
analysis  of  insoluble,  328 
constitution  of,  54,  107,  235, 
253,  267 
formation  of,  58 
nomenclature  of,  59,  63 
of  iron,  nomenclature  of,  120 
physical  properties  of,  329 
substitution  of  for  each  other, 
73 

table  of  the  solubility  or  fn- 
solubility  of,  in  water,  325 
Sal  volatile,  79 
Sambucene,  408 
Sambuci  Jiores,  408 
Sand,  314 
-bath,  24 


596 


INDEX 


Sand — 

-tray,  24,  177 
Sandstone,  314 
Sanguinaria,  353 
vinegar,  2(55 
Santalin,  415 
San  ton  lea,  370 
Santonin,  370 
Santoninum,  370 

impurities  in,  546 
Santoniretin,  370 
Sapan-wood,  415 
Sap-green,  416 
Sapo  durus,  400 

darns,  impurities  in,  546 
mollis,  400 

mollis,  impurities  in,  546 
Saponin,  371 
Sapphire,  116 

Sarcince  ventriculi,  in  urine,  439 
Sarcolactic  acid,  309 
Sarsaparilla,  371 
Sarzee  radix,  371 
Sassafras-oil,  408 
Sassafras  radix,  408 
Sassafrol,  408 

Saturated  solutions,  boiliug-points 
of,  450 

Saturating  power  of  citric  acid, 
290,  549 

power  of  tartaric  acid,  286, 
549 

Saturation,  57 

tables,  286,  290,  549 
Saturn,  186 
Saturnine  colic,  186 
Savin-oil,  408 
Saxon  blue,  416 
Saxony  blue,  416 
Scale  compounds  of  iron,  186 
Scammonice  radix,  371 
resina,  371 

resina,  impurities  in,  547 
Scammonin,  371 
Scammoniol,  371 
Scammonium,  371 
Scammouy,  resin  of,  371 
Scents,  406 
Scheele’s  green,  152 
Schist,  116 

Schonbein’s  test  for  hydrocyanic 
acid,  251 

Schweinfurth  green,  152 
Science  of  chemistry,  14 


Scilla,  364 

Scoparii  cacumina,  353 
Scoparin,  333 
Sea-salt,  67 

Sediments,  urinary,  432 

urinary,  microscopic  exami- 
nations of,  433 
Seidlitz  powder,  287 
Selenium,  552 
Senegee  radix,  371 
Senna  alexandrina,  366 
indica,  367 
Sepia,  417 
Serolin,  396 
SerpentaricB  radix,  355 
Serpent’s  excrement,  309 
Sevum  preeparatum,  402 
Sexivalence,  47 
Shale,  116 
Sherry-wine,  372 
Sienna,  417 

Sifting,  an  aid  to  analysis,  330 
Silica,  314 

Silicate  of  aluminium,  116 
calcium,  90,  314 
magnesium,  314 
Silicates,  314 

quantitative  estimation  of, 
524 

tests  for,  315 
Silicic  acid,  314 
anhydride,  315 
Siliciuretted  hydrogen,  315 
Silico-fluoride  of  barium,  89 
Silicon,  chloride  of,  315 
derivation  of  word,  30 
fluoride  of,  315 
hydride  of,  315 
oxide  of,  315 
Silver,  191 

amraonio-nitrate  of,  153, 182 
analytical  reactions  of,  193 
antidojtes  to  nitrate  of,  195 
arseniate  of,  153 
arsenite  of,  153 
bromide  of,  194 
chloride  of,  192 
chromate  of,  194 
citrate  of,  291 
coinage,  191,  467 
cyanide  of,  194 
by  cupellation,  estimation  of, 
513 

derivation  of  word,  29 


INDEX 


59t 


Silver — 

extraction  of,  191 
German,  109 
iodide  of,  194 
nitrate  of,  191,  192 
oxalate  of,  283 
oxide  of,  193 
phosphate  of,  194 
pure,  192 

quantitative  estimation  of, 
513 

standard  solution  of  nitrate 
of,  486 

sulphide  of,  191 
sulphite  of,  274 
tartrate  of,  288 
tree,  194 

volumetric  estimation  of,  513 
Sinalbin,  393 
Sinapis,  393 

impurities  in,  547 
Siphon,  vide  Syphon. 

Size,  398 
Slaked  lime,  91 
Slate,  116 
Smalt,  207,  416 
Smilacin,  371 

Soap,  ammonium,  calcium,  hard, 
potassium,  sodium,  soft,  400 
Soap-stone,  417 
-wort,  341 
“Soda,”  279,482 
Soda-alum,  116 
-ash,  73,  482 
caustic,  68 
Soda,  68 

caustica,  68 

caustica,  impurities  in,  547 
tartarata,  72 

tartarata,  impurities  in,  547 
Soda-lime,  527 
powders,  73 

solution  of  chlorinated,  72, 
495 

standard  solution  of,  483 
valerianate  of,  321 
volumetric  estimation  of,  478 
water,  71 
Sodse,  vide  Sodii. 

Sodii  acetas,  69 

acetas,  impurities  in,  547 
arsenias,  146 

arsenias,  impurities  in,  547 
hicarbonas,  69,  70 


Sodii — 

bicarhonas,  impurities  in,  547 
boras,  296 
carbonas,  270 

carbonas,  impurities  in,  547 
carbonas,  exsiccata,  70 
chloratce,  liquor,  72,  495 
cliloridum,  67 

citro-tartras  effervescens,  73 
hypophospkis,  306 
hyposulphis,  impurities  in,  547 
liquor,  68 
nitras,  225 

nitras,  impurities  in,  547 
phosphas,  95 

phosphas,  impurities  in,  547 
sulphas,  239 

sulphas,  impurities  in,  547 
sulphis,  273 
valerianas,  321 

valerianas,  impurities  in,  547 
Sodic  carbonate,  etc.,  vida  salts  of 
sodium. 

Sodio-citrate  of  iron,  130 
-tartrate  of  iron,  130 
Sodium,  67 

acetate  of,  69 
acid  carbonate  of,  69,  478 
acid  sulphate  of,  239 
acid  tartrate  of,  66 
analytical  reactions  of,  74 
and  aluminium,  double  chlo- 
ride of,  115 
antimoniate  of,  74 
arseniate  of,  146 
arsenite  of,  144 
bicarbonate  of,  69 
bisulphite  of,  270 
bromate  of,  73 
bromide  of,  73 

carbonate  of,  68,  73,  279,478 
carbonate  of,  manufacture  of, 
73,  279 

chlorate  of,  73 
chloride  of,  67 
citrate  of,  73 
derivation  of  word,  28 
-flame,  74 
hydrate  of,  68 
hypochlorite  of,  72 
hypophosphite  of,  306 
hyposulphite  of,  306 
iodate  of,  73 
iodide  of,  73 


598 


INDEX. 


Sodium— 

maiiganate  of,  73 
nitrate  of,  68,  252 
other  compounds  of,  73 
oxalate  of,  282 
permanganate  of,  73 
phosphate  of,  95 
phosphate  of,  how  prepared 
from  phosphate  of  calcium, 
95 

potassium  and  ammonium, 
separation  of,  85 
p^^roarseniate  of,  146 
quantitative  estimation  of, 
478,  501 

salts,  analogy  of,  to  potassium 
salts,  73 

salts,  sources  of,  67 
sulphate  of,  239 
sulphite  of,  273 
valerianate  of,  321 
Soft  soap,  400 
Soils,  analysis  of,  539 
Solania,  353 
Solanine,  353 
Solarium  dulcamara^  353 
Solder,  185,213 
Solid,  definition  of,  49 
fats,  400 
potash,  56 

Solids  lighter  than  water,  to  take 
the  specific  gravity  of,  468 
to  take  the  specific  gravity 
of,  467  et  seq. 

Solubility  of  carbonic  acid  gas  in 
water,  71 

of  gases  in  liquids,  71 
of  precipitates  in  strong  solu- 
tions of  salts,  231,  250 
or  insolubility  of  salts  in 
water.  Table  of,  325 
Soluble  cream  of  tartar,  297 
glass,  315 

substances,  to  take  the  spe- 
cific gravity  of,  468 
tartar,  297 

Solution  of  acetate  of  ammo- 
nium, 78 

acetate  of  potassium,  57 
acetate  of  sodium,  69 
albumen,  395 
ammonia,  77 

ammonio-nitrate  of  silver, 
153,  182 


Solution  of — 

ammonio-sulphate  of  copper, 
153,  182 

ammonio-sulphate  of  magne- 
sium, 103,  522 
arsenic  in  acid,  145 
arsenic  in  alkali,  144 
boracic  acid,  296 
bromine,  242 

carbonate  of  ammonium,  79 
chloride  of  ammonium,  76 
chloride  of  antimony,  155 
chloride  of  barium,  87 
’chloride  of  calcium,  90 
chloride  of  calcium,  saturat- 
ed, 90 

chloride  of  gold,  217 
chloride  of  tin,  214 
chloride  of  zinc,  112 
chlorinated  lime,  97,  495 
chlorinated  soda,  72,  495 
chlorine,  24,  25 
citrate  of  ammonium,  79 
citrate  of  magnesium,  101 
ferridcyanide  of  potassi  urn, 
304 

ferrocyanide  of  potassium, 
302 

gelatine,  398 

iodate  of  potassium,  62,  263 
iodide  of  potassium,  62 
iodine,  244 
lime,  92 
litmus,  83 

nitrate  of  mercury,  174 
oxalate  of  ammonium,  80 
perchloride  of  iron,  126,  127 
perchloride  of  mercury,  177 
perchloride  of  platinum,  219 
pernitrate  of  iron,  135 
persulphate  of  iron,  127 
phosphate  of  sodium,  96 
phosphoric  acid,  293 
potash,  53,  55 

red  prussiate  of  potash,  304 
soda,  68 
strychnia,  348 
subacetate  of  lead,  186 
sulphate  of  calcium,  97 
sulphate  of  indigo,  258 
sulphate  of  iron,  121 
sulphide  of  ammonium,  80 
sulphydrate  of  ammonium,  80 
tartaric  acid,  285 


INDEX. 


599 


Solution  of — 

yellow  prussiate  of  potash, 
302 

Sonnenschien’s  process  for  poison- 
ous alkaloids,  426 
Soot,  26 

Source  of  heat,  16 
Sovereign,  weight  of  the,  217 
Spar,  fluor-,  304 
heavy,  87 

Sparteiaor  sparteine,  35  3 
Spathic  iron-ore,  119 
Spearmint  oil,  407 
Specific  gravity,  463 

gravity  of  gases,  469 
gravity  of  liquids,  464 
gravity  of  official  liquids,  464 
gravity  of  oxygen,  22 
gravity  of  powders,  467 
gravity  of  solids,  467 
gravity  of  solids  lighter  than 
water,  468 

gravity  of  soluble  substances, 
468 

weight,  463 

Spectrum  analysis,  336 
Specular  iron-ore,  119 
Speculum  metal,  213 
Speiss,  208 
Spermaceti,  402,451 
Spermatozoa,  in  urine,  439 
Sperm-oil,  402 
Spircea  ulmaria,  370 
Spirit  of  French  wine,  376 
methylated,  383 
myrcia,  372 

of  nitrous  ether,  312,  379 
of  nitrous  ether,  adulterated, 
384 

proof,  373 
pyroxylic,  383 
rectified,  373 
of  turpentine,  408 
of  wine,  373 

of  wine,  impurities  in,  487 
wood-,  383 
Spirits,  442 

analysis  of,  536 
Spiritus  cBtheris,  378 
cetheris  nltrosi,  379 
cetheris  nitrosi^  impurities  in, 
547 

ammonice,  79 
ammonice  aromaticuSy  79 


Spiritus  — 

ammonice,  aromaticuSy  impuri- 
ties in,  547 
ammonice  fcetiduSy  79 
anisiy  406 
cajuputi,  405 
cinnamomiy  406 

chloroj'ormi,  impurities  in,  547 

frumentiy  372 

juniperiy  405 

lavandulcCy  405 

menthce  piperitce,  406 

myrciccy  372 

myristiccBy  405 

rectiJicatuSy  448,  473 

rectificatuSy  impurities  in,  547 

rosmariniy  405 

tenutoVy  373 

tenuior,  impurities  in,  547 
vini  gallici,  376 
Spodumene,  201 
Spongy  platinum,  221 
Spruce  fir,  411 
Spurge  laurel,  411 
i'Squill,  364 
Standard  gold,  217 
Standard  solution  of  hyposul- 
phite of  sodium,  493 
solution  of  iodine,  488 
solution  of  nitrate  of  silver, 
486 

solution  of  oxalic  acid,  477 
solution  of  red  chromate  of 
potassium,  491 
solution  of  soda,  483 
solution  of  sulphuric  acid,  482 
Stannate  of  sodium,  215 
Stannates,  215 
Stannic  acid,  215 
anhydride,  215 
chloride,  214 
oxide,  215 
sulphide,  216 

anhydrous,  21  6 
Stannous  chloride,  solid,  214 
hydrate,  216 
oxide,  21 6 
sulphide,  215 
Stannumy  30 
Star-anise  oil,  406 
Starch,  355 
blue,  356 

quantitative  estimation  of, 534 
-sugar,  363  • 


600 


INDEX 


Stas’s  process  for  poisonous  alka- 
loids, 425 
Steam-bath,  500 
Stearic  acid,  400,  404 
Steariiie,  400 
Stearoptens,  405 
Steatite,  417 
Steel,  119 
wine,  133 
Stibium^  29 
Still,  108 

Stoddart’s  test  for  quinine,  345 
Stone-coal,  213 
red,  415 
Storax,  413 
Strarnonii  folia^  350 
sfmina^  350 
Stream-tin,  213 
Strontianite,  202 
Strontium,  202 

analytical  reations  of,  202 
carbonate  of,  202 
derivation  of  word,  30 
flame,  202 
nitrate  of,  202 
sulphate  of,  202 
Structure  of  flame,  21 
Strychnia^  347 
Strychnice  sulphas,  347 
Strychnia  or  strychnine,  347 

or  strychnine,  impurities  in, 
547 

analytical  reactions  of,347,423 
in  organic  mixtures,  detection 
of,  423 

Strychnos  Ignatius,  347 
Strychnos  nux  vomica,  347 
Styracin,  413 
Styrax  benzoin,  413 
prceparalus,  413 
Styrol,  413 
Styrone,  413 

Subacetate  of  copper,  168 
of  lead,  186 

Subcarbonate  of  iron,  122 
Subchloride  of  mercury,  177 
Sublimation,  78,  176 
Sublimed  sulphur,  269 
Subnitrate  of  bismuth,  223 
Substances  readily  deoxidized, 
quantitative  estimation  of, 
493 

readily  oxidized,  quantitative 
estimation  of,  488 


Substitution-products,  386 
Succi,  442 
Succinic  acid,  315 
Succinum,  315 
Succus  limonum,  290 
Sucrose,  361 
Suet,  402 

prepared,  402 
Sugar,  361 

brown,  361 
-candy,  361 
cane-,  361 

detection  of  in  urine,  430 
grape-,  362 
inverted,  361,  362 
lump,  361 
-maple,  361 
milk-,  363 
moist,  362 
of  lead,  186 

quantitative  estimation  of, 534 
tests  for,  361 

Sulphate  of  aluminium,  116 

aluminium  and  ammonium, 
116 

ammonium,  76 
ammonium  and  iron,  117 
barium,  88 
bismuth,  225 
cadmium,  222 
calcium,  90,  97 
chromium,  211 
cinchonia,  346 
cobalt,  207 
copper,  168 

copper,  anhydrous,  168 
cupr-diammon-diammonium, 
182 

indigo,  258 
iron,  121 

iron,  solution  of,  121 
lead,  89 

magnesium,  100,  505 
manganese,  206 
mercury,  175 
potassium,  60,  255 
quinine,  343 
sodium,  239 
strontium,  202 
zinc,  110 
Sulphates,  275 

analytical  reactions  of,  277 
quantitative  estimation  oC 
519 


INDEX. 


601 


Sulpliethylic  acid,  377 
Sulphide  of  ammonium,  80 
antimony,  155,  157 
arsenicum,  151 
arsenicum,  native,  144 
barium,  88 
bismuth,  266 
cadmium,  222 
calcium,  279 
cobalt,  207 
copper,  168 
iron,  121 
lead, 189 
lead,  native,  185 
manganese,  206 
mercury,  182 
mercury,  native,  170 
nickel,  209 
potassium,  56 
silver,  194 
silver,  native,  191 
tin,  215 
zinc,  114 
zinc,  native,  110 
Sulphides,  269 

analytical  reactions  of,  271 
arsenicum,  native,  144 
quantitative  estimation  of, 
517 

Sulphindigotic  acid,  258 
Sulphindylic  acid,  258 
Sulphite  of  barium,  274 
calcium,  274 
magnesium,  273 
potassium,  273 
silver,  274 
zinc,  109 
Sulphites,  272 

analytical  reactions  of,  274 
quantitative  estimation  of, 
519 

Sulphocarbolates,  392 
Sulphocarbolic  acid,  392 
Sulphocyanate  of  allyl,  393 
butyl,  382 
iron,  138 

Sulphocyanates,  316 
Sulphocyanic  acid,  316 
Sulphocyanides,  816 
Sulphocyanogen,  316 
Sulphophenates,  392 
Sulphophenic  acid,  392 
Sulphovinic  acid,  377 
Sulphur,  26 

51 


Sulphur — 

adulteration  of,  271 
allotropy  of,  359 
analytical  reactions  of,  271 
arsenic  in,  152 
bromide  of,  272 
chloride  of,  272 
derivation  of  word,  28 
estimation  of,  517 
flowers  of,  269 
hypochloride  of,  272 
iodide  of,  244 
liver  of,  58 
milk  of,  270 
oxyacids,  307 
plastic,  269 
precipitated,  270 
roll,  269 
sublimed,  269 
Sulphur  loturriy  269 
prcecipitatum,  270 
prcecipitaturrij  impurities  in, 
547 

subliinatum,  269 
sublimatum,  impurities  in,  547 
Sulphurated  antimony,  159 
potash,  56 

Sulpliurets,  vide  Sulphides. 
Sulphuretted  hydrogen,  269 
Sulphuric  acid,  275 

acid,  antidotes  to,  278 
acid,  aromatic,  276 
acid,  dilute,  276 
acid,  fuming,  277 
acid,  Nordhausen,  277 
acid  in  organic  mixtures,  de- 
tection of,  421 
acid,  purification  of,  277 
acid,  standard  solution  of,  482 
acid,  volumetric  estimation  of, 
484 

anhydride,  276 
Sulphuris  iodidum,  214 

iodidum,  impurities  in,  548 
Sulphurous  acid,  26,  272 

acid,  volumetric  estimation 
of,  489 

anhydride,  272 

Sulphydrate  of  ammonium,  solu- 
tion of,  81 

Sulphydric  acid,  81,  269 
Sumatra  camphor,  409 
Sumbul,  412 

1 Superphosphate  of  lime,  292 


602 


INDEX 


Supporters  of  combustion,  21 
Suppositoria  acidi  tanici^  317 
morphice^  341 
pUiinhi  compositaj  186 
Suppositories,  442 
Surface  unit,  455 
Surgery,  14 

Sweet  spirit  of  nitre,  312,  379 

spirit  of  nitre,  adulterated, 
384 

Sylvie  acid,  410 
S.vmbol,  function  of,  37 
Symbols  of  elements,  27,  37 

illustrative  of  chemical  action 
by,  40 

Sympathetic  inks,  208 
Synaptase,  366 
Synthesis,  52 
Syphon,  94 

Syrup  of  iodide  of  iron,  27 
Syrups,  442 

Syrupi,  impurities  in,  548 
Syrupus  aurantii,  406 
aurantii  Jloris,  406 
ferri  iodidi,  27 
ferri  phosphatisj  123 
fuscus,  364 

Tahaci  folia,  352 
Tamarindus,  289 

impurities  in,  543 
Tannic  acid,  317 
Tanning,  318 
Tantalum,  552 
Tapioca,  356 
Taraxaci  radix,  343 
Taraxacin,  243 
Tartar,  meaning  of,  284 
Tartar,  cream  of,  53,  66,  284,  478 
emetic,  157,  284 
emetic,  estimation  of  anti- 
mony in,  509 
Tartarated  antimony,  157 
Tartaric  acid,  284,  315 

saturating  power  of,  286,  549 
solution  of,  385 
Tartarus  boraxatus,  397 
Tartrate  of  ammonium,  84 

antimony  and  potassium, 157, 
284 

calcium,  287 
potassium,  acid,  53,  66 
potassium,  neutral,  66 
potassium  and  sodium,  72 


Tartrate  of — 
silver,  288 
sodium,  66 
Tartrates,  61,  284 

analytical  reactions  of,  287 
volumetric  estimation  of,  485 
Taurine,  401 
Taurocholates,  401 
Tellurium,  552 

Temperature,  correction  of  vol.  of 
gas  for,  469 
measurement  of,  447 
Terehinthina,  408 
canadensis,  408 
Terra  di  sienna,  417 
Terra  jap onica,  318 
Testa  preeparata,  94 
Test-papers,  83 
-tube,  16 
Tetramines,  339 
Tetrathionic  acid,  307 
Tetryl,  381 
Thalleiochin,  344 
Thallium,  552 
Thebaia,  341 
Theia,  353 
Theine,  353 
Thenard’s  blue,  416 
Theobroraa  oil,  402 
Therapeutics,  definition  and  deri- 
vation of,  14 
Theriaca,  364 
Thermometer,  447 
Celsius’s,  448 
Centigrade,  448 
Fahrenheit’s,  448 
Reaumur’s,  448 

Thermometric  scales,  conversion  of 
degrees  of,  449 
Thionic  acids,  307 
Thorinum,  552 
Thorium,  552 
Thorn-apple,  350 
Thus  americanum,  412 
Thyme,  oil  of,  409 
Thymene,  409 
Thymol,  409 
Tiglic  acid,  403 
Tin,  213 

amalgam,  214 
analytical  reactions  of,  215 
antidotes  to,  216 
block,  213 
chloride  of,  214 


INDEX. 


603 


Tin- 

derivation  of  word,  30 
dropped  or  grain,  213 
foil,  214 
granulated,  214 
oxide  of,  215 
perchloride  of,  214 
plate,  214 
prepare-liquor,  215 
-stone,  213 
tacks,  214 
-white  cobalt,  207 
Tinctura  ferri  acetatis,  127 
ferri  perchloridi^  126 
iodi,  244 
iodinii^  244 
iodinii  composita^  244 
quinioe^  344 
Tincturm,  126 
Tinctures,  126,  442 
Tinnevelly  senna,  367 
Titanium,  552 
Tobacco,  353 
Tolu,  balsam  of,  413 
Toluol,  391 
Tons  les  mois,  357 
Toxicology,  418 
Tragacantb,  97 
Tragacantha,  97 
Treacle,  366 
Triads,  165 
Triamines,  339 
Triangle,  wire,  84 
Tribasic  acids,  237 
Trybasylous  radicals,  237 
Triethylamine,  339 
Triethylia,  339 
Trinitro-carbolic  acid,  392 
Trinitrocellulin,  359 
Tripbane,  201 
Trithionic  acid,  307 
Trityl,  381 
Tritylia,  339 
Trivalence,  47 

Trivalent  radicals,  47,  55,  104 
Trochisci  acidi  tannici^  317 
bismuthi,  224 
fei’ri  redacti,  135 
morphicB,  341 

morpliicB  et  ipecacuanhce,  341 
potassce  chloraiis,  262 
sodce  bicarbonatiSf  71 
Tube-funnels,  81 
Tubes  for  collecting  gases,  61 


Tubes — 

glass,  Glass  tubes. 
Tungsten,  552 
Turgite,  129 
Turmeric,  415 
Turmeric  paper,  83,  297 
Turnbull’s  blue,  304,  416 
Turpentine,  408 
American,  408 
Bordeaux,  408 
Canadian,  408 
Chian,  408 
French,  408 
rectified  oil  of,  408 
spirit  of,  408 
Venice,  408 
Turpetb  mineral,  176 
Turps,  408 
Type-metal,  155,  185 

Ulmi  cortex^  318 
Uhnus  fulva,  318 
Ultimate  analysis,  525 
Ultramarine  blue,  416 
green,  416 
Umber,  417 

Unguentum  aconitice,  349 
antimonii  tartarati^  157 
atropice^  350 
cadmii  iodidi^  221 
cerusscBf  186 
hydrargyria  171 
hydrargyri  ammoniati,  182 
hydrargyri  iodidi  rubric  174 
hydrargyri  nitratis,  175 
hydrargyri  oxidi  rubri,  179 
hydrargyri  subchloridi,  178 
iodi,  244 

iodinii  compositum^  244 
pJumbi  acefatis,  187 
plumbi  carbonatis,  186 
plumbi  iodidi,  188 
plumbi  subacetatis  compositum^ 

187 

sulphuris  iodidi,  244 
veratrice,  354 
zinci,  112 

Units  of  capacity,  455 
surface,  455 
weight,  455 
Univalence,  47 

Univalent  radicals,  47,  55,  104 
Uranium,  552 
Urate  of  lithium,  201 


604 


INDEX. 


Urates,  320 
UrceoJa  elastica^  493 
Urea,  301,  430 

artificial,  301,431 
Uric  acid,  320,  434 
Urinary  calculi,  439 

calculi,  examination  of,  439 
deposits  or  sediments,  plates 
of,  vide  434  et  seq, 
sediments,  432 
sediments,  microscopical  ex- 
amination of,  433 
Urine,  429 

diabetic,  362,  430,  534 
morbid,  examination  of,  429 
Urinometer,  466 
Uvce,  363 

ursi  folia,  310 

Valerian  oil,  408 
Valeriance  radix,  408 
Valerianate  of  amyl,  389 
of  quinia,  344 
sodium,  321 
zinc,  113,  321 
Valerianates,  320 
Valerianic  acid,  320,  404 
Valerol,  408 
Vanadates,  296 
Vanadinite,  296 
Vanadium,  296,  552 

relationship  to  nitrogen,  phos- 
phorus, and  arsenicum,  296 
Vanilla,  413 

Vapor  acidi  hydrocyanici,  249 
chlori,  25 
conice,  352 
iodi,  243 

Vapor-density,  470 
Variolaria,  416 
Vegetable  albumen,  298 

and  animal  life,  relation  of,  7 

casein,  356,  398 

crocus,  415 

fibrin,  356,  398 

gelatine,  358 

green,  416 

jelly,  358 

oil,  400 

rouge,  416 

substances,  338  et  seq, 
Venetian  red,  129 
Venice  turpentine,  408 
} 'eratri  viridis  radix,  354 


Veratria,  354 

impurities  in,  548 
Veratria  or  Veratrine,  354 
Veratrum  album,  354 
Verdigris,  168 
Vermilion,  182 
Vinegar,  265 

of  cantharides,  265 
squill,  265 

Vinuin  antimonale,  157 
aurantii,  372 
ferri,  133 
ferri  citratU,  133 
poi'tense,  372 
quinice,  344 
xericum,  372 
Vitriol,  blue,  121 
green,  121 
oil  of,  276 
white,  121 

Volatile  oils,  vide  Oils. 

Volatility  of  salts  of  ammonium, 
84 

Volatilization,  84 
Volcanic  ammonia,  76 
Volume,  combination  by,  44 
of  gas,  corrections  of,  469 
molecular,  46 
Volumetric  analysis,  475 

estimation  of  acetate  of  lead, 
480 

estimation  of  acetic  acid,  484 
estimation  of  acids,  483 
estimation  of  alkalies,  476 
estimation  of  alkaline  carbo- 
nates, 481 

estimation  of  ammonia  solu- 
tions, 478 

estimation  of  arseniate  of 
iron,  492 

estimation  of  arseniate  of  so- 
dium, 487 

estimation  of  arsenic  and 
arsenical  solutions,  489 
estimation  of  borax,  480 
estimation  of  bromides,  487 
estimation  of  bromide  of  po- 
tassium, 487 

estimation  of  chlorides,  515 


estimation 
lime,  495 

of 

chlorinated 

estimation 
soda,  494 

of 

chlorinated 

estimation  of  chlorine,  495 


INDEX. 


605 


Volumetric — 

estimation  of  citrate  of  potas- 
sium, 481 

estimation  of  citrates,  481 
estimation  of  cyanides,  487 
estimation  of  hydrochloric 
acid,  484 

estimation  of  hydrocyanic 
acid,  487 

estimation  of  hyposulphite  of 
sodium,  489 

estimation  of  iodides,  487 
estimation  of  magnetic  oxide 
of  iron,  492 

estimation  of  nitric  acid,  484 
estimation  of  official  com- 
pounds, 478,  484,  486,  489, 
492,  494 

estimation  of  phosphate  of 
iron,  492 

estimation  of  potash,  478 
estimation  of  saccharated  car- 
bonate of  iron,  492 
estimation  of  soda,  478 
estimation  of  sugar,  534 
estimation  of  sulphides,  517 
estimation  of  sulphites,  519 
estimation  of  sulphuric  acid, 
484 

estimation  of  sulphurous  acid, 
489 

estimation  of  tartrates,  481 
solutions,  477,  482,  4b3,  486, 
488,  491,493 

Vulcanite,  414 

Vulcanized  India-rubber,  414 

Washing-bottles,  93,  498 
precipitates,  93,  499 

Warmth  of  animals,  how  kept  up, 
18 

Water,  108 

aerated,  71 
-bath,  500 
boiling-point  of,  450 
chalybeate,  119 
composition  of,  20 
crystallization,  70 

quantitative  estimation 
of,  524 

cubic  inches  of,  in  a gallon, 
469 

distilled,  109 
evaporation  of,  58 


Water — 

formation  of,  expressed  by 
symbols,  39 
hardness  of,  281 
lime-,  92 

of  crystallization,  70,  71 
-oven,  498 
oxygenated,  88 
purification  of,  108,  281 
softness  of,  281 
weight  of  1 cubic  inch  of,  470 
weight  of  minim,  drachm, 
ounce,  pint,  and  gallon,  460 
Wax,  402 

Weighing-tubes,  498 
Weight,  452 

estimation  of,  452 
molecular,  46 
of  air,  470 
of  hydrogen,  470 
of  water,  470 
specific,  463 
Weights,  atomic,  43 

and  measures  of  the  British 
Pharmacopoeia  of  1867,  459 
and  measures  of  the  metric 
decimal  system,  454  et  seq, 
balance,  453 

relation  of  metrical  to  the 
weights  of  the  U.  S.  Phar- 
macopoeia, 458,  459 
relative,  44 
Weld,  415 
Welding,  221 
Wheaten  fiour,  355 
Whey,  362,  397 
Whiskey,  372 
White  arsenic,  144 
indigo,  258 
lead,  186 
pepper,  353 
pigments,  417 
precipitate,  fusible,  181 
infusible,  182 
resin,  410 
vitriol,  121 
wax,  402,  457 
Whiting,  94 
Willow  bark,  370 
Wine,  372,  493 

antimonial,  157 
iron,  133 
orange,  372 
quinine,  341 


606 


INDEX. 


Wine — 

sherry,  372 
steel,  133 

Winter-green,  oil  of,  390 
Wire-gauze  tray,  24 
triangle,  84 
Witherite,  87 
Wood-charcoal,  95 
creasote,  391 
naphtha,  383 
oil,  412 
spirit,  383 
tar,  412 

Woody  nightshade,  353 
Wormseed,  408 
Wrought  iron,  120 

Xanthin,  441 
Xylol,  391 

Yard,  460 
Yeast,  372 
Yelk  of  egg,  396 

Yellow  chromate  of  potassium, 
210 

coloring-matters,  414 
ochre,  414 

oxide  of  mercury,  179 
prussiate  of  potassium,  248, 
302 

sienna,  414 
wax,  402,  457 
wood,  414 
Yolk  of  egg,  396 
Yttrium,  552 

Zaflfre,  207 
Zinc,  109 

acetate  of,  112 
analytical  reactions  of,  114 


Zinc — 

antidotes  to,  115 
carbonate  of,  109,  112 
chloride  of.  111 
derivation  of  word,  29 
detection  of  in  presence  of 
aluminium  and  iron,  139 
-ethyl,  380 
ferrocyanide  of,  114 
granulated,  19 
hydrate  of,  114 
in  organic  mixtures,  detection 
of,  421 
oxide  of,  113 
oxide  of,  Hubbuck’s,  113 
quantitative  estimation  of,  506 
sulphate  of,  110 
sulphide  of,  114 
sulphide  of,  native,  109 
sulphite  of,  114 
valerianate  of,  113 
wliite,  113 
Zinci  acetaSy  113 

acetas,  impurities  in,  548 
carbonas,  109,  112 
carbonasy  impurities  in,  548 
chloridiy  liquor y 112 
chloridurriy  111 

chloriduMy  impurities  in,  548 
oxiduniy  113 

oxiduMy  impurities  in,  548 

sulphasy  110 

sulphasy  impurities  in,  548 
unguentuMy  112 
valerianasy  113,  321 
valerianasy  impurities  in,  548 
Zincuiriy  110 

granulaturRy  19 
Zingiber y 408  ^ 

Zirconium,  552 


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